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

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).

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

We conducted a 3-year, prospective, observational study of individuals with PD minor phenomena with biannual study visits. The presence of psychosis was ascertained using the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part I Hallucinations and Psychosis item and the enhanced Scale for the Assessment of Positive Symptoms in PD (eSAPS-PD). The primary outcome variable was the time from baseline to the development of psychosis. Proportional hazards regression models were applied to examine potential risk factors for the development of psychosis.

We enrolled 38 individuals with PD minor phenomena and included 34 in the primary analysis (47% female with mean standard deviation [SD]), with age 70.3 (7.9) years and mean (SD) time from PD diagnosis 7.5 (5.9) years). Twenty-four (71%) of the 34 developed psychosis during follow-up. None of the examined demographic or clinical variables were associated with the time to development of psychosis.

Over a 3-year period, there was a high cumulative probability of psychosis among individuals with PD minor phenomena in this single-center prospective study.