Parkinson's disease-associated psychosis in a Brazilian sample: prevalence and clinical profile

Psychosis is a frequent and disabling non-motor complication of Parkinson's disease (PD). Reported prevalence varies widely, and data in Brazilian cohorts remain scarce.

To estimate the prevalence of PD-associated psychosis (PDP) in a Brazilian cohort and to describe its sociodemographic and clinical profile.

We conducted a cross-sectional study in a Brazilian movement disorders outpatient clinic between May and December of 2022. Adult patients with idiopathic PD defined by the United Kingdom's Parkinson's Disease Society Brain Bank criteria were consecutively evaluated. Sociodemographic and clinical variables were collected. Psychosis was assessed using the diagnosis criteria proposed by the National Institute of Neurological Disorders and Stroke and the National Institute of Mental Health (NINDS/NIMH) and graded with the Movement Disorders Society's Unified PD Rating Scale (MDS-UPDRS). Cognitive screening was performed using the Mini-Mental State Examination (MMSE), and disease severity was assessed with the modified Hoehn & Yahr scale (mH&Y). Neuropsychiatric symptoms were evaluated with the Neuropsychiatric Inventory Questionnaire (NPI-Q). Descriptive analyses and exploratory univariate comparisons were performed.

In total, 75 patients were included. The median age was 68 years (IQR: 59.5-74.5), and the mean age at PD onset was 56.0 ±  9.8 years. Median disease duration was 10 years (IQR: 6-14.5). Most patients were male (54.7%) and self-identified as Mixed-race (48.6%) or Black (31.1%). According to the mH&Y scale, 82.7% had mild-to-moderate disease. Furthermore, PDP was diagnosed in 18 patients (24%) according to NINDS/NIMH criteria. Minor phenomena and hallucinations were the most frequent psychotic manifestations, each occurring in 72.2% of PDP cases.

In this Brazilian cohort, PDP had a prevalence of 24%. These findings reinforce that psychosis is a frequent non-motor manifestation of PD and highlight the importance of systematic clinical screening in routine care.