Obsessive Compulsive Disorder - OCD - is a psychiatric disorder that occurs in childhood, early adolescence, or in adulthood, most often following a traumatic event, or during depression. Environmental, biological and social factors are involved. There are two types of symptoms: on the one hand, obsessions, characterised by intrusive and repetitive thoughts, images or irrational impulses that are difficult to control, are against the person's will and are accompanied by anxiety; on the other hand there are compulsions which may be body movements or repetitive rituals. These compulsions are seen as an answer, a defence or an attempt to reduce the fear, distress and discomfort caused by obsessions. Compulsions consume a lot of time (up to several hours) and have a heavy impact on the daily life of people affected by OCD because, once the repetitive are started they cannot be interrupted. The person is perfectly aware of the absurdity of this behaviour but will not be able to control it without specialist help. Common obsessions are fear of germs, dirt, fear of hurting others, perverse images or thoughts related to sexuality, fear of throwing, order or alignment of objects. The most common compulsions consist of constantly washing or cleaning, checking, needing to touch, mentally counting, checking doors, clothes, gas, lights, and hoarding objects.