Cholinergic dysfunction in isolated rapid eye movement sleep behaviour disorder links to impending phenoconversion

Miriam H Terkelsen*, Alex Iranzo*, Mónica Serradell, Andreas M Baun, Morten G Stokholm, Erik Hvid Danielsen, Karen Østergaard, Marit Otto, Kristina B Svendsen, Mette Møller, Erik L Johnsen, Alicia Garrido, Dolores Vilas, Joan Santamaria, Arne Møller, Carles Gaig, David J Brooks, Per Borghammer, Eduardo Tolosa, Nicola Pavese

*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review

Abstract

Background and purpose: Most patients with isolated rapid eye movement sleep behaviour disorder (iRBD) progress to a parkinsonian alpha-synucleinopathy. However, time to phenoconversion shows great variation. The aim of this study was to investigate whether cholinergic and dopaminergic dysfunction in iRBD patients was associated with impending phenoconversion. Methods: Twenty-one polysomnography-confirmed iRBD patients underwent baseline 11C-donepezil and 6-Fluoro-(18F)-l-3,4-dihydroxyphenylalanine (18F-DOPA) positron emission tomography (PET). Potential phenoconversion was monitored for up to 8 years. PET images were analysed according to patients' diagnoses after 3 and 8 years using linear regression. Time-to-event analysis was made with Cox regression, dividing patients into low and high tracer uptake groups. Results: Follow-up was accomplished in 17 patients. Eight patients progressed to either Parkinson's disease (n = 4) or dementia with Lewy bodies (n = 4), while nine remained non-phenoconverters. Compared with non-phenoconverters, 8-year phenoconverters had lower mean 11C-donepezil uptake in the parietal (p = 0.032) and frontal cortex (p = 0.042), whereas mean 11C-donepezil uptake in 3-year phenoconverters was lower in the parietal cortex (p = 0.005), frontal cortex (p = 0.025), thalamus (p = 0.043) and putamen (p = 0.049). Phenoconverters within 3 years and 8 years had lower 18F-DOPA uptake in the putamen (p < 0.001). iRBD patients with low parietal 11C-donepezil uptake had a 13.46 (95% confidence interval 1.42;127.21) times higher rate of phenoconversion compared with those with higher uptake (p = 0.023). iRBD patients with low 18F-DOPA uptake in the most affected putamen were all phenoconverters with higher rate of phenoconversion (p = 0.0002). Conclusions: These findings suggest that cortical cholinergic dysfunction, particularly within the parietal cortex, could be a biomarker candidate for predicting short-term phenoconversion in iRBD patients. This study aligns with previous reports suggesting dopaminergic dysfunction is associated with forthcoming phenoconversion.

Original languageEnglish
Article numbere16503
JournalEuropean Journal of Neurology
Volume31
Issue12
ISSN1351-5101
DOIs
Publication statusPublished - Dec 2024

Keywords

  • REM sleep behavior disorder
  • cholinergic neurons/abnormalities
  • dopaminergic imaging
  • positron emission tomography

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