Obsessive compulsive disorder (OCD) are a cluster of symptoms based around obsessions (intrusive thoughts and fears that cause anxiety) and compulsions (rituals that are carried out in an attempt to alleviate the anxiety of the obsessions).

Common obsessions include:

• fear of forgetting to perform important tasks - e.g. turning off appliances or locking doors

• fear of being contaminated by things that are unclean - e.g. dirty cutlery, food, keys, door handles and bathrooms

• fear of not being able to do things in an exact or orderly way

• fear of becoming sick, having an accident or dying

• intrusive thoughts about violence, accidents or sex.