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NT1 is a rare, chronic and disabling neurological disease causing excessive daytime sleepiness and cataplexy. NT1 is characterized pathologically by an almost complete loss of neurons producing the hypocretin (HCRT)/orexin neuropeptides in the lateral hypothalamus. While the exact etiology of NT1 is still unknown, numerous studies have provided compelling evidence supporting its autoimmune origin. The prevailing hypothetical view on the pathogenesis of NT1 involves an immune-mediated loss of HCRT neurons that can be triggered by Pandemrix® vaccination and/or by infection in genetically susceptible patients, specifically carriers of the HLA-DQB1*06:02 MHC class II allele. The molecular mechanisms by which infection/vaccination can induce autoimmunity in the case of NT1 remain to be elucidated. In this review, evidence regarding the involvement of vaccination and infection and the potential mechanisms by which it could be linked to the pathogenesis of NT1 will be discussed in light of the existing findings in other autoimmune diseases., Competing Interests: Declaration of competing interest None., (Copyright © 2024. Published by Elsevier B.V.)

Study Objectives: Modafinil is a common treatment for excessive daytime sleepiness (EDS) in narcolepsy. The long-term use of modafinil can lead to tolerance with the loss of efficacy and the continuous increase of its dose. Pharmacological strategies to deal with the tolerance to modafinil are lacking. We investigated the efficacy and safety of pitolisant-supported bridging during drug holidays in patients with tolerance to modafinil., Methods: Narcolepsy patients on monotherapy with modafinil who developed symptoms of tolerance were eligible. The following alternating therapy regimen was established: Monday to Friday patients continued on modafinil whereas Saturday and Sunday they switched to pitolisant to "bridge" the EDS symptoms. Patients were assessed at baseline and after three months with the Epworth Sleepiness Scale (ESS) and the Ullanlinna Narcolepsy Scale (UNS). Health-related quality of life (HrQol) was evaluated by EuroQol5D. Adverse events were documented in the patients' diaries., Results: 41 patients aged 30.9 ± 5.6 years were included. After three months of the alternating therapy regimen, the symptoms of tolerance decreased and the modafinil dose could be reduced by 41% (p < 0.01) resulting in better safety. The EDS improved on ESS (baseline: 18.2 ± 4.2, follow-up: 12.6 ± 4.0, p < 0.0001) and UNS (baseline: 25.8 ± 7.9, follow-up: 18.9 ± 5.9, p < 0.0001). The HrQol increased significantly., Conclusion: Patients with tolerance to modafinil could benefit from pitolisant-supported bridging during drug holidays. This alternating pharmacological strategy proved to be safe and helped to reduce EDS and to decrease the modafinil dose. Further randomized controlled studies are required to evaluate the different strategies to deal with the tolerance to modafinil., Clinical Trial Registration Number: Clinical Trials.gov Identifier NCT05321355., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: YW reports honoraria for educational presentations and consultations from Angelini Pharma, Arvelle Therapeutics, Bayer AG, BIAL, Bioprojet, Bristol-Myers Squibb, JAZZ pharmaceuticals, Eisai, LivaNova, Novartis, Precisis and UCB Pharma. SG received compensation for professional services from Abbott, Abbvie, Bial, Medtronic, UCB and Zambon; research grants from Abbott, Boston Scientific, MagVenture, German Research Council and German Ministry of Education and Health. UK received honoraria for consulting from AOP Health, Bioprojet Pharma, Jazz Pharmaceuticals and Takeda Pharma. CL received honoraria for consulting and educational presentations from Bioprojet, UCB and Jazz Pharmaceuticals. Financial disclosure of VF, DA and EE: none. Non-financial disclosure of YW, SG, UK, CL, VF, DA and EE: none., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Narcolepsy type 1 (NT1) is caused by a loss of hypocretin/orexin transmission. Risk factors include pandemic 2009 H1N1 influenza A infection and immunization with Pandemrix®. Here, we dissect disease mechanisms and interactions with environmental triggers in a multi-ethnic sample of 6,073 cases and 84,856 controls. We fine-mapped GWAS signals within HLA (DQ0602, DQB1*03:01 and DPB1*04:02) and discovered seven novel associations (CD207, NAB1, IKZF4-ERBB3, CTSC, DENND1B, SIRPG, PRF1). Significant signals at TRA and DQB1*06:02 loci were found in 245 vaccination-related cases, who also shared polygenic risk. T cell receptor associations in NT1 modulated TRAJ*24, TRAJ*28 and TRBV*4-2 chain-usage. Partitioned heritability and immune cell enrichment analyses found genetic signals to be driven by dendritic and helper T cells. Lastly comorbidity analysis using data from FinnGen, suggests shared effects between NT1 and other autoimmune diseases. NT1 genetic variants shape autoimmunity and response to environmental triggers, including influenza A infection and immunization with Pandemrix®., (© 2023. The Author(s).)

