Clinical analysis of cognitive function in patients with Parkinson’s disease

Objective To explore the clinical characteristics of cognitive function in patients with Parkinson’s disease (PD) and its correlation with the condition. Methods A total of 96 patients with idiopathic PD, admitted to Department of Neurology and Geriatrics of Peking University Shenzhen Hospital from February 2017 to September 2019, were included. The Montreal cognitive assessment (MoCA) scale was used to evaluate the cognitive function of PD patients. All patients were assessed with Hoehn-Yahr (H-Y) stage during the off-period. Using the H-Y stage of 2 as a boundary, it was divided into early stage group (H-Y 2 and below) and middle to late stage group (above H-Y 2). The cognitive scores were compared between the two groups. Logistic regression analysis was used to screen for protective factors or risk factors for cognitive dysfunction, and correlation analysis was used to study the linear correlation between cognitive scores and H-Y stages. Results There were 51 patients in the early stage group and 45 in the middle to late stage group. The H-Y stage was mainly concentrated in stages 1-3, accounting for 90.63% of the total population. The prevalence of cognitive impairment detected by the MoCA scale was 67.71%, and the incidence of PD cognitive impairment in middle to late stage group was higher than the early stage group (77.8% vs 58.8%, P=0.047). There was no difference in age, age of onset, gender, clinical onset symptoms, and years of education between the two groups; while the course of disease showed different, the median course of disease in the middle to late stage group was longer than that of the early stage group (8 years vs 4 years, P<0.001). The total score of the MoCA scale was different (P=0.007), the median total score was 25 points and 21 points, showing differences in visuospatial and executive function, naming, alertness, and abstraction. Logistic regression analysis found that years of education was a protective factor of cognitive function (P<0.001, OR=0.703), and H-Y stage would be a risk factor (P=0.035, OR=1.829). Correlation analysis found that there was a positive correlation between cognitive score and years of education (r=0.610, P<0.001), and a negative correlation between cognitive score and the adjusted H-Y stages(r=-0.320, P=0.002). Conclusion Cognitive dysfunction has a high incidence in PD, mainly showed in visuospatial and executive function, alertness. No cognitive differences caused by age, gender, and clinical onset symptoms were found. Years of education cannot be changed, and it is a protective factor for cognitive function. H-Y stage is related to the risk of cognitive impairment in the future. Key words: Parkinson’s disease; Cognitive impairment; Hoehn-Yahr stage