Assessment of cognitive impairment in patients with Parkinson's disease: prevalence and risk factors

Background: Although Parkinson's disease (PD) is clinically characterized by motor symptoms, cognitive impairment is one of the most disabling non-motor symptoms. Despite it attracting increasing attention worldwide, less is known about its prevalence in the Chinese population. The objective of this study was to assess cognitive impairment and related risk factors in Chinese PD patients. Methods: We collected the demographic, diagnostic, and treatment information of 901 PD patients from 42 centers throughout the People's Republic of China, then administered a battery of neuropsychological tests, to assess motor, cognitive, and neuropsychiatric symptoms. Results: Overall, 193 of 901 (21.4%) PD patients met the criteria for dementia (PD-D), and 206 (22.8%) met the criteria for mild cognitive impairment (PD-MCI). Visuospatial dysfunction and attention/executive impairment predominated. Increased severity of cognitive impairment was associated with greater motor impairment. Patients with psychiatric symptoms, such as depression and hallucinations, were more likely to have dementia. Potentially, the younger-aged and more educated are shown less cognitive impairment, but age at onset, and levodopa equivalent dose, were not associated with the presence of cognitive dysfunction. Conclusion: The prevalence and profile of cognitive impairment in Chinese PD patients, as well as the risk factors, are similar as those reported for other races, but the frequency of nonamnestic cognitive domains differs.