Background: First symptoms of narcolepsy mostly present during childhood. Pharmacological management options in children are limited, also due to approval status. Pitolisant is an inverse histamine 3 receptor agonist and has been approved for the treatment of adult narcolepsy with or without cataplexy by EMA and FDA. Clinical experience indicates for a beneficial use also in children and adolescents. Our goal was to evaluate the effects and tolerability of pitolisant in narcolepsy children/adolescents in a real-world setting., Methods: This multicentre retrospective observational study included 55 patients with narcolepsy from three international narcolepsy centers (Germany, France and Italy) who were treated with pitolisant. Patients were eligible if they were at least 6 years old and diagnosed with narcolepsy type 1 or 2. Demographic and clinical characteristics, questionnaires, sleep medicine and laboratory data were collected., Results: 55 children/adolescents (25 girls, 45.45%, 30 boys, 54.55%) aged 6-18 years, with narcolepsy (type 1 = 92.7%, type 2 = 7.3%), were treated with pitolisant. The mean pitolisant dose was 34.1 mg/d. Treatment was effective for excessive daytime sleepiness (EDS) and cataplexy: the pediatric Epworth Sleepiness Scale (ESS) score decreased from 19 to 13.5 (p < 0.001) and the weekly cataplexy frequency improved from 7.9 at baseline to 5.2 (p < 0.001). Treatment with pitolisant was well tolerated. Side effects were mild and mostly short-term. Insomnia was reported most frequently (5.5%)., Conclusion: First real-world results suggest that pitolisant treatment is effective in improving EDS and cataplexy in children with narcolepsy, and also is well tolerated., Competing Interests: Declaration of competing interest UK reports receiving research grants from Bioprojet Pharma, Jazz Pharmaceuticals, and serving as a consultant or advisory board member for AOP Orphan Pharmaceuticals, Bioprojet Pharma, Harmony Biosciences, Jazz Pharmaceuticals, Takeda Pharmaceutical Co., Ltd., and UCB Pharma. ML reports serving as a consultant and participating in advisory boards for NLS Pharma, Jazz Pharmaceuticals, UCB Pharma, and Bioprojet; and receiving grant support from Shire. APdL reports no conflict of interest. LL reports no conflict of interest. GP reports participating in advisory boards for UCB, Jazz Pharmaceuticals, and Bioprojet. FP received fee from Jazz for symposia, support for attending congress from Bioprojet, and participated to advisory board for Takeda. RR reports no conflict of interest. AT reports no conflict of interest. SV reports no conflict of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Pitolisant is a histamine 3-receptor antagonist/inverse agonist effective and safe for the treatment of excessive daytime sleepiness and cataplexy in narcolepsy. We report a 19-year-old woman affected by narcolepsy type 1 who presented panic attacks and dissociative symptoms induced by pitolisant. The patient medical history was unremarkable except that for familiarity for anxiety disorder and chronic insomnia. Moreover, a detailed psychometric evaluation revealed a profile of low resilience, a severe grade of depression, an anxiety trait and a propension to dissociative symptoms. Our report suggests that caution should be used in patients with predisposing factors to psychiatric disorders, especially during the first period of treatment with pitolisant. In consideration of the high prevalence of psychiatric comorbidities in narcolepsy, it seems worth to carefully investigate psychiatric background of narcoleptic patients., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Objectives: Treatment for narcolepsy with sodium oxybate (SXB) has required twice-nightly dosing, at bedtime and 2.5-4 h later. This study evaluated the pharmacokinetics of FT218, an investigational, extended-release, once-nightly formulation of SXB (ON-SXB), vs twice-nightly SXB., Methods: In this phase 1, open-label study, healthy volunteers were randomized (1:1) to ON-SXB 6 g or twice-nightly SXB (two 3-g doses administered 4 h apart); minimum 3-day washout before crossover. Doses were administered 2 h post-evening meal. Blood samples for pharmacokinetic assessments were collected predose and up to 14 h after the first dose during each treatment period., Results: Twenty-eight participants were enrolled (mean age, 39.6 years; 54% women; 93% white). Mean ± SEM area under the concentration-time curve for ON-SXB was 282.7 ± 30.2  μg·h/mL vs 273.3 ± 27.8 μg·h/mL for twice-nightly SXB. Geometric mean ratio (GMR; 90% CI) was 102.9 (98.0-108.0). Maximum γ-hydroxybutyrate (GHB) plasma concentration (C max ) was 65.8 ± 4.0 μg/mL for ON-SXB vs 77.1 ± 4.9 μg/mL for twice-nightly SXB (GMR [90% CI], 88.3 [80.5-97.0]). The GMR (90% CI) for GHB plasma concentrations 8 h post dose (C 8h ) for ON-SXB vs twice-nightly SXB was 61.7 (45.8-83.0). The most frequently reported adverse events were the same for ON-SXB and twice-nightly SXB (nausea, dizziness, somnolence, vomiting)., Conclusions: GHB exposure and C max with one 6-g dose of ON-SXB were bioequivalent to those with two 3-g doses of twice-nightly SXB, whereas C 8h was lower with ON-SXB. If approved, ON-SXB will provide a single bedtime oxybate option, with clinically relevant pharmacologic exposure during the entire sleep period., Competing Interests: Declaration of competing interest RB is a shareholder in WaterMark Medical and Healthy Humming, LLC; serves on the board of directors for the National Sleep Foundation and WaterMark Medical; is a consultant for Jazz Pharmaceuticals, Takeda Pharmaceutical Co., Avadel Pharmaceuticals, and Oventus; has received industry-funded research grants from Avadel Pharmaceuticals, BrescoTec, Bayer, Idorsia, Suven Life Sciences Ltd, Jazz Pharmaceuticals, Balance, Vanda, Merck & Co., Eisai, Philips, FRESCA Medical, Takeda Pharmaceutical Co., LivaNova, Roche, and Sommetrics; and has served on speakers bureaus for Jazz Pharmaceuticals, Eisai, and Harmony Biosciences. MJT has served as a consultant or on advisory boards for Axsome Therapeutics, Balance Therapeutics, Eisai, Avadel Pharmaceuticals, Harmony Biosciences, Jazz Pharmaceuticals, NLS Pharmaceuticals, Suven Life Sciences Ltd, and Takeda Pharmaceutical Co. JWW receives consultation fees from Avadel Pharmaceuticals, Emalex Biosciences, Noctrix Health, Disc Medicine, and Idorsia Pharmaceuticals; and research support from Merck Pharmaceuticals, American Regent, National Institute on Drug Abuse (NIDA), the RLS Foundation, and the Baszucki Brain Research Fund. JD and DS were employees of Avadel Pharmaceuticals at the time of the study. JG is an employee of Avadel Pharmaceuticals., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Narcolepsy is a rare condition in Israel. Currently, the incidence of narcolepsy following SARS-CoV-2 vaccination in Israel is unknown. We are reporting a case report of a 51-year-old woman of Ashkenazi Jewish descent who was evaluated for complaints of excessive daytime sleepiness and relative functional decline that immediately followed receipt of the Pfizer/BioNTech SARS-CoV-2 vaccination. Evaluation of patient-reported data with polysomnography and multiple sleep latency test was consistent with narcolepsy with cataplexy, meeting the criteria for a diagnosis of type 1 narcolepsy. Further investigation included human leukocyte antigen testing. Prior studies have demonstrated genetic, immunological, and environmental factors associated with narcolepsy following other vaccinations. This case is a valuable contribution to the literature as there are no prior reports of type 1 narcolepsy following SARS-CoV-2 vaccination in the State of Israel., Citation: Mahamid A, Bornstein RJ, Amir H. Pfizer/BioNTech SARS-CoV-2 vaccine as a potential trigger for the development of narcolepsy: a case report. J Clin Sleep Med . 2022;18(10):2503-2506., (© 2022 American Academy of Sleep Medicine.)

Narcolepsy with cataplexy or narcolepsy type 1 is a disabling chronic sleep disorder resulting from the destruction of orexinergic neurons in the hypothalamus. The tight association of narcolepsy with HLA-DQB1*06:02 strongly suggest an autoimmune origin to this disease. Furthermore, converging epidemiological studies have identified an increased incidence for narcolepsy in Europe following Pandemrix® vaccination against the 2009-2010 pandemic 'influenza' virus strain. The potential immunological link between the Pandemrix® vaccination and narcolepsy remains, however, unknown. Deciphering these mechanisms may reveal pathways potentially at play in most cases of narcolepsy. Here, we developed a mouse model allowing to track and study the T-cell response against 'influenza' virus haemagglutinin, which was selectively expressed in the orexinergic neurons as a new self-antigen. Pandemrix® vaccination in this mouse model resulted in hypothalamic inflammation and selective destruction of orexin-producing neurons. Further investigations on the relative contribution of T-cell subsets in this process revealed that haemagglutinin-specific CD4 T cells were necessary for the development of hypothalamic inflammation, but insufficient for killing orexinergic neurons. Conversely, haemagglutinin-specific CD8 T cells could not initiate inflammation but were the effectors of the destruction of orexinergic neurons. Additional studies revealed pathways potentially involved in the disease process. Notably, the interferon-γ pathway was proven essential, as interferon-γ-deficient CD8 T cells were unable to elicit the loss of orexinergic neurons. Our work demonstrates that an immunopathological process mimicking narcolepsy can be elicited by immune cross-reactivity between a vaccine antigen and a neuronal self-antigen. This process relies on a synergy between autoreactive CD4 and CD8 T cells for disease development. This work furthers our understanding of the mechanisms and pathways potentially involved in the development of a neurological side effect due to a vaccine and, likely, to narcolepsy in general., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Lower-sodium oxybate (LXB) is an oxybate medication with the same active moiety as sodium oxybate (SXB) and a unique composition of cations, resulting in 92% less sodium. LXB was shown to improve cataplexy and excessive daytime sleepiness in people with narcolepsy in a placebo-controlled, double-blind, randomized withdrawal study (NCT03030599). Additional analyses of data from this study were conducted to explore the effects of LXB on cataplexy, including the clinical course and feasibility of transition from other anticataplectics to LXB monotherapy., Objective: The aim of these analyses was to evaluate cataplexy frequency during initiation/optimization of LXB and taper/discontinuation of prior antidepressant/anticataplectic medications., Methods: Eligible participants (adults aged 18-70 years with narcolepsy with cataplexy) entered the study taking SXB only (group A), SXB + other anticataplectics (group B), or anticataplectic medication other than SXB (group C), or were cataplexy-treatment naive (group D). LXB was initiated/optimized during a 12-week, open-label, optimized treatment and titration period (OLOTTP). Other anticataplectics were tapered/discontinued during weeks 3-10 of OLOTTP. A 2-week stable-dose period (SDP; during which participants took a stable dose of open-label LXB) and 2-week double-blind randomized withdrawal period (during which participants were randomized to continue LXB treatment or switch to placebo) followed OLOTTP. Treatment-emergent adverse events (TEAEs) were recorded throughout the duration of the study., Results: At the beginning of OLOTTP, median weekly cataplexy attacks were lower in participants taking SXB at study entry (SXB only [2.00]; SXB + other anticataplectics [0.58]) versus participants who were taking other anticataplectics (3.50) or were anticataplectic naive (5.83). Median weekly cataplexy attacks decreased during weeks 1-2 of OLOTTP in all groups. Increased cataplexy frequency was observed in participants tapering/discontinuing other anticataplectics during weeks 3-10 and was more prominent in participants taking other anticataplectics alone compared with those taking SXB plus other anticataplectics. Cataplexy frequency decreased throughout initiation/optimization in anticataplectic-naive participants. Median number of cataplexy-free days/week at the end of SDP (study week 14) was similar in all groups (6.0, 6.1, 6.0, and 6.2 in groups A, B, C, and D, respectively). During OLOTTP and SDP, TEAEs of worsening cataplexy were reported in 0%, 47.8%, 16.7%, and 2.2% of participants in groups A, B, C, and D, respectively; most TEAEs of worsening cataplexy were reported during tapering/discontinuation of other anticataplectics., Conclusions: LXB monotherapy was effective in reducing cataplexy and increasing cataplexy-free days. These results illustrate the feasibility of switching from SXB to LXB while tapering/discontinuing other anticataplectics., Trial Registration: A Study of the Efficacy and Safety of JZP-258 in Subjects With Narcolepsy With Cataplexy; https://clinicaltrials.gov/ct2/show/NCT03030599 ; clinicaltrials.gov identifier: NCT03030599., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Aim: We assessed psychosocial burdens in children who developed narcolepsy after receiving the Pandemrix H1N1 vaccine during the 2009-2010 pandemic. Parental quality of life was also assessed., Methods: This multicentre study covered four of the five Finnish University Hospital Districts, which dealt with about 90% of the paediatric narcolepsy cases after the Pandemrix vaccination. The medical records of children diagnosed from 2010 to 2014 were reviewed. The questionnaires included the Youth Self-Report (YSR), Children's Depression Inventory (CDI), the Child Behaviour Checklist (CBCL) and questions on parental resources, stress and quality of life., Results: We obtained the medical records of 94 children who were aged 5-17 years at the time of their narcolepsy diagnosis and questionnaire data for 73 of those children. Most children had strong narcolepsy symptoms, and 25% had CDI scores that suggested depression. In addition, 41% had total CBCL problem scores above the clinically significant limit and 48% were anxious, withdrawn and had somatic complaints. Sleep latency was weakly associated with the CBCL total problem score. Half of the children needed psychiatric interventions and parental stress was common., Conclusion: Depression and behavioural problems were common in children with narcolepsy after the Pandemrix vaccination and their parents frequently reported feeling stressed., (© 2021 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.)

