Using the Montreal Cognitive Assessment Scale to screen for dementia in Chinese patients with Parkinson's Disease

BACKGROUND: Dementia is one of the most distressing and burdensome health problems associated with Parkinson's Disease (PD). The Montreal Cognitive Assessment scale (MoCA) is widely used to screen for dementia in PD patients, but the appropriate diagnostic cutoff score when used with Chinese PD patients is not known. AIM: Determine a diagnostic cutoff value of the Chinese version of the MoCA (MoCA-C) for Chinese PD patients and describe the characteristics of PD patients screened positive for dementia using the MoCA-C. METHODS: The presence of dementia in 616 PD patients and 85 community controls was determined using the Movement Disorder Society Task Force criteria (the gold standard diagnosis). We administered the MoCA-C to these individuals and used a receiver operating characteristic (ROC) curve to identify the cutoff score of the MoCA-C that most efficiently identified dementia in both PD patients and community controls. Demographic and clinical characteristics of PD patients who were screened positive or negative for dementia using the MoCA-C were compared. RESULTS: A MoCA-C score of 23 was the optimal cutoff score for dementia in both patients and controls. Using this cutoff score, the sensitivity and specificity of the MoCA-C in PD patients were 0.70 and 0.77, respectively; the positive and negative predictive values were 0.59 and 0.85, respectively; and the overall concordance (kappa [95% confidence interval]) was 0.45 (0.39-0.52). The corresponding kappa value (concordance) in community controls was only 0.25 (0.05-0.45). Compared to PD patients who screened negative for dementia, those who screened positive for dementia were significantly impaired in all cognitive domains, including visuospatial and executive functioning, naming, attention, language, abstraction, delayed recall and orientation (all p<0.001). Among the PD patients, screening positive for dementia was independently associated with old age, low educational attainment, female gender and more severe motor impairment. CONCLUSIONS: The commonly recommended cutoff screening score for dementia of 26 on the MoCA it too high for PD patients in China; a cutoff score of 23 is more appropriate. Potential risk factors for dementia in Chinese PD patients include older age, less education, and more severe motor symptoms of PD.