Reader Response: Cognitive-Driven Activities of Daily Living Impairment as a Predictor for Dementia in Parkinson Disease: A Longitudinal Cohort Study

The article by Becker et al.(1) presents highly relevant longitudinal data and poses the question of how to monitor cognition and select participants for clinical trials. For this, it suggests the comprehensive Functional Activities Questionnaire (FAQ) as a tool.(2) In an attempt to explore whether cognition can be assessed longitudinally with less time-consuming bedside tests, we evaluated existing data from the EPIPARK study, which offers longitudinal data of 655 cases with Parkinson disease and 622 controls.(3) Specifically, we calculated the correlation between the frequently used Montreal Cognitive Assessment (MoCA) and the Unified Parkinson Disease Rating Scale (UPDRS) question on cognition (r = -0.319, 95% CI -0.368 to -0.268).(4) This moderate correlation is not sufficient to replace the MoCA with this single UPDRS question. However, the MoCA sum score itself correlates across time points 1 and 2 after a year (r = 0.705 [95% CI 0.649-0.754]) and time point 1 to present (12 years of follow-up; r = 0.522 [95% CI 0.411-0.618]). In light of this data, it would be interesting to learn whether the MoCA and the cognition section of the FAQ correlate in the study conducted by Becker et al. and whether the 2 could be used interchangeably to facilitate broad screening of patients for the development of Parkinson disease dementia.