Lesbian, bisexual, or gay individuals (LBGs) have an increased risk for mental health problems compared to heterosexuals, but this association has sparsely been investigated for psychotic disorders. The aim of this study was: (1) to examine whether LBG sexual orientation is more prevalent in individuals with a non-affective psychotic disorder (NAPD) than in people without a psychotic disorder; and if so, (2) to explore possible mediating pathways.

Sexual orientation was assessed in the 6-year follow-up assessment of the Dutch Genetic Risk and Outcome of Psychosis study (GROUP), a case–control study with 1547 participants (582 patients with psychotic disorder, 604 siblings, and 361 controls). Binary logistic regression analyses were used to calculate the risk of patients with a psychotic disorder being LBG, compared to siblings and controls. Perceived discrimination, history of bullying, childhood trauma (CT), and sexual identity disclosure were investigated as potential mediating variables.

The proportion of individuals with LBG orientation was 6.8% in patients (n = 40), 4.3% in siblings (n = 26), and 2.5% in controls (n = 10). The age- and gender-adjusted odds ratio of LBG for patients was 1.57 (95% CI 1.08–2.27; p = 0.019), compared to siblings and controls. Discrimination, bullying, and CT all partially mediated this association.

Adverse social experiences related to sexual minority status may increase the risk for NAPD. Sexual identity, behavior, and difficulties need more attention in everyday clinical practice.