The article traces the emergence of a new type of vaccine injury-vaccine-associated narcolepsy-following immunization with Pandemrix vaccine during the 2009 H1N1 pandemic in Europe. The article highlights the processual nature of vaccine injury: it shows how vaccine-associated narcolepsy emerges gradually as a recognized object through epidemiological and immunological studies as well as patient organizations' public discourses. The article argues that despite public recognition of injury, vaccine-associated narcolepsy remains an incongruous object characterized by underlying tensions. These tensions take shape in relation to the history of vaccine injury debates, on the one hand, and the connection between vaccine-associated narcolepsy and non-vaccine-related narcolepsy, on the other. The article shows how these underlying tensions enable a range of mutually incompatible framings and mobilizations through which risk, harm, responsibility, and justice are claimed and negotiated.

Narcolepsy type 1 (NT1) is a chronic neurological disorder having a strong association with HLA-DQB1*0602, thereby suggesting an immunological origin. Increased risk of NT1 has been reported among children or adolescents vaccinated with AS03 adjuvant-supplemented pandemic H1N1 influenza A vaccine, Pandemrix. Here we show that pediatric Pandemrix-associated NT1 patients have enhanced T-cell immunity against the viral epitopes, neuraminidase 175-189 (NA 175-189 ) and nucleoprotein 214-228 (NP 214-228 ), but also respond to a NA 175-189 -mimic, brain self-epitope, protein-O-mannosyltransferase 1 (POMT1 675-689 ). A pathogenic role of influenza virus-specific T-cells and T-cell cross-reactivity in NT1 are supported by the up-regulation of IFN-γ, perforin 1 and granzyme B, and by the converging selection of T-cell receptor TRAV10/TRAJ17 and TRAV10/TRAJ24 clonotypes, in response to stimulation either with peptide NA 175-189 or POMT1 675-689 . Moreover, anti-POMT1 serum autoantibodies are increased in Pandemrix-vaccinated children or adolescents. These results thus identify POMT1 as a potential autoantigen recognized by T- and B-cells in NT1.

An increased incidence of narcolepsy type 1 (NT1) was observed in Scandinavia following the 2009-2010 influenza Pandemrix vaccination. The association between NT1 and HLA-DQB1*06:02:01 supported the view of the vaccine as an etiological agent. A/H1N1 hemagglutinin (HA) is the main antigenic determinant of the host neutralization antibody response. Using two different immunoassays, the Luciferase Immunoprecipitation System (LIPS) and Radiobinding Assay (RBA), we investigated HA antibody levels and affinity in an exploratory and in a confirmatory cohort of Swedish NT1 patients and healthy controls vaccinated with Pandemrix. HA antibodies were increased in NT1 patients compared to controls in the exploratory (LIPS p = 0.0295, RBA p = 0.0369) but not in the confirmatory cohort (LIPS p = 0.55, RBA p = 0.625). HA antibody affinity, assessed by competition with Pandemrix vaccine, was comparable between patients and controls (LIPS: 48 vs. 39 ng/ml, p = 0.81; RBA: 472 vs. 491 ng/ml, p = 0.65). The LIPS assay also detected higher HA antibody titres as associated with HLA-DQB1*06:02:01 (p = 0.02). Our study shows that following Pandemrix vaccination, HA antibodies levels and affinity were comparable NT1 patients and controls and suggests that HA antibodies are unlikely to play a role in NT1 pathogenesis.

Background: Immune-related adverse events associated with immune checkpoint therapy cause autoimmune disease-like symptoms. People who carry specific genotypes or haplotypes of human leucocyte antigen (HLA) are known to be predisposed to develop autoimmune diseases including narcolepsy. Immunotherapy could be a trigger to develop narcolepsy in predisposing HLA positive patients., Case Presentation: A 66-year-old woman with stage IVB endometrial carcinosarcoma experienced daytime sleepiness and temporary muscle weakness 14 days after the administration of an immune checkpoint inhibitor, pembrolizumab. These were consistent with the main symptoms of narcolepsy with cataplexy. This patient carried a highly predisposing HLA haplotype for narcolepsy; HLA-DQB1*06:02, DRB1*15:01, DQA1*01:02 and DRB5*01:01:01. A hypocretin-1/orexin-A concentration in the patient's cerebrospinal fluid was low at 9.6 pg/mL in ELISA, and 155.5 pg/mL in radioimmunoassay that was below the normal level of 200 pg/mL. Therefore, she was diagnosed with narcolepsy tentatively according to the International Classification of Sleep Disorders, third edition diagnostic criteria for narcolepsy. The onset of narcolepsy in the 60s is very rare, and narcoleptic symptoms in our patient were likely to be caused by pembrolizumab., Conclusions: This case suggests that treatment with immune checkpoint inhibitors potentially causes narcolepsy in genetically predisposed patients., Competing Interests: Competing interests: SS reports grants and personal fees (lecture fee) from Chugai, grants and personal fees from Kyowa Kirin, grants and personal fees from Eli lilly, grants and personal fees from Astra Zeneca, personal fees from Pfizer, personal fees from MSD, grants and personal fees from Novartis, grants and personal fees from Eisai, grants and personal fees from Takeda and grants from Taiho, outside the submitted work. ET reports grants from Eli lilly, personal fees from Chugai, personal fees from Pfizer, personal fees from Novartis, outside the submitted work., (© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

This article evaluates the epidemiological evidence for a relationship between vaccination and neurological disease, specifically multiple sclerosis, Guillain-Barré syndrome and narcolepsy. The statistical methods used to test vaccine safety hypotheses are described and the merits of different study designs evaluated; these include the cohort, case-control, case-coverage and the self-controlled case-series methods. For multiple sclerosis, the evidence does not support the hypothesized relationship with hepatitis B vaccine. For Guillain-Barré syndrome, the evidence suggests a small elevated risk after influenza vaccines, though considerably lower than after natural influenza infection, with no elevated risk after human papilloma virus vaccine. For narcolepsy, there is strong evidence of a causal association with one adjuvanted vaccine used in the 2009/10 influenza pandemic. Rapid investigation of vaccine safety concerns, however biologically implausible, is essential to maintain public and professional confidence in vaccination programmes.

