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Background: Recently, many studies have investigated the association between orexin A and Alzheimer's disease (AD). However, it remains to be determined whether the observed changes in orexin A levels are associated with pathological changes underlying AD, or cognitive function. In particular, a direct association between cerebrospinal fluid (CSF) orexin A levels and cognitive function has not been reported to date.Objective: The aim of this study was to identify whether there is a direct association between the orexinergic system and cognitive function in AD.Methods: For this study, we included 22 patients with AD and 25 control subjects who underwent general physical, neurological, and psychiatric examinations, neuroimaging, and CSF collection by lumbar puncture were enrolled. Correlations between CSF orexin A levels and CSF AD biomarker levels (i.e., levels of phosphorylated tau [p-tau], Aβ42, and Aβ42/Aβ40) were assessed to confirm the results of previous studies. Moreover, the correlation between CSF orexin A levels and Mini-Mental State Examination (MMSE) and Japanese version of the Montreal Cognitive Assessment (MoCA-J) scores were analyzed.Results: There was a significant positive correlation between CSF orexin-A levels and cognitive function (MMSE scores: r = 0.591, p = 0.04, MoCA score: r = 0.571, p = 0.006) in AD patients.Conclusion: This is the first study to our knowledge demonstrating an association between cognitive function and CSF orexin A levels in AD. Our results suggest the possibility that orexinergic system overexpression is not always a negative factor for cognitive function In AD. [ABSTRACT FROM AUTHOR]

Purpose: Myotonic dystrophy type 1 (DM1) is often characterized by excessive daytime sleepiness (EDS) and sleep-onset rapid eye movement periods caused by muscleblind-like protein 2. The EDS tends to persist even after treatment of sleep apnea. We measured the cerebrospinal fluid (CSF) orexin levels in DM1 patients with EDS and compared the clinical characteristics with narcolepsy type 1 and idiopathic hypersomnia (IHS) patients. Patients and methods: We measured the CSF orexin levels in 17 DM1 patients with EDS and evaluated subjective sleepiness using the Epworth Sleepiness Scale (ESS), objective sleepiness using mean sleep latency (MSL), and sleep apnea using apnea-hypopnea index (AHI). We compared the ESS scores and MSL between decreased (≤200 pg/mL) and normal (<200 pg/mL) CSF orexin group in DM1 patients. Furthermore, we compared the CSF orexin levels, ESS scores, MSL, and AHI among patients with DM1, narcolepsy type 1 (n=46), and IHS (n=30). Results: Seven DM1 patients showed decreased CSF orexin levels. There were significant differences in the ESS scores and MSL between decreased and normal CSF orexin groups in DM1 patients. The ESS scores showed no significant difference among patients with DM1, narcolepsy type 1, and IHS. The MSL in DM1 and IHS patients were significantly higher than narcolepsy type 1 patients (p=0.01, p<0.001). The AHI in DM1 patients was significantly higher than narcolepsy type 1 patients (p=0.042) and was insignificantly different from IHS patients. The CSF orexin levels in DM1 patients were significantly lower than IHS patients and higher than narcolepsy type 1 patients (p< 0.001, p<0.001). Conclusion: The CSF orexin levels of DM1 patients moderately decreased compared to those of IHS patients as the control group. However, the EDS of DM1 patients may not be explained by only orexin deficiency. [ABSTRACT FROM AUTHOR]

Public concern has been growing over severe adverse events caused by human papillomavirus (HPV) vaccination. Some patients also exhibited sleep disorders. We investigated their symptoms, clinical examinations and cerebrospinal fluid orexin (hypocretin) levels. The subjects were 6 patients with hypersomnolence after HPV vaccination. Since all of them had normal orexin levels, hypersomnolence was not caused by orexin deficiency. Although each case did not meet the diagnostic criteria of narcolepsy type 2 and idiopathic hypersomnia adequately, one case had frequent multiple SOREMPs and the other had shortened sleep latency. They might be affected with symptoms of hypersomnolence disorders after their vaccination. [ABSTRACT FROM AUTHOR]