Using 5-year data from the Parkinson’s Progression Markers Initiative, researchers tracked cognition in drug-naïve patients with Parkinson’s disease (PD; n=676) and healthy controls (n=187). Patients were classified post hoc as developing psychosis (PDP) or not (PDnP) via the Movement Disorders Society Unified Parkinson’s Disease Rating Scale part I hallucinations/psychosis item. Linear mixed-effects models (restricted maximum likelihood) examined trajectories across all repeated cognitive measures, adjusting for age, sex, ethnicity, education, depression, daytime sleepiness, REM sleep behavior disorder, and motor severity. At baseline, PDP and PDnP did not differ cognitively, although PD as a whole scored below controls on most tests.
Across five years, PDP declined more steeply than PDnP in multiple domains—memory (immediate and delayed recall), global cognition (Montreal Cognitive Assessment [MoCA]), visuospatial abilities, semantic fluency, and processing speed—even after full covariate adjustment (eg, MoCA b=−0.206, p<0.001; semantic fluency b=−0.704, p=0.002). The pattern highlights disproportionate vulnerability of semantic aspects of language alongside broader cognitive slowing and visuospatial decline in PD psychosis. Clinically, these results support closer monitoring of semantic fluency and related measures as potential early indicators of emerging psychosis and as targets for intervention aimed at preserving quality of life and delaying dementia risk.
Reference: Pisani S, Gosse L, Aarsland D, et al. Parkinson’s disease psychosis associated with accelerated multidomain cognitive decline. BMJ Ment Health. 2024;27(1):1-10. doi: 10.1136/bmjment-2024-301062.
