Clinical characteristics in Parkinson's disease patients with cognitive impairment and effects of cognitive impairment on sleep

Abstract

To analyze the clinical characteristics, correlation factors and clinical heterogeneities in Parkinson's disease (PD) patients with cognitive impairment and identify whether cognitive impairment could influence the aspect of sleep. A total of 130 PD outpatients and inpatients of sleep center at our hospital were eligible for participation. According to Montreal cognitive assessment (MOCA), they were divided into cognitive normal group (MOCA ≥ 26) (n = 51) and cognitive impairment group (MOCA < 26) (n = 79). Their clinical characteristics were mainly evaluated by unified Parkinson's disease rating scale (UPDRS) , Hoehn-Yahr (H-Y) stage, Hamilton depression scale (HAMD-24 item) and Epworth sleepiness scale (ESS). And all of them underwent video-polysomnography (PSG). The proportion of cognitive impairment (MOCA < 26) was 60.76%. Compared to those without cognitive impairment, the PD patients with cognitive impairment had significantly higher score of HAMD (10 ± 7 vs 7 ± 4), increased incidence of hallucinations (40.50% vs 19.60%) and REM behavior disorders (RBD) (63.29% vs 39.21%), significantly higher H-Y stage [2.5(2.0-3.0) vs 2.0 (2.0-2.5)] , United Kingdom Parkinson Disease Society (UPDRS) part III (22 ± 10 vs 19 ± 10) and levodopa-equivalent daily dose (LED) (511 ± 302vs 380 ± 272) (all P < 0.05). However, no significant differences existed in the subscores of MOCA between PD patients with different sides of onset and motor subtypes of onset (all P > 0.05). Non-conditional Logistic regression analysis showed that PD duration, score of HAMD and H-Y stage were the major influencing factors of cognition. On PSG, significantly decreased sleep efficiency (57% ± 21% vs 66% ± 17%), higher percentage of non-REM sleep stage 1 (NREMS1) (37% ± 21% vs 27% ± 13%), lower percentage of NREMS2 (40% ± 17% vs 46% ± 13%) and REM sleep (39% ± 28% vs 54% ± 36%) were found for PD patients with cognitive impairment (all P < 0.05). The PD patients with cognitive impairment have more severe disease and partial nonmotor symptoms. And the severity of disease and depression is closely associated with cognitive impairment. Cognitive impairment may also affect sleep to cause decreased sleep efficiency and severe sleep structure disorder.