There is no single established cause of OCD. However, researchers believe the disorder may be affected by brain chemistry, genes, and even infections. Current research is examining the role of chemical messengers called serotonin, dopamine, and glutamate in the brain and is looking at how different parts of the brain communicate with each other. Researchers are also looking into whether the immune system may be involved in causing OCD.
People with OCD may experience symptoms of the disorder after a stressful life event, such as a death in the family or job loss. However, it is thought that OCD is only worsened by stress, and not caused by stress.