The incidence of narcolepsy type 1 (NT1) increased in Sweden following the 2009-2010 mass-vaccination with the influenza Pandemrix-vaccine. NT1 has been associated with Human leukocyte antigen (HLA) DQB1*06:02 but full high-resolution HLA-typing of all loci in vaccine-induced NT1 remains to be done. Therefore, here we performed HLA typing by sequencing HLA-DRB3, DRB4, DRB5, DRB1, DQA1, DQB1, DPA1 and DPB1 in 31 vaccine-associated NT1 patients and 66 of their first-degree relatives (FDR), and compared these data to 636 Swedish general population controls (GP). Previously reported disease-related alleles in the HLA-DRB5*01:01:01-DRB1*15:01:01-DQA1*01:02:01-DQB1*06:02:01 extended haplotype were increased in NT1 patients (34/62 haplotypes, 54.8%) compared to GP (194/1272 haplotypes, 15.3%, p = 6.17E-16). Indeed, this extended haplotype was found in 30/31 patients (96.8%) and 178/636 GP (28.0%). In total, 15 alleles, four extended haplotypes, and six genotypes were found to be increased or decreased in frequency among NT1 patients compared to GP. Among subjects with the HLA-DRB5*01:01:01-DRB1*15:01:01-DQA1*01:02-DQB1*06:02 haplotype, a second DRB4*01:03:01-DRB1*04:01:01-DQA1*03:02//*03:03:01-DQB1*03:01:01 haplotype (p = 2.02E-2), but not homozygosity for DRB1*15:01:01-DQB1*06:02:01 (p = 7.49E-1) conferred association to NT1. Alleles with increased frequency in DQA1*01:02:01 (p = 1.07E-2) and DQA1*03:02//*03:03:01 (p = 3.26E-2), as well as with decreased frequency in DRB3*01:01:02 (p = 8.09E-3), DRB1*03:01:01 (p = 1.40E-2), and DQB1*02:01:01 (p = 1.40E-2) were found among patients compared to their FDR. High-resolution HLA sequencing in Pandemrix-associated NT1 confirmed the strong association with the DQB1*06:02:01-containing haplotype but also revealed an increased association to the not previously reported extended HLA-DRB4*01:03:01-DRB1*04:01:01-DQA1*03:02//*03:03:01-DQB1*03:01:01 haplotype. High-resolution HLA typing should prove useful in dissecting the immunological mechanisms of vaccination-associated NT1., Competing Interests: The authors have declared that no competing interests exist.

A group of scientific and public health experts and key stakeholders convened to discuss the state of knowledge on the relationship between adjuvanted monovalent inactivated 2009 influenza A H1N1 vaccines used during the 2009 influenza pandemic and narcolepsy. There was consensus that an increased risk of narcolepsy was consistently observed after Pandemrix (AS03-adjuvanted) vaccine, but similar associations following Arepanrix (AS03-adjuvanted) or Focetria (MF59-adjuvanted) vaccines were not observed. Whether the differences are due to vaccine composition or other factors such as the timing of large-scale vaccination programs relative to H1N1pdm09 wild-type virus circulation in different geographic regions is not clear. The limitations of retrospective observational methodologies could also be contributing to some of the differences across studies. More basic and epidemiologic research is needed to further elucidate the association between adjuvanted influenza vaccine and narcolepsy and its mechanism and to inform planning and preparation for vaccination programs in advance of the next influenza pandemic., (Copyright © 2019.)

Study objectives: Narcolepsy type 1 (NT1) is a chronic sleep disorder characterized by loss of hypocretin-producing neurons. Increased NT1 incidence was observed in Sweden following mass-vaccination with Pandemrix ® . Genetic association to HLA DQB1*06:02 implies an autoimmune origin, but target autoantigen remains unknown. Candidate autoantigens for NT1 have previously been identified in solid-phase immunoassays, while autoantibodies against conformation-dependent epitopes are better detected in radiobinding assays. The aims are to determine autoantibody levels against nine candidate autoantigens representing (1) proteins of the hypocretin transmitter system; Preprohypocretin (ppHypocretin), Hypocretin peptides 1 and 2 (HCRT1 and HCRT2) and Hypocretin receptor 2 (HCRTR2); (2) proteins previously associated with NT1; Tribbles homologue 2 (TRIB2), Pro-opiomelanocortin/alpha-melanocyte-stimulating-hormone (POMC/α-MSH) and Prostaglandin D2 Receptor DP1 (DP1); (3) proteins suggested as autoantigens for multiple sclerosis (another HLA DQB1*06:02 -associated neurological disease); ATP-dependent Inwardly Rectifying Potassium Channel Kir4.1 (KIR4.1) and Calcium-activated chloride channel Anoctamin 2 (ANO2). Methods: Serum from post-Pandemrix ® NT1 patients ( n  = 31) and their healthy first-degree relatives ( n  = 66) were tested for autoantibody levels in radiobinding assays separating autoantibody bound from free labelled antigen with Protein A-Sepharose. 125 I-labelled HCRT1 and HCRT2 were commercially available while 35 S-methionine-labelled ppHypocretin, HCRTR2, TRIB2, α-MSH/POMC, DP1, KIR4.1 or ANO2 was prepared by in vitro transcription translation of respective cDNA. In-house standards were used to express data in arbitrary Units/ml (U/ml). Results: All radiolabelled autoantigens were detected in a concentration-dependent manner by respective standard sera. Levels of autoantibodies in the NT1 patients did not differ from healthy first-degree relatives in any of the nine candidate autoantigens. Conclusions: None of the nine labelled proteins proposed to be autoantigens were detected in the radiobinding assays for conformation-dependent autoantibodies. The results emphasise the need of further studies to identify autoantigen(s) and clarify the mechanisms in Pandemrix ® -induced NT1.

