' OCD ' (Obsessive Compulsive Disorders ) are symptoms, like for example : Verify excessively if the door is locked, clean the hands throughout the day, rituals, etc....
The causes of the OCD are unconscoious for people who have them, that is why they don't know why they act excessively and so, can't control them.
People who have OCD have a generalized guilt, but they don't know it, since it's unconscious. Ex with ' mania verification ' : they are under the impression that ' someone ' checks everything they do and they feel constantly guilty. For avoid that / to be blamed, they excessively verify the door. All these feelings still happen in the unconscious of people and create much anxiety / anguish.
For fix OCD the best is to start a Psychoanalysis, for find the deep causes. It's a long work on oneself, but it worth it since once they are found, the symptoms stop. As the patient found and understood them, by reviving the old circumstances that generated them in the past / often childhood.