Long-Term Outcomes in a Parkinson's Disease Minor Phenomena Cohort.

Background: Minor phenomena, including illusions, feeling of presence, and passage hallucinations, are common in Parkinson's disease (PD) and may be a risk factor for the development of psychosis (hallucinations and delusions).

Objectives: The objective of this study was to determine the 3-year cumulative probability of developing psychosis among individuals with PD minor phenomena.

Methods: We conducted a 3-year, prospective, observational study of individuals with PD minor phenomena with biannual study visits.