Background: In 2010, newly diagnosed narcolepsy cases among children and adolescents were seen in several European countries as a consequence of comprehensive national vaccination campaigns with Pandemrix against H1N1 influenza. Since then, a large number of people have had to live with narcolepsy and its consequences in daily life, such as effects on school life, social relationships, and activities. Initially, the adverse effects were not well understood and there was uncertainty about whether there would be any financial compensation. The situation remained unresolved until 2016, and during these years affected people sought various ways to join forces to handle the many issues involved, including setting up a social media forum., Objective: Our aim was to examine how information was shared, and how opinions and beliefs about narcolepsy as a consequence of Pandemrix vaccination were formed through discussions on social media., Methods: We used quantitative and qualitative methods to investigate a series of messages posted in a social media forum for people affected by narcolepsy after vaccination., Results: Group activity was high throughout the years 2010 to 2016, with peaks corresponding to major narcolepsy-related events, such as the appearance of the first cases in 2010, the first payment of compensation in 2011, and passage of a law on compensation in July 2016. Unusually, most (462/774, 59.7%) of the group took part in discussions and only 312 of 774 (40.3%) were lurkers (compared with the usual 90% rule of thumb for participation in an online community). The conversation in the group was largely factual and had a civil tone, even though there was a long struggle for the link between the vaccine and narcolepsy to be acknowledged and regarding the compensation issue. Radical, nonscientific views, such as those expounded by the antivaccination movement, did not shape the discussions in the group but were being actively expressed elsewhere on the internet. At the outset of the pandemic, there were 18 active Swedish discussion groups on the topic, but most dissolved quickly and only one Facebook group remained active throughout the period., Conclusions: The group studied is a good example of social media use for self-help through a difficult situation among people affected by illness and disease. This shows that social media do not by themselves induce trench warfare but, given a good group composition, can provide a necessary forum for managing an emergency situation where health care and government have failed or are mistrusted, and patients have to organize themselves so as to cope., (©Karin Blomberg, Mats Eriksson, Rickard Böö, Åke Grönlund. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 16.04.2019.)

Despite genetic and epidemiological evidence strongly supporting an autoimmune basis for narcolepsy type 1, the mechanisms involved have remained largely unknown. Here, we aimed to investigate whether the frequency and function of circulating follicular helper and follicular regulatory T cells are altered in narcolepsy type 1. Peripheral blood mononuclear cells were collected from 32 patients with narcolepsy type 1, including 11 who developed disease after Pandemrix ® vaccination, and 32 age-, sex-, and HLA-DQB1*06:02-matched healthy individuals. The frequency and phenotype of the different circulating B cell and follicular T cell subsets were examined by flow cytometry. The function of follicular helper T cells was evaluated by assessing the differentiation of naïve and memory B cells in a co-culture assay. We revealed a notable increase in the frequency of circulating B cells and CD4 + CXCR5 + follicular T cells in narcolepsy patients compared to age-, sex- and HLA-matched healthy controls. However, the inducible T-cell costimulator molecule, ICOS, was selectively down-regulated on follicular T cells from patients. Reduced frequency of activated ICOS + and PD1 high blood follicular T cells was also observed in the narcolepsy group. Importantly, follicular T cells isolated from patients with narcolepsy type 1 had a reduced capacity to drive the proliferation/survival and differentiation of memory B cells. Our results provide novel insights into the potential involvement of T cell-dependent B cell responses in the pathogenesis of narcolepsy type 1 in which down-regulation of ICOS expression on follicular helper T cells correlates with their reduced function. We hypothesize that these changes contribute to regulation of the deleterious autoimmune process after disease onset., (Copyright © 2018. Published by Elsevier Ltd.)

Objectives: To assess the number of Saudi patients diagnosed with narcolepsy in 2 tertiary centers before and after the introduction of the 2009 A(H1N1)pdm09 vaccine.  Methods: We started collecting data after the first international report of an association between the A(H1N1)pdm09 vaccine and narcolepsy between January 2010 and December 2016. All patients diagnosed with narcolepsy after 2009 were included and data were collected for 7 years to account for any possible delays in the diagnosis of narcolepsy.  Results: One-hundred and seventy-three patients with narcolepsy were identified. The majority (144 patients, 83%) had symptom onset before June 2009. Only 29 patients (17%) had symptom onset after 2009. No difference in the annual number of narcolepsy cases was found  before and after 2009. Conclusion: Based on data obtained from 2 tertiary care sleep disorders center, there was no increase in the number of cases of narcolepsy among Saudis following the introduction of the influenza A(H1N1)pdm09 vaccination.

Purpose: We aimed at investigating whether, in Germany, the number of individual case safety reports (ICSR) of confirmed narcolepsy following Pandemrix® vaccination notified to the Paul-Ehrlich-Institut (PEI, German Federal Institute for Vaccines and Biomedicines) was higher than expected when compared with the prepandemic background incidence rates., Methods: ICSR of narcolepsy after vaccination with Pandemrix® notified to the PEI until September 2016 were reviewed and validated according to the criteria of narcolepsy defined by the Brighton Collaboration (BC). Cases fulfilling the criteria of BC levels of diagnostic certainty 1 to 4a with symptoms onset after vaccination with Pandemrix® were eligible. Adjustment for underreporting was performed with cases of narcolepsy recruited within the scope of the German Narcolepsy Study using capture-recapture methods. An observed versus expected (OvE) analysis was conducted based on adjusted case numbers using risk windows for symptoms onset within 4 and 6 months following vaccination., Results: By the end of September 2016, a total of 85 ICSR of narcolepsy after vaccination with Pandemrix® had been notified to the PEI 52 of which were eligible. The OvE estimates for the 4 and 6 months risk windows were 3.8 (95% CI: 2.6-5.4) and 2.8 (95% CI: 2.0-3.9), respectively. The number of excess cases was higher in children and adolescents (15-fold and 11.7-fold increased OvE estimate) than in adults (2.1-fold and 1.5-fold increased estimate)., Conclusions: Compared with the prepandemic background incidence rate, the number of incident narcolepsy cases was 3.8-fold and 2.8-fold as high., (Copyright © 2017 John Wiley & Sons, Ltd.)

Background: Patients with narcolepsy type 1 (NT1) show alterations in sleep stage transitions, rapid-eye-movement (REM) and non-REM sleep due to the loss of hypocretinergic signaling. However, the sleep microstructure has not yet been evaluated in these patients. We aimed to evaluate whether the sleep spindle (SS) density is altered in patients with NT1 compared to controls and patients with narcolepsy type 2 (NT2)., Methods: All-night polysomnographic recordings from 28 NT1 patients, 19 NT2 patients, 20 controls (C) with narcolepsy-like symptoms, but with normal cerebrospinal fluid hypocretin levels and multiple sleep latency tests, and 18 healthy controls (HC) were included. Unspecified, slow, and fast SS were automatically detected, and SS densities were defined as number per minute and were computed across sleep stages and sleep cycles. The between-cycle trends of SS densities in N2 and NREM sleep were evaluated within and between groups., Results: Between-group comparisons in sleep stages revealed no significant differences in any type of SS. Within-group analyses of the SS trends revealed significant decreasing trends for NT1, HC, and C between first and last sleep cycle. Between-group analyses of SS trends between first and last sleep cycle revealed that NT2 differ from NT1 patients in the unspecified SS density in NREM sleep, and from HC in the slow SS density in N2 sleep., Conclusions: SS activity is preserved in NT1, suggesting that the ascending neurons to thalamic activation of SS are not significantly affected by the hypocretinergic system. NT2 patients show an abnormal pattern of SS distribution., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The influenza A(H1N1)pdm09 vaccination campaign from 2009 to 2010 was associated with a sudden increase in the incidence of narcolepsy in several countries. Narcolepsy with cataplexy is strongly associated with the human leukocyte antigen (HLA) class II DQB1*06:02 allele, and protective associations with the DQB1*06:03 allele have been reported. Several non-HLA gene loci are also associated, such as common variants of the T-cell receptor-α (TRA), the purinergic receptor P2RY11, cathepsin H (CTSH) and TNFSF4/OX40L/CD252. In this retrospective multicenter study, we investigated if these predisposing gene loci were also involved in vaccination-associated narcolepsy. We compared HLA- along with single-nucleotide polymorphism genotypes for non-HLA regions between 42 Pandemrix-vaccinated narcolepsy cases and 1990 population-based controls. The class II gene loci associations supported previous findings. Nominal association (P-value<0.05) with TRA as well as suggestive (P-value<0.1) associations with P2RY11 and CTSH were found. These associations suggest a very strong gene-environment interaction, in which the influenza A(H1N1)pdm09 strain or Pandemrix vaccine can act as potent environmental triggers.

