Objective: The purpose of this study was to clarify the relationship between sleep disorders and cognitive function in PD by overnight electroencephalogram (EEG) and sleep apnea tests.

Background: Factors for cognitive decline in PD include impaired ADL, sociality, and the spreading of PD pathology. REM sleep behavior disorders: RBD is a well-known sleep disorder in PD, but there are few studies on sleep quality. We started studies focusing on the relationship between abnormalities in sleep construction and cognitive impairment in PD.

Method: The subjects were 30 PD patients who agreed to this survey. The mean duration illness:15.2 years, the mean age : 68.7±6.8 years. ADLs: almost self-reliant. They checked overnight-EEG , sleep apnea test, intelligence tests. The tests performed multiple times, interval between tests was 2 years or more, and statistical processing (non-parametric test) was performed on the results. Exclusion criteria are them. 1) over 85 years old, 2)MMSE: Mini-mental State Examination <25, 3)Duration of illness20<,5) advanced physical disability on language.

Results: Based on the results of the overnight EEG, the sleep patterns of PD patients were divided into two groups by 1^st test. Group1: Only light sleep in stages 1-2 : 17 patients. Light sleep with sleep fragmentation :8/17 patients. Group2: Observed deep sleep :13 patients. 1) Deep sleep with REM sleep: 12/13 patients, 2) observed REM sleep without atonia (RWA): 5 /12 patients. Frequency of sleep apnea was same as normal aged matched people. Results for the relation to cognitive function(IQ; WAIS IV) and sleep analysis were bellowed.1) IQ points of group1; 95.2±14.2 (the 1^st time) showed decline to 89.1±17.5 (the 2^nd time) (P<0.05). 2) The average IQ points of group2;100.4±13.4 (the 1^st time) and 98.0±13.2 for the second time (P=0.35). 3) The average IQ points of group2-1) was 96.8±15.6 (the 1^st time) and 93.1±18.6 (the 2^nd time) (P=0.23). 4) The average IQ points of group2-2) was 97±11.8 (the 1^st time ) and 90.9±13.0 (the 2^nd time) (P=0.12).

Conclusion: In PD patients who had deep sleep w/wo REM sleep, there was no significant change in cognitive function compared to the 1^st and 2^nd examination. However, there was a significant decrease in IQ in PD patients who had only light sleep. Maintaining sleep construction and REM sleep are important for keeping cognitive function in PD. We plan to accumulate more cases in the future.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/poor-sleep-quality-is-one-of-the-causes-of-cognitive-decline-in-parkinsons-disease-pd-1/