Causes of OCD
Up to this day, there is no clear answer as to what causes OCD. Research data indicate that its development is influenced by a combination of genetic and environmental factors. However, it is important to note that although the causes of OCD have not been fully clarified, the evidence-based treatments namely Exposure and Response Prevention (ERP) and pharmacotherapy have a fairly significant success rate, reaching 60–70%.
Genetic Factors
Studies on twins and families suggest that individuals who have a first-degree relative with OCD are about four times more likely to develop the disorder compared to those without a first-degree relative with OCD (Perez et al., 2013; Harrison et al., 2020). Although genetic factors are important, no single "OCD gene" has been identified.
At the same time, other scientific findings indicate that in OCD there is impaired communication between the anterior part of the brain and deeper brain structures. According to Dr. Carol Mathews, Director of the Center for OCD, Anxiety and Related Disorders (COARD), and the Interim Director for the UF Health Center for Neurodevelopment for Department (CAN) of Psychiatry at the University of Florida who recently co-led a genetic study:
""Over time, we've come to realize that OCD is not a disease of a single gene or specific brain region, but rather it's a disease of circuits and hundreds of genes, which together contribute to the development ofthe disorder." (UF Health, 2025 ).
Selective serotonin reuptake inhibitors (SSRIs) are used in the treatment of OCD. However, the view that OCD is solely due to a dysfunction of this neurotransmitter or of others is now considered outdated and overly simplistic (International OCD Foundation).
Environmental Factors
Beyond genetic influences, environmental factors play a significant role in the onset and course of OCD. Traumatic or stressful life events, such as severe illness, loss, or abuse, may contribute to the manifestation of the disorder's symptoms.
Sources:
Harrison, P., Cowen, P., Burns, T., & Fazel, M. (Επιμ.). (2020). Oxford Ψυχιατρική – Βασικές αρχές (7η έκδ., ελληνική έκδοση, Ν. Κ. Στεφανής, Επιμ.). Broken Hill Publishers.
International OCD Foundation. (n.d.). What causes OCD? Retrieved September 6, 2025, from https://iocdf.org/about-ocd/
Strom, N. I., Gerring, Z. F., Galimberti, M., Yu, D., Halvorsen, M. W., Abdellaoui, A., Rodriguez-Fontenla, C., Sealock, J. M., Bigdeli, T., Coleman, J. R., Mahjani, B., Thorp, J. G., Bey, K., Burton, C. L., Luykx, J. J., Zai, G., Alemany, S., Andre, C., Askland, K. D., … Mattheisen, M. (2025). Genome-wide analyses identify 30 loci associated with obsessive-compulsive disorder. Nature Genetics, 57(6), 1389–1401. https://doi.org/10.1038/s41588-025-02189-z
UF Health. (2025, February 28). Worldwide OCD genetics study offers clues for higher risk. University of Florida Health. https://ufhealth.org/news/