We previously reported an increased frequency of antibodies to hypocretin (HCRT) receptor 2 in sera obtained from narcoleptic patients who received the European AS03-adjuvanted vaccine Pandemrix (GlaxoSmithKline Biologicals, s.a.) for the global influenza A H1N1 pandemic in 2009 [A(H1N1)pdm09]. These antibodies cross-reacted with a particular fragment of influenza nucleoprotein (NP) - one of the proteins naturally contained in the virus used to make seasonal influenza vaccine and pandemic influenza vaccines. The purpose of this commentary is to provide additional insights and interpretations of the findings and share additional data not presented in the original paper to help the reader appreciate the key messages of that publication. First, a brief background to narcolepsy and vaccine-induced narcolepsy will be provided. Then, additional insights and clarification will be provided on the following topics: 1) the critical difference identified in the adjuvanted A(H1N1)pdm09 vaccines, 2) the contributing factor likely for the discordant association of narcolepsy between the AS03-adjuvanted pandemic vaccines Pandemrix and Arepanrix (GlaxoSmithKline Biologicals, s.a.), 3) the significance of detecting HCRT receptor 2 (HCRTr2) antibodies in some Finnish control subjects, 4) the approach used for the detection of HCRTr2 antibodies in vaccine-associated narcolepsy, and 5) the plausibility of the proposed mechanism involving HCRTr2 modulation in vaccine-associated narcolepsy.

Introduction: Narcolepsy type 1 is an organic sleep disorder caused by the destruction of hypocretin producing neurons in hypothalamus. In addition to daytime sleepiness, the spectrum and severity of symptoms are very variable. Psychiatric comorbidity and phenomena resembling psychotic symptoms are also common. Current treatment options for narcolepsy are symptomatic but there are few case reports of positive effect of immunotherapy. We report a very severely affected young boy treated with rituximab (RXB)., Case Report: A 12-year-old boy developed narcolepsy after Pandemrix H1N1 vaccination in 2010. He started to express severe psychiatric symptoms shortly after the onset. Cataplexy and sleepiness were devastatingly disabling. Conventional treatments did not have any effect on symptoms so we decided to try RXB, chimeric human monoclonal antibody against CD20 expressed in B lymphocytes. After the first treatment his condition ameliorated dramatically. Unfortunately, the effect lasted only for 2 months. Following attempts did not show any effect., Conclusions: Effect of RXB on narcolepsy has not been reported before. Remarkable but short-lasting effect of RXB in narcolepsy is intriguing as it could imply that there is still ongoing B cell-mediated autoimmune response possible contributing to symptoms in narcolepsy.

Several studies have identified an association between Pandemrix(TM), an AS03 adjuvanted pandemic influenza A(H1N1) vaccine, and narcolepsy, a rare and under-diagnosed sleep disorder with a median onset-to-diagnosis interval of ten years. This paper reviews potential sources of bias in published studies and aims to provide, through simulation, methodological recommendations for assessment of vaccine safety signals. Our simulation study showed that in the absence of an association between the vaccine and the outcome, presence of detection bias and differential exposure misclassification could account for elevated risk estimates. These may play a major role, particularly in alert situations when observation times are limited and the disease has a long latency period. Estimates from the case-control design were less inflated than those from the cohort design when these biases were present. Overall, these simulations provide useful insights for the design and interpretation of future studies.

Background: An increase in narcolepsy cases was observed in Finland and Sweden towards the end of the 2009 H1N1 influenza pandemic. Preliminary observational studies suggested a temporal link with the pandemic influenza vaccine Pandemrix™, leading to a number of additional studies across Europe. Given the public health urgency, these studies used readily available retrospective data from various sources. The potential for bias in such settings was generally acknowledged. Although generally advocated by key opinion leaders and international health authorities, no systematic quantitative assessment of the potential joint impact of biases was undertaken in any of these studies., Methods: We applied bias-level multiple-bias analyses to two of the published narcolepsy studies: a pediatric cohort study from Finland and a case-control study from France. In particular, we developed Monte Carlo simulation models to evaluate a potential cascade of biases, including confounding by age, by indication and by natural H1N1 infection, selection bias, disease- and exposure misclassification. All bias parameters were evidence-based to the extent possible., Results: Given the assumptions used for confounding, selection bias and misclassification, the Finnish rate ratio of 13.78 (95% CI: 5.72-28.11) reduced to a median value of 6.06 (2.5th- 97.5th percentile: 2.49-15.1) and the French odds ratio of 5.43 (95% CI: 2.6-10.08) to 1.85 (2.5th-97.5th percentile: 0.85-4.08)., Conclusion: We illustrate multiple-bias analyses using two studies on the Pandemrix™-narcolepsy association and advocate their use to better understand the robustness of study findings. Based on our multiple-bias models, the observed Pandemrix™-narcolepsy association consistently persists in the Finnish study. For the French study, the results of our multiple-bias models were inconclusive.

A link between Pandemrix™ (AS03-adjuvanted H1N1 pandemic influenza vaccine, GSK Vaccines, Belgium) and narcolepsy was first suspected in 2010 in Sweden and Finland following a number of reports in children and adolescents. Initial scepticism about the reported association faded as additional countries reported similar findings, leading several regulatory authorities to restrict the use of Pandemrix™. The authors acknowledge that currently available data suggest an increased risk of narcolepsy following vaccination with Pandemrix™; however, from an epidemiologist's perspective, significant methodological limitations of the studies have not been fully addressed and raise questions about the reported risk estimates. We review the most important biases and confounders that potentially occurred in 12 European studies of the observed association between Pandemrix™ and narcolepsy, and call for further analyses and debate.

During the swine flu pandemic of 2009-2010, all Swedish citizens were recommended to be vaccinated with the influenza vaccine Pandemrix. However, a very serious and unexpected side effect emerged during the summer of 2010: more than 200 children and young adults were diagnosed with narcolepsy after vaccination. Besides the tragic outcome for these children and their families, this adverse side effect suggests future difficulties in obtaining trust in vaccination in cases of emerging pandemics, and thus there is a growing need to find ways to understand the complexities of vaccination decision processes. This article explores written responses to a questionnaire from a Swedish folk life archive as an unconventional source for analysing vaccine decisions. The aim is to investigate how laypersons responded to and re-interpreted the message about the recommended vaccination in their answers. The answers show the confusion and complex circumstances and influences in everyday life that people reflect on when making such important decisions. The issue of confusion is traced back to the initial communications about the vaccination intervention in which both autonomy and solidarity were expected from the population. Common narratives and stories about the media or 'big pharma capitalism' are entangled with private memories, accidental coincidences and serendipitous associations. It is obvious that vaccination interventions that require compliance from large groups of people need to take into account the kind of personal experience narratives that are produced by the complex interplay of the factors described by the informants., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)

Background: Previous reports mostly from Europe suggested an association between an occurrence of narcolepsy and an influenza A(H1N1)pdm09 vaccine adjuvanted with AS03 (Pandemrix(®)). During the 2009 H1N1 pandemic vaccination campaign, the Korean military performed a vaccination campaign with one type of influenza vaccine containing MF59-adjuvants. This study was conducted to investigate the background incidence rate of narcolepsy in South Korean soldiers and the association of the MF59-adjuvanted vaccine with the occurrence of narcolepsy in a young adult group., Methods: To assess the incidence of narcolepsy, we retrospectively reviewed medical records of suspicious cases of narcolepsy in 2007-2013 in the whole 20 military hospitals of the Korean military. The screened cases were classified according to the Brighton Collaboration case definition of narcolepsy. After obtaining the number of confirmed cases of narcolepsy per 3 months in 2007-2013, we compared the crude incidence rate of narcolepsy before and after the vaccination campaign., Results: We included 218 narcolepsy suspicious cases in the initial review, which were screened by the diagnostic code on the computerized disease registry in 2007-2013. Forty-one cases were finally diagnosed with narcolepsy in 2007-2013 (male sex, 95%; median age, 21 years). The average background incidence rate of narcolepsy in Korean soldiers was 0.91 cases per 100,000 persons per year. During the 9 months before vaccination implementation (April to December 2009), 6 narcolepsy cases occurred, whereas during the next 9 months (January to September 2010) including the 3-month vaccination campaign, 5 cases occurred., Conclusions: The incidence of narcolepsy in South Korean soldiers was not increased after the pandemic vaccination campaign using the MF59-adjuvanted vaccine. Our results suggest that the MF59-adjuvanted H1N1 vaccine did not contribute to the occurrence of narcolepsy in this young adult group., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

