All of this research suggests that female hormones might interact with brain chemistry to increase the risk of developing OCD, which could help explain why we see gender differences at different life stages. Since female hormones seem to play a role in OCD, future research should look at the connections between biological sex (male/female based on biology), gender identity (how someone identifies their gender), and OCD symptoms. All the studies in this review asked people to identify their gender on questionnaires. But we're learning more about how gender identity is different from biological sex, so studying the biological factors might help us better understand the differences we're seeing.