0788 Patient-Bedpartner Subjective Sleep Mismatch in Isolated REM Sleep Behavior Disorder Is Associated with Cognitive Decline and Cortical Thinning

Abstract Introduction Patients with Parkinson’s disease commonly underreport sleep symptoms, but the extent to which such mismatch may be present in people with isolated RBD (iRBD) is unknown. We evaluated how the patient–bedpartner (PT–BP) mismatch in night-time and daytime sleep complaints relates to cognition, apathy, dopaminergic degeneration, and cortical structure in iRBD. Methods We retrospectively analyzed 425 iRBD participants (2018–2025) from the North American Prodromal Synucleinopathy (NAPS) Consortium with clinicodemographic data, dopamine transporter (DAT) imaging, and magnetic resonance imaging. Using Scales for Outcomes in Parkinson’s Disease (SCOPA)-Sleep, PT–BP mismatch was classified into overestimator (PT>BP), concordant (PT=BP), and underestimator (PT< BP) groups, separately for complaints during night and day. Outcomes included cognition (CDR-Sum of Boxes [CDR-SB], CDR-global, and individual subdomain tests), pareidolia, apathy, subregional DAT uptake, and cortical thickness. Group differences were tested with analysis of covariance adjusting for age, sex, disease duration, education, clinician-rated OSA treatment inadequacy, and the corresponding patient-reported SCOPA-Sleep domain (night or day), and estimated total intracranial volume for cortical thickness; pairwise tests used Bonferroni correction. Results The PT–BP mismatch was common (night – overestimator 127/425, 29.9% and underestimator 116/425, 27.3%; day – overestimator 77/425, 18.1% and underestimator 134/425, 31.5%). For night-time mismatch, underestimators showed lower CDR-SB and lower CDR-global than overestimators. In addition, underestimators exhibited more illusory responses, fewer correct noise rejections, and fewer total correct responses than overestimator and concordant groups. For daytime mismatch, CDR-SB was lower in underestimators versus overestimators; CDR-global was lower in underestimators and concordant participants versus overestimators. No significant associations were found for apathy. Subregional DAT uptake did not differ by mismatch group. Cortical thickness analyses revealed thinner right transverse gyrus in underestimator and concordant groups compared to the overestimator group and thinner left superior temporal gyrus in underestimator group compared to overestimator group, for night-time mismatch only. Conclusion The PT–BP subjective sleep mismatch can be used as a clinical marker associated with overall cognitive decline and cortical thinning in auditory and language processing areas, which may underlie impairment in perceptual interpretation and hallucination proneness. Further research is warranted to seek longitudinal change and phenoconversion in mismatch groups. Support (if any) #U19-AG071754 (NAPS Consortium)