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Background: GLP-1 receptor agonists have neurotrophic properties in in-vitro and in-vivo models of Parkinson's disease and results of epidemiological studies and small randomised trials have suggested possible benefits for risk and progression of Parkinson's disease. We aimed to establish whether the GLP-1 receptor agonist, exenatide, could slow the rate of progression of Parkinson's disease., Methods: We did a phase 3, multicentre, double-blind, parallel-group, randomised, placebo-controlled trial at six research hospitals in the UK. Participants were aged 25-80 years with a diagnosis of Parkinson's disease, were at Hoehn and Yahr stage 2·5 or less when on dopaminergic treatment, and were on dopaminergic treatment for at least 4 weeks before enrolment. Participants were randomly assigned (1:1) using a web-based system with minimisation according to Hoehn and Yahr stage and study site to receive extended-release exenatide 2 mg by subcutaneous pen injection once per week over 96 weeks, or visually identical placebo. All participants and all research team members at study sites were masked to randomisation allocation. The primary outcome was the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III score, off dopaminergic medication at 96 weeks, analysed in the intention-to-treat population using a linear mixed modelling approach. This study is registered with ISRCTN (14552789), EudraCT (2018-003028-35), and ClinicalTrials.gov (NCT04232969)., Findings: Between Jan 23, 2020, and April 23, 2022, 215 participants were screened for eligibility, of whom 194 were randomly assigned to exenatide (n=97) or placebo (n=97). 56 (29%) participants were female and 138 (71%) were male. 92 participants in the exenatide group and 96 in the placebo group had at least one follow-up visit and were included in analyses. At 96 weeks, MDS-UPDRS III OFF-medication scores had increased (worsened) by a mean of 5·7 points (SD 11·2) in the exenatide group, and by 4·5 points (SD 11·4) points in the placebo group (adjusted coefficient for the effect of exenatide 0·92 [95% CI -1·56 to 3·39]; p=0·47). Nine (9%) participants in the exenatide group had at least one serious adverse event compared with 11 (11%) in the placebo group., Interpretation: Our findings suggest that exenatide is safe and well tolerated. We found no evidence to support exenatide as a disease-modifying treatment for people with Parkinson's disease. Studies with agents that show better target engagement or in specific subgroups of patients are needed to establish whether there is any support for the use of GLP-1 receptor agonists for Parkinson's disease., Funding: National Institute for Health and Care Research and Cure Parkinson's., Competing Interests: Declaration of interests TF has received grants from the National Institute of Health Research, Edmond J Safra Foundation, Michael J Fox Foundation, John Black Charitable Foundation, Cure Parkinson's, Innovate UK, Janet Owens Research Fellowship, Rosetrees Trust, Van Andel Research Institute, and Defeat MSA; has served on advisory boards for Peptron, Voyager Therapeutics, Handl Therapeutics, Gain Therapeutics, Living Cell Technologies, AbbVie, Bluerock, Bayer, and Bial; and has received honoraria for talks sponsored by Bayer, Bial, Profile Pharma, Boston Scientific, and Novo Nordisk. CC has received advisory, consulting, or lecture fees from AbbVie, Bial, Britannia, Scient, Global Kinetics, Kyowa Kirin, Medscape, Mission Therapeutics, MODAG, and Roche, and research funding from Parkinson's UK, Edmond J Safra Foundation, National Institute of Health and Care Research, and Cure Parkinson's. MS has received grants from Parkinson's UK, Michael J Fox Foundation, and Medical Research Council; and has received honoraria for lecturing and consulting from Bial and Medtronic. DA has received grant funding from Cure Parkinson's, the National Institute for Health Research, and Medical Research Council Clinical Academic Research Partnership. EJ has received grant funding from Progressive Supranuclear Palsy Association, Cure Progressive Supranuclear Palsy, and Medical Research Council. GD has received honoraria for talks sponsored by GE Healthcare and AbbVie and support from Bial. JD has received consulting fees from Clario. HMo has received funding from Michael J Fox Foundation, Cure Parkinson's, Progressive Supranuclear Palsy Association, Corticobasal Degeneration Solutions, Drake Foundation, Parkinson's UK, and the Medical Research Council; has received consulting fees from Roche, Amylyx, and Aprinoia; and has received honoraria for speaking at meetings supported by Kyowa Kirin, The British Medical Journal, and Movement Disorders Society. All other authors declare no competing interests., (Copyright © 2025 Elsevier Ltd. All rights reserved.)

