Introduction
Population aging in Brazil has important implications for public health, including an increased prevalence of mental disorders. Few Brazilian studies have assessed these conditions in community-dwelling older adults using DSM-5 criteria.

Objective
To determine the prevalence of mental disorders in older adults according to DSM-5 diagnostic criteria.

Methods
A cross-sectional study was conducted with 267 older adults living in the catchment area of a Primary Health Care Unit in São Paulo State. Structured clinical evaluations based on DSM-5 were conducted by trained psychiatrists. Frequencies were calculated, and logistic regression analyses examined associations with sex, age, and education. Results: The prevalence of any current mental disorder was 74.2%, with 46.8% presenting two or more diagnoses. The most frequent disorders were generalized anxiety disorder (17.6%), depressive disorders (13.5%), and neurocognitive disorders (34.0%). Female sex was associated with greater odds of generalized anxiety disorder (OR=2.3; 95% CI: 1.12–4.74; p=0.032) and marginally with major depression (OR=2.02; 95% CI: 0.93–4.42; p=0.077). Older age was associated with both mild (OR=1.06; 95% CI: 1.02–1.11; p=0.005) and major neurocognitive disorders (OR=1.06; 95% CI: 1.00–1.12; p=0.037), whereas lower education was associated with major neurocognitive disorder (OR=0.75; 95% CI: 0.59–0.95; p=0.019).

Conclusions
The prevalence of mental disorders in community-dwelling older adults was high, particularly for anxiety, depression, and neurocognitive disorders. These findings highlight the need for screening and mental health strategies targeting this population, especially in primary care settings.