A safety signal around Pandemrix, an AS03 adjuvanted influenza A(H1N1) pdm09 vaccine potentially causing narcolepsy in children and adolescents became public in August 2010, long after cessation of the influenza A(H1N1) pdm09 campaigns in Europe. The signal originated from Finland and Sweden, two countries with school based pandemic vaccination campaigns, with high vaccine coverage, and vaccinations being provided at the peak of the circulating wild virus. Since the announcement awareness grew in Europe, with extensive public media dissemination and regulatory actions. This resulted in a steep increase in the spontaneous reports of exposed cases, a decrease in diagnostic lag times of this rare, underdiagnosed disease and finally victim compensation. The signaling countries conducted rapid risk assessment studies to quantify the signal to the best of their abilities, in the midst of the public awareness, most of which could not distinguish between a vaccine and an awareness effect. Due to the strong but variable associations from the epidemiological studies, the search for biological mechanisms started. Currently it is not yet understood how Pandemrix might cause narcolepsy, and whether it would be specific to Pandemrix. The paper describes the current evidence and puts forward the questions that remain to be answered, which are relevant for future pandemic preparedness when adjuvants may be used for dose sparing., (Copyright © 2015. Published by Elsevier Ltd.)

Objectives: Antidepressants substantially affect REM sleep characteristics and trigger manifestations of REM sleep behavior disorder (RBD) in the general, non-narcoleptic, population. Antidepressants are also frequently administrated in an attempt to suppress cataplexy. We investigated the role of antidepressants in the development of RBD in narcolepsy with cataplexy (NC) patients., Patients/methods: Seventy-five patients diagnosed with NC were assessed by a structured interview (focused on RBD manifestations and the use of antidepressants) and night video-polysomnography followed by the multiple sleep latency test., Results: Of all 75 NC patients (36 male, 39 female; mean age 46.1±18.5 years), 34 cases had a history of antidepressant use (45.3%; 18 male, 16 female). In this antidepressant-positive group, 13 patients suffered from RBD (38.2%). Among antidepressant-naïve patients, only 5 subjects (12.2%) were diagnosed with RBD. Polysomnographic data showed significantly increased REM latency (p<0.01) and reduced percentage of REM sleep (p<0.01) in the antidepressant-positive group, as well as more periodic limb movements during sleep (p=0.01)., Conclusions: NC patients with a history of antidepressant use showed a three-fold higher occurrence of RBD in comparison to antidepressant-naïve patients.

Purpose of Review: Sleep problems in adolescents are very common and negatively impact the quality of their health and lives, yet often go undiagnosed. This review is meant to familiarize pediatricians with some of the more commonly encountered sleep disorders in this age group, and to review their diagnosis and management., Recent Findings: Recent findings reinforce the ubiquity of insufficient and poor-quality sleep in teens and their consequences on physical and mental health, cognition, and behavior. Increasing use of technology by teens, especially at night, plays a growing role in this. Parentally set bedtimes can be effective in increasing the sleep duration, thereby diminishing the consequences of insufficient sleep. Parasomnias, common in early childhood, usually diminish with the transition into adolescence. An almost 10-fold increase in the incidence of narcolepsy has been reported following the use of one type of vaccination against influenza H1N1 in Europe. Recent guidelines for the diagnosis and management of obstructive sleep apnea are reviewed, as are recent guidelines pertaining to the management of sleep disorders of children on the autism spectrum., Summary: Sleep disorders in adolescents are both very common and underdiagnosed, adversely affecting their overall well being.