Background: Subthalamic (STN) and pallidal (GPi) deep brain stimulation (DBS) improve quality of life, motor, and nonmotor symptoms (NMS) in advanced Parkinson's disease (PD). However, few studies have compared their nonmotor effects., Objective: To compare nonmotor effects of STN-DBS and GPi-DBS., Methods: In this prospective, observational, multicenter study including 60 PD patients undergoing bilateral STN-DBS (n = 40) or GPi-DBS (n = 20), we examined PDQuestionnaire (PDQ), NMSScale (NMSS), Unified PD Rating Scale-activities of daily living, -motor impairment, -complications (UPDRS-II, -III, -IV), Hoehn&Yahr, Schwab&England Scale, and levodopa-equivalent daily dose (LEDD) preoperatively and at 6-month follow-up. Intra-group changes at follow-up were analyzed with Wilcoxon signed-rank or paired t-test, if parametric tests were applicable, and corrected for multiple comparisons. Inter-group differences were explored with Mann-Whitney-U/unpaired t-tests. Analyses were performed before and after propensity score matching which balanced out demographic and preoperative clinical characteristics. Strength of clinical changes was assessed with effect size., Results: In both groups, PDQ, UPDRS-II, -IV, Schwab&England Scale, and NMSS improved significantly at follow-up. STN-DBS was significantly better for LEDD reduction, GPi-DBS for UPDRS-IV. While NMSS total score outcomes were similar, explorative NMSS domain analyses revealed distinct profiles: Both targets improved sleep/fatigue and mood/cognition, but only STN-DBS the miscellaneous (pain/olfaction) and attention/memory and only GPi-DBS cardiovascular and sexual function domains., Conclusions: To our knowledge, this is the first study to report distinct patterns of beneficial nonmotor effects of STN-DBS and GPi-DBS in PD. This study highlights the importance of NMS assessments to tailor DBS target choices to patients' individual motor and nonmotor profiles., Competing Interests: Declaration of competing interest Keyoumars Ashkan has received honoraria for educational meetings, travel and consultancy from Medtronic and Boston Scientific which manufacture deep brain stimulation systems used in this study. Monty Silverdale reports no potential conflict of interest. Julian Evans reports no potential conflict of interest. Raquel C.R. Martinez reports no potential conflict of interest. Rubens G. Cury reports no potential conflict of interest. Stefanie T. Jost reports no potential conflict of interest. Michael T. Barbe reports grants from Boston Scientific and Medtronic which manufacture deep brain stimulation systems used in this study. Gereon R. Fink reports no potential conflict of interest. Angelo Antonini reports personal consultancy fees from Medtronic and Boston Scientific which manufacture deep brain stimulation systems used in this study. K. Ray Chaudhuri reports no potential conflict of interest. Pablo Martinez-Martin reports no potential conflict of interest. Erich Talamoni Fonoff is a consultant for Medtronic and Boston Scientific which manufacture deep brain stimulation systems used in this study. Lars Timmermann reports grants, personal fees and nonfinancial support from Medtronic and Boston Scientific which manufacture deep brain stimulation systems used in this study. This paper is independent research funded by the German Research Foundation (Grant KFO 219), the National Institute of Health Research (NIHR) Mental Health Biomedical Research Centre and Dementia Unit at South London and Maudsley NHS Foundation Trust and King’s College London. Additionally, an unrestricted peer reviewed educational grant was provided to support coordination of the UK dataset from Medtronic., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)

Objective: The optimal timing of subthalamic nucleus (STN) deep brain stimulation (DBS) in Parkinson's disease (PD) is a topic of ongoing debate. In patients with short disease duration an improvement of quality of life (QoL) has been demonstrated for patients aged younger than 61 years. However, this has not been systematically investigated in older patients yet. We hypothesized that patients aged 61 years or older experience a significant QoL improvement after STN-DBS with no difference in effect sizes for groups of patients with short and longer disease duration., Materials and Methods: From four centers (Cologne, London, Manchester, Venice) we identified "older patients" aged 61 years or older with short (≤8 years) or longer disease duration and compared QoL, motor impairment, complications, medication requirements, and Mini-Mental State Examination (MMSE) on baseline and five months after surgery., Results: Mean age/disease duration in 21 subjects with shorter disease duration were 65.5/6.3 years compared to 66.8/14.6 in 33 subjects with longer disease duration. The short disease duration group was affected by less baseline motor complications (p = 0.002). QoL in the short/longer disease duration group improved by 35/20% (p = 0.010/p = 0.006), motor complications by 40/44% (p = 0.018/p < 0.001), and medication requirements by 51/49% (both p < 0.001). MMSE remained unchanged in both groups., Conclusion: Patients aged 61 years or older benefited from STN-DBS regardless of short (≤8 years) or longer (>8 years) disease duration. Our results contribute to the debate about DBS selection criteria and timing and call for prospective confirmation in a larger cohort., (© 2017 International Neuromodulation Society.)

