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Background: Parkinson's disease (PD) is a progressive neurological disorder that involves a range of motor and non‐motor symptoms. About 66% of individuals with PD report sleep disturbance impacts their quality of life. Sleep disorders may precede the cardinal motor features in PD and can influence motor and non‐motor symptom severity, including cognition. Yet current evidence of this association with objective assessments remains limited. The goal of this pilot study was to evaluate the associations between cognition and overnight polysomnography results in early‐stage PD. Methods: Participants completed neuropsychological assessments and an overnight in‐clinic polysomnography. Associations between polysomnography results and cognitive performance were evaluated using partial correlations controlling for age and education. Results: Twenty participants (mean age 69±8; 25% female) without dementia and with a diagnosis of early‐stage PD (Hoehn and Yahr stage 1‐2) were enrolled (Table 1). Table 2 displays the associations between polysomnography results and cognitive assessments. Greater percentage time in stage N1 sleep and increased duration of wakefulness time after sleep onset (WASO) were associated with poorer phonemic fluency (r = ‐0.626, p =.005 and r = ‐0.512, p =.030, respectively); whereas increased time spent in stage N2 sleep and higher sleep efficiency index were correlated with better phonemic fluency (r = 0.829, p <.001 and r = 0.513, p =.029, respectively). Greater percentage in stage N2 was associated with better verbal learning (Hopkins Verbal Learning Test–Revised (HVLT‐R) Immediate Recall, r = 0.521, p =.027). Higher percent time in REM sleep was correlated with increased basic attention (Digit Span Forward, r = 0.483, p =.042). No associations were found between total sleep time and cognitive performance. Conclusion: While total sleep time was not associated with cognition, higher percent time spent in Stage N2, Stage N3, and REM sleep were associated with better cognitive performance. In contrast, higher percentage of Stage N1 sleep and increased duration of WASO were associated with poorer verbal fluency. The preliminary results highlight the importance of increased time in deeper stages of sleep for cognition in adults with early‐stage PD. Future longitudinal studies will be necessary to evaluate long‐term cognitive trajectories and transition to dementia in association with diminished sleep quality in Parkinson's disease. [ABSTRACT FROM AUTHOR]

Background: Parkinson's disease (PD) is a neurodegenerative disorder affecting 1% of the global population. While the core clinical symptoms of PD are bradykinesia, rigidity, and tremor, it is also often accompanied by non‐motor symptoms that reduce quality of life and increase health care costs. Of the non‐motor symptoms in PD, hyposmia is one of the most prevalent and often precedes clinical diagnosis by several years. In addition, hyposmia has been associated with accelerated disease progression. As individuals with PD are at elevated risk for dementia, the goal of this pilot study was to objectively evaluate the association between smell sensitivity and cognition in early‐stage PD. Method: Participants with a clinical diagnosis of PD completed cognitive assessments of verbal and visual learning and memory, processing speed, attention, and executive function. Smell sensitivity was assessed using the University of Pennsylvania Smell Identification Test (UPSIT). Associations between cognitive performance and smell sensitivity were evaluated using partial correlations adjusting for age and education. Result: Nineteen participants (mean age 69.4+7.9, 25% female) with early‐stage Parkinson's disease (Hoehn and Yahr stage 1‐2) and free of dementia completed the UPSIT and cognitive assessments (see table 1 for sample characteristics). The average UPSIT score was 5.84+2.12 points and ranged from 2 to 10. Diminished olfactory sensitivity, assessed by the total correct score on the UPSIT, was associated with poorer visual learning (Brief Visual Memory Test Revised (BVMT‐R) immediate recall: r = 0.564, p = 0.18, Figure 1) and memory (BVMT‐R delayed recall: r = 0.610, p = 0.009, Figure 2). Conclusion: In the early‐stages of PD, diminished smell sensitivity was associated with poorer visual learning and memory, domains preferentially affected by the disease. The findings suggest that olfactory dysfunction may be a biomarker of cognitive decline. Larger, longitudinal studies will be important for evaluating the utility of olfactory function as a predictor of dementia risk in PD. [ABSTRACT FROM AUTHOR]