Background: After the H1N1 swine flu vaccination campaign an increased number of narcolepsy cases in children and adolescents was observed in Scandinavian and later in further European countries that correlated with the vaccination by an AS03-adjuvanted influenza vaccine (Pandemrix). Narcolepsy is a chronic sleep disorder characterized by the loss of hypocretin in the cerebrospinal fluid due to selective destruction of hypocretin-producing neurons in the perifornical hypothalamus. In >99% of the cases narcolepsy is associated with the HLA-subtype DQB1*602 giving the link to an autoimmune process. In contrast to other squalene-based adjuvants, for which no association with narcolepsy was reported so far, ASO3 contains in addition α-tocopherol. It could be observed recently that α-tocopherol activates the transcription factor Nrf2. Nrf2 triggers the expression of cytoprotective genes, i.e. the catalytic active subunits of the constitutive proteasome, by binding to the antioxidant response element (ARE). It was hypothesized that α-tocopherol via activation of Nrf2 affects expression and turnover of hypocretin, leading to an increased amount of hypocretinα-specific fragments that bind to DQB1*602., Results: α-Tocopherol activates Nrf2 in neuronal cells in vitro. Promoter analysis revealed an ARE sequence in the hypocretin promoter. Indeed, α-tocopherol increases by activation of Nrf2 the expression of hypocretin. In parallel, α-tocopherol -dependent induction of Nrf2 augments expression of catalytic subunits of the proteasome leading to increased degradation of hypocretin. Moreover, elevated activation of Nrf2 is associated with a decreased activity of NF-κB that results in an increased sensitivity to apoptotic stimuli., Conclusion: In case of a genetic predisposition (DQB1*602) α-tocopherol could confer to development of narcolepsy by activation of Nrf2 that finally leads to an elevated formation of longer hypocretin-derived fragments that can be presented by HLA-subtype DQB1*602. These cells are recognized by the immune system and due to their increased sensitivity to apoptotic stimuli they can be destroyed, finally leading to a lack of hypocretin., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Narcolepsy is a lifelong sleep disorder related to hypocretin deficiency resulting from a specific loss of hypocretin-producing neurons in the lateral hypothalamic area. The disease is thought to be autoimmune due to a strong association with HLA-DQB1*06:02. In 2009 the World Health Organization (WHO) declared the H1N1 2009 flu pandemic (A/H1N1PDM09). In response to this, the Swedish vaccination campaign began in October of the same year, using the influenza vaccine Pandemrix(®). A few months later an excess of narcolepsy cases was observed. It is still unclear to what extent the vaccination campaign affected humoral autoimmunity associated with narcolepsy. We studied 47 patients with narcolepsy (6-69 years of age) and 80 healthy controls (3-61 years of age) selected after the Pandemrix vaccination campaign. The first aim was to determine antibodies against A/H1N1 and autoantibodies to Tribbles homolog 2 (TRIB2), a narcolepsy autoantigen candidate as well as to GAD65 and IA-2 as disease specificity controls. The second aim was to test if levels and frequencies of these antibodies and autoantibodies were associated with HLA-DQB1*06:02. In vitro transcribed and translated [(35)S]-methionine and -cysteine-labeled influenza A virus (A/California/04/2009/(H1N1)) segment 4 hemagglutinin was used to detect antibodies in a radiobinding assay. Autoantibodies to TRIB2, GAD65 and IA-2 were similarly detected in standard radiobinding assays. The narcolepsy patients had higher median levels of A/H1N1 antibodies than the controls (p = 0.006). A/H1N1 antibody levels were higher among the <13 years old (n = 12) compared to patients who were older than 30 years (n = 12, p = 0.014). Being HLA-DQB1*06:02 positive was associated with higher A/H1N1 antibody levels in both patients and controls (p = 0.026). Serum autoantibody levels to TRIB2 were low overall and high binders did not differ between patients and controls. We observed an association between levels of A/H1N1 antibodies and TRIB2 autoantibody levels particularly among the youngest narcolepsy patients (r = 0.819, p < 0.001). In conclusion, following the 2009 influenza pandemic vaccination, A/H1N1 antibody levels were associated with young age-at-onset narcolepsy patients positive for HLA-DQB1*06:02. The possibility that TRIB2 is an autoantigen in narcolepsy remains to be clarified. We could verify autoantibody responses against TRIB2 which needs to be determined in larger patient cohorts and control populations., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The vaccine safety surveillance system effectively detected a very rare adverse event, narcolepsy, in subjects receiving AS03-adjuvanted A(H1N1) pandemic vaccine made using the European inactivation/purification protocol. The reports of increased cases of narcolepsy in non-vaccinated subjects infected with wild A(H1N1) pandemic influenza virus suggest a role for the viral antigen(s) in disease development. However, additional investigations are needed to better understand what factor(s) in wild influenza infection trigger(s) narcolepsy in susceptible hosts. An estimated 31 million doses of European AS03-adjuvanted A(H1N1) pandemic vaccine were used in more than 47 countries. The Canadian AS03-adjuvanted A(H1N1) pandemic vaccine was used with high coverage in Canada where an estimated 12 million doses were administered. As no similar narcolepsy association has been reported to date with the AS03-adjuvanted A(H1N1) pandemic vaccine made using the Canadian inactivation/purification protocol, this suggests that the AS03 adjuvant alone may not be responsible for the narcolepsy association. To date, no narcolepsy association has been reported with the MF59®-adjuvanted A(H1N1) pandemic vaccine. This review article provides a brief background on narcolepsy, outlines the different types of vaccine preparations including the ones for influenza, reviews the accumulated evidence for the safety of adjuvants, and explores the association between autoimmune diseases and natural infections. It concludes by assimilating the historical observations and recent clinical studies to formulate a feasible hypothesis on why vaccine-associated narcolepsy may not be solely linked to the AS03 adjuvant but more likely be linked to how the specific influenza antigen component of the European AS03-adjuvanted pandemic vaccine was prepared. Careful and long-term epidemiological studies of subjects who developed narcolepsy in association with AS03-adjuvanted A(H1N1) pandemic vaccine prepared with the European inactivation/purification protocol are needed., (Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Objectives: We aimed to compare post-Pandemrix vaccination (postvaccine) childhood narcolepsy with cataplexy (NC) vs. sporadic pre-H1N1 pandemic (pre-H1N1) cases., Methods: Clinical, anthropometric, polysomnographic, and cerebrospinal hypocretin 1 (hcrt-1) measurements were collected together with the video recordings of cataplexy in 27 Finnish patients with NC onset after H1N1 Pandemrix vaccination (mean age, 12±4 years; 52% boys) and 42 Italian NC patients with NC onset before the H1N1 pandemic (mean age, 11±3 years; 48% boys). All subjects carried the HLA-DQB1*0602 allele., Results: Postvaccine subjects were older at NC onset (12±3 vs. 9±3 years; P=.008) and displayed a shorter mean sleep latency in multiple sleep latency tests (MSLT) (2.3±2.2 vs. 3.7±2.9 min; P=.026) compared to pre-H1N1 cases. Anthropometric, clinical (core NC symptoms), hcrt-1 deficiency, and polysomnographic data did not differ among groups, but higher disrupted nocturnal sleep was observed in postvaccine subjects. Comparison of cataplexy features at video assessment showed an overlapping picture with the exception for hyperkinetic movements which appeared to be more evident in pre-H1N1 subjects., Conclusions: The clinical picture of childhood NC was similar in postvaccine and pre-H1N1 children., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Objectives: To investigate the association between vaccination with Pandemrix and risk of selected neurological and immune-related diseases including narcolepsy., Design: Population-based prospective cohort study using data from regional vaccination registries and national health registries., Setting: Seven healthcare regions in Sweden comprising 61% of the Swedish population., Subjects: Study population of 3,347,467 vaccinated and 2,497,572 nonvaccinated individuals (vaccination coverage ≈ 60%) followed between 2009 and 2011 for 6.9 million person-years after exposure and 6.0 million person-years without exposure., Main Outcome Measure and Analysis: First recorded diagnosis of neurological and immune-related diseases. Relative risks [hazard ratios (HRs) with 95% confidence intervals (CIs)] assessed using Cox regression, adjusted for covariates., Results: For all selected neurological and immune-related outcomes under study, other than allergic vaccine reactions (for which we verified an expected increase in risk) and narcolepsy, HRs were close to 1.0 and always below 1.3. We observed a three-fold increased risk of a diagnosis of narcolepsy (HR: 2.92, 95% CI: 1.78-4.79; that is, four additional cases per 100,000 person-years) in individuals ≤ 20 years of age at vaccination and a two-fold increase (HR: 2.18, 95% CI: 1.00-4.75) amongst young adults between 21 and 30 years of age. The excess risk declined successively with increasing age at vaccination; no increase in risk was seen after 40 years of age., Conclusions: For a large number of selected neurological and immune-related diseases, we could neither confirm any causal association with Pandemrix nor refute entirely a small excess risk. We confirmed an increased risk for a diagnosis of narcolepsy in individuals ≤ 20 years of age and observed a trend towards an increased risk also amongst young adults between 21 and 30 years., (© 2013 The Association for the Publication of the Journal of Internal Medicine.)

Epidemiological data from several European countries suggested an increased risk of the chronic sleep disorder narcolepsy following vaccination with Pandemrix(™), an AS03-adjuvanted, pandemic A(H1N1)pdm09 influenza vaccine. Further research to investigate potential associations between Pandemrix™ vaccination, A(H1N1)pdm09 influenza infection and narcolepsy is required. Narcolepsy is most commonly caused by a reduction or absence of hypocretin produced by hypocretin-secreting neurons in the hypothalamus, and is tightly associated with HLA-II DQB1*06:02. Consequently, research focusing on CD4(+) T-cell responses, building on the hypothesis that for disease development, T cells specific for antigen(s) from hypocretin neurons must be activated or reactivated, is considered essential. Therefore, the following key areas of research can be identified, (1) characterization of hypothetical narcolepsy-specific auto-immune CD4(+) T cells, (2) mapping epitopes of such T cells, and (3) evaluating potential mechanisms that would enable such cells to gain access to the hypothalamus. Addressing these questions could further our understanding of the potential links between narcolepsy and A(H1N1)pdm09 vaccination and/or infection. Of particular interest is that any evidence of a mimicry-based mechanism could also explain the association between narcolepsy and A(H1N1)pdm09 influenza infection.

Purpose of Review: A number of European countries have reported a dramatic increase in the rates of childhood narcolepsy with cataplexy in children immunized with a split-virion adjuvanted swine flu vaccine. Here, we review the strengths and weaknesses of these epidemiological studies and possible neuroimmunological mechanisms., Recent Findings: Initial concerns of a 13-fold increased relative risk of narcolepsy were raised by the Scandinavian health protection agencies in 2010. Subsequent retrospective studies support these findings in Canada, France, Ireland, England and Denmark. The cases are predominantly young children who present with severe and rapid onset of cataplexy as well as narcolepsy often within a few weeks of vaccination. The proposed mechanism for postvaccination narcolepsy is one in which an environmental trigger causes or enhances an antibody-mediated autoimmune response in patients with a preexisting genetic susceptibility. However, there have not yet been any reports of specific autoimmunity, either antibody or T-cell-mediated., Summary: There is a strong association between narcolepsy and H1N1 vaccination. However, whether this reflects a true increase in affected individuals or a hastening of disease onset in individuals who would otherwise have developed narcolepsy later will become clear in the coming years. The pathological explanation of this association and narcolepsy is likely to be autoimmune, although supportive evidence is lacking.Video abstract available: See the Video Supplementary Digital Content 1 (http://links.lww.com/COPM/A9).