To investigate patterns of change in cognition in early Parkinson disease (PD) and explore determinants of change.

Cognitive impairment in early PD may stabilize, improve, or decline. Studying longitudinal cognitive change can reveal predictive factors associated with better or worse prognosis including the risk of PD dementia.

234 early PD patients (within 5 years of diagnosis) were longitudinally assessed with the Montreal Cognitive Assessment (MoCA) at initial visit and 2-years later (± 6 months) in the University of Maryland Health Outcomes Measurement (HOME) study between 2014-2024. Subgroups were defined by total MoCA scores: normal cognition=26-30, mild cognitive impairment=21-25, and moderate-to-severe impairment=0-20. Cognitive change was defined as: Declined (≤ 2 points), Improved (≥ 2 points), No change (± 1 point).

At initial visit, 52.5% scored in the normal cognitive range (N=123), 36.8% mild impairment (N=86), and 10.7% moderate-to-severe impairment (N=25). At 2-year follow-up, the number in the normal cognition group increased (N=142), while mild impairment decreased (N=64) and moderate-to-severe group remained virtually unchanged (N=28). 41% showed no change in score, 23% improvement, and 36% declined. The majority remained in their same group: 85% of normal cognition, 44% of mild impairment, and 52% of moderate-to-severe impairment. 42% of the baseline mild impairment group improved to normal cognition, and 44% of baseline moderate-to-severe impairment improved to mild impairment. Among those with any baseline cognitive impairment, 23% showed improvement, while 26% had no change and 51% declined.

In early PD, the number of patients scoring in the normal cognitive range increased over a 2-year period. The majority stayed in their subgroups, though a substantial number improved by a higher subgroup, and increased score by two points or more. The capacity for cognitive improvement in early PD is under-recognized. Further analysis will investigate risk factors for improvers vs. decliners.