Changes on brief cognitive instruments over time in Parkinson's disease.

Two hundred and twenty-one subjects with Parkinson's disease (PD) were examined using the Mini-Mental Status Examination (MMSE) and Montreal Cognitive Assessment (MoCA), with a subset of these (n = 98) examined on repeat testing up to 3 years. The MoCA was more sensitive in identifying cognitive deficit, specifically in the domains of visuospatial abilities, language, and memory. In longitudinal study, the MMSE changed significantly over time, particularly in patients with disease duration of >10 years. The MoCA, however, did not change significantly, even when subjects were stratified by age, MMSE score, and disease duration. This suggests that the MoCA may be more sensitive for detecting early cognitive change in PD, but that the MMSE, and not the MoCA, may be better for tracking cognitive decline.