Sex and gender differences in OCD: A scoping review

This scoping review examines sex and gender differences in obsessive-compulsive disorder (OCD) to generate hypotheses about sources of heterogeneity. A PubMed search (2009-2025) using terms related to sex, gender, and OCD identified 7,497 records. Records were screened by two reviewers, and 1,446 articles were assessed at the full-text level by four co-authors. Of these, 855 studies were included: 61 meta-analyses, 13 systematic reviews, 39 narrative reviews, and 742 original reports. Original studies were grouped by focus--symptoms (96), epidemiology (217), comorbidities (187), human genetics (89), neurocognitive and neurobiological functioning (56), treatment (66), animal models (55)--and evaluated using CASP checklists. Across domains, sex- and gender-related patterns in OCD have been reported, but findings remain fragmented and rarely synthesized. Methodological limitations include inconsistent assessment of sex and gender, variability in symptom measurement, limited consideration of menstrual and reproductive factors, and few genome-wide or whole-brain imaging studies. Biases may also arise from gender differences in insight, help-seeking behavior, and comorbidity. Synthesizing these findings, we hypothesize that two OCD subtypes may contribute to observed sex and gender patterns. One subtype (OCD-I) is characterized by earlier onset and stronger familial or neurodevelopmental loading and shows a male preponderance that may reflect a female protective effect. A second subtype (OCD-II) is more often stress-precipitated, emerges later, and may be more common in women due to greater exposure to interpersonal, reproductive, and traumatic stressors rather than greater innate susceptibility. Appreciating sex and gender effects may clarify OCD heterogeneity and inform research, prevention, and treatment.