what causes ocd

Obsessive-compulsive disorder (OCD) can be caused by a combination of factors, including genetics, differences in the brain, and life events. Research suggests that OCD may be more likely to develop if a family member has it, indicating a possible genetic component. Additionally, some people with OCD have areas of unusually high activity in their brain or low levels of a chemical called serotonin. OCD may also be more common in people who have been bullied, abused, or neglected, and it sometimes starts after an important life event, such as childbirth or a bereavement