Most young children go through a phase when they have a few "habits", for example having to say goodnight in a certain way, or needing a special toy to be with them. Other normal childhood habits might be not stepping on the cracks in the pavement, or touching every other railing. This is a normal; it is not a disorder, does not get in the way of the child's life, and goes away as they grow up.

Older children and adolescents can also have times when they feel very worried, stressed and unhappy. This might become severe enough that a younger person seeks to support, but it does not necessarily mean that you have OCD or any psychiatric disorder.

Young people can also get annoying habits or intrusive thoughts in other illnesses. So it is important that if a young person develops symptoms that are like obsessions and compulsions, they are assessed by a professional who can rule out other problems, and help decide whether this is really OCD.

Doctors know that symptoms similar to obsessions and compulsions can occasionally occur in a range of problems and illnesses, including those listed below:

• Other anxiety disorders
• Depression
• Repetitive behaviours in developmental disorders such as autism
• Learning disability
• Psychotic illnesses such as schizophrenia
• Anorexia nervosa
• Tourette's syndrome