Background: Subthalamic nucleus (STN) deep brain stimulation (DBS) improves quality of life (QoL), motor, and non-motor symptoms (NMS) in Parkinson's disease (PD). Few studies have investigated the influence of the location of neurostimulation on NMS., Objective: To investigate the impact of active contact location on NMS in STN-DBS in PD., Methods: In this prospective, open-label, multicenter study including 50 PD patients undergoing bilateral STN-DBS, we collected NMSScale (NMSS), NMSQuestionnaire (NMSQ), Hospital Anxiety and Depression Scale (anxiety/depression, HADS-A/-D), PDQuestionnaire-8 (PDQ-8), Scales for Outcomes in PD-motor examination, motor complications, activities of daily living (ADL), and levodopa equivalent daily dose (LEDD) preoperatively and at 6 months follow-up. Changes were analyzed with Wilcoxon signed-rank/t-test and Bonferroni-correction for multiple comparisons. Although the STN was targeted visually, we employed an atlas-based approach to explore the relationship between active contact locations and DBS outcomes. Based on fused MRI/CT-images, we identified Cartesian coordinates of active contacts with patient-specific Mai-atlas standardization. We computed linear mixed-effects models with x-/y-/z-coordinates as independent, hemispheres as within-subject, and test change scores as dependent variables., Results: NMSS, NMSQ, PDQ-8, motor examination, complications, and LEDD significantly improved at follow-up. Linear mixed-effect models showed that NMS and QoL improvement significantly depended on more medial (HADS-D, NMSS), anterior (HADS-D, NMSQ, PDQ-8), and ventral (HADS-A/-D, NMSS, PDQ-8) neurostimulation. ADL improved more in posterior, LEDD in lateral neurostimulation locations. No relationship was observed for motor examination and complications scores., Conclusions: Our study provides evidence that more anterior, medial, and ventral STN-DBS is significantly related to more beneficial non-motor outcomes., (Copyright © 2018. Published by Elsevier Inc.)

Background: Subthalamic nucleus (STN) deep brain stimulation (DBS) improves quality of life (QoL), motor, and non-motor symptoms (NMS) in advanced Parkinson's disease (PD). However, considerable inter-individual variability has been observed for QoL outcome., Hypothesis: We hypothesized that demographic and preoperative NMS characteristics can predict postoperative QoL outcome., Methods: In this ongoing, prospective, multicenter study (Cologne, Manchester, London) including 88 patients, we collected the following scales preoperatively and on follow-up 6 months postoperatively: PDQuestionnaire-8 (PDQ-8), NMSScale (NMSS), NMSQuestionnaire (NMSQ), Scales for Outcomes in PD (SCOPA)-motor examination, -complications, and -activities of daily living, levodopa equivalent daily dose. We dichotomized patients into "QoL responders"/"non-responders" and screened for factors associated with QoL improvement with (1) Spearman-correlations between baseline test scores and QoL improvement, (2) step-wise linear regressions with baseline test scores as independent and QoL improvement as dependent variables, (3) logistic regressions using aforementioned "responders/non-responders" as dependent variable., Results: All outcomes improved significantly on follow-up. However, approximately 44% of patients were categorized as "QoL non-responders". Spearman-correlations, linear and logistic regression analyses were significant for NMSS and NMSQ but not for SCOPA-motor examination. Post-hoc, we identified specific NMS (flat moods, difficulties experiencing pleasure, pain, bladder voiding) as significant contributors to QoL outcome., Conclusions: Our results provide evidence that QoL improvement after STN-DBS depends on preoperative NMS characteristics. These findings are important in the advising and selection of individuals for DBS therapy. Future studies investigating motor and non-motor PD clusters may enable stratifying QoL outcomes and help predict patients' individual prospects of benefiting from DBS., (Copyright © 2018. Published by Elsevier Inc.)

Background: STN-DBS is well established to improve motor symptoms and quality of life in patients with PD. While non-motor symptoms are crucial for quality of life in these patients, only neuropsychiatric and neuropsychological symptoms have been systematically studied in a longitudinal design so far. However, these are only a part of the non-motor symptoms spectrum., Hypothesis: We hypothesized that STN-DBS is associated with a beneficial effect on a range of non-motor symptoms., Methods: In this multicenter, open, prospective, international study (EuroInf-study, UKCRN10084/DRKS00006735) we investigated non-motor effects of STN-DBS in "real-life" use. We evaluated Non-motor Symptom Scale, and Questionnaire, PD Questionnaire-8, Scales for Outcomes of PD motor examination and complications, and activities of daily living preoperatively and at 6 months follow-up in 60 consecutive patients (35 male, mean age: 61.6 ± 7.8 years, mean disease duration: 10.4 ± 4.2 years)., Results: All outcomes improved significantly at 6 months follow-up (PD Questionaire-8, p = 0.006; activities of daily living, p = 0.012; all others, p < 0.001; Wilcoxon signed-rank, respectively paired t-test; Bonferroni-correction). Post-hoc analyses of Non-motor Symptom Scale domains showed a significant reduction of sleep/fatigue and miscellaneous domains (p ≤ 0.001), perceptual problems/hallucinations (p = 0.036), and urinary (p = 0.018) scores. Effect sizes were "moderate" for Non-motor Symptom Scale, and motor complications, "large" for motor examination, and "small" for other outcomes., Conclusions: This study provides evidence that bilateral STN-DBS improves non-motor burden in patients with PD and opens the door to a more balanced evaluation of DBS outcomes. Further randomized studies are needed to confirm these findings and compare DBS non-motor effects to other invasive therapies of advanced PD., (Copyright © 2015 Elsevier Inc. All rights reserved.)