[Relationship between emotional apathy and motor symptoms, sleep and cognitive function in patients with early...

Objective: To study the relationship between emotional apathy and motor symptoms, sleep, and cognitive function in patients with early Parkinson's disease (PD). Methods: One hundred and twenty-nine early PD patients who were treated in the Second Affiliated Hospital of Soochow University from June to October 2020 were included, including 82 male and 47 female patients. The emotional apathy was assessed by modified apathy rating scale (MAES). The above 129 patients were divided into 67 patients in the PD with emotional apathy group (MAES>14 points) and 62 patients in the PD without emotional apathy group (MAES≤ 14 points). Age, gender, course of disease and levodopa equivalent dose were also collected. Hoehn-Yahr stage and unified Parkinson's disease rating scale PartⅢ(UPDRS-Ⅲ), Pittsburgh Sleep Quality Index (PSQI), polysomnography, and Montreal Cognitive Assessment Scale (MoCA) were used to evaluate the motor symptoms, sleep and cognitive functions of patients with early PD, and the clinical characteristics of patients with early PD with apathywere determined. Results: Compared with PD patients without apathy, those with apathy had longer disease duration [M(Q₁,Q₃)][5.0 (3.0, 7.0) years vs 3.0 (2.0, 5.0) years, P=0.006] and severer motor symptoms [20.0 (10.0, 28.0) vs 14.0 (8.5, 23.0), P=0.047]. There was no significant difference in PSQI score between the two groups. Among the 33 patients who completed polysomnography, compared with PD patients without apathy (n=16), those with apathy (n=17) had a longer rapid eye movement (REM) sleep latency [150 (124, 184) min vs 87 (57, 133) min, P=0.035)] and more frequent periodic limb movements in the REM phase(P=0.042).The REM sleep ratio (r=0.373, P=0.042), apnea-hypopena index (AHI)(r=0.374, P=0.046) and oxygen deficit index (r=0.409, P=0.025) were positively correlated with the degree of apathy in PD patients. PD patients with apathy had relatively poorer performance in cognition assessment than those without apathy and total MoCA score was inversely correlated with the degree of apathy (r=-0.231, P=0.017). Conclusion: Early PD patients with apathy have objective sleep disorders dominated by REM sleep disorders, which can have a negative impact on cognitive function.