Objective: To ascertain the utility of the MSQ in predicting final autopsy diagnosis of an alpha-synuleinopathy.

Background: Idiopathic REM sleep behavior disorder (iRBD) is a strong clinical predictor of synucleinopathy risk. Definite diagnosis requires a polysomnogram (PSG), but dream enactment behavior (DEB) noted by an informant on the Mayo Sleep Questionnaire (MSQ) has previously shown 100% sensitivity and 95% specificity for identification of PSG confirmed iRBD patients.

Methods: Since 2007, 206 subjects in the Arizona Study of Aging and Neurodegenerative Disorders had an informant available to complete the MSQ and also completed clinical examinations (movement and cognitive) and then an autopsy as previously described. A final clinicopathological diagnosis was assigned to each case according to consensus criteria based upon all clinical and neuropathological data.

Results: Of the 206 subjects with informant MSQ data available, 59 (28.6%) were female, mean age at death was 84 (SD 8). Most common final diagnoses (regardless of DEB status) were Alzheimer disease (AD) in 95 (46%), Parkinson’s disease (PD) in 53 (25.7%), and dementia with Lewy bodies (DLB) in 20 (9.7%). Mixed AD/Lewy body (LB) pathology was common. Pure AD pathology was present in only 23/95 (24.2%) AD cases and pure DLB pathology in only 1/20 (5.0%) DLB cases. Of PD cases, 26/53 (49%) had pure PD. Synucleinopathy {DLB, PD, or incidental Lewy body disease(ILBD)} was diagnosed in 50/63 (79%) cases with DEB and 61/143 (43%) without DEB (p <0.001); sensitivity 45%, specificity 86%, positive predictive value 79%, negative predictive value 57%. DEB was present in 28/95 (29.5%) of all AD, 5/23 (21.7%) pure AD, 7/20 (35.0%) of all DLB, 1/1 pure DLB, 35/63 PD, 18/26 pure PD, 0/11 ILBD, 2/21 vascular dementia, 5/16 progressive supranuclear palsy, and 1/3 corticobasal degeneration cases.

Conclusions: The informant completed MSQ appears useful for identification of individuals who will have a synucleinopathy neuropathologically. Due to our study population, these data are limited by a low number of atypical parkinsonism cases, but suggest that DEB can be seen in a relatively large fraction of AD cases without co-existing synuclein pathology. A prospective population based study of PSG confirmed iRBD cases being followed to autopsy is needed to confirm the accuracy of an RBD diagnosis as a predictor of underlying synuclein pathology.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/utility-of-the-mayo-sleep-questionnaire-in-predicting-final-autopsy-diagnosis-of-alpha-synucleinopathy/