What is Obsessive-compulsive disorder?

Please note this section is currently under review.

Obsessive-compulsive disorder (OCD) is an anxiety disorder in which the person most commonly experiences frequent, distressing, recurrent thoughts, known as obsessions. These thoughts result in significant distress and anxiety which the person learns to cope with by developing actions, known as compulsions or rituals, which they feel compelled to perform in order to reduce the anxiety associated with the obsession.

Obsessions can take the form of:


  • Thoughts: for example, the idea or belief that the you have been contaminated by something, or that you have harmed or are going to harm someone
  • Images: for example, mental images of a violent or sexual nature which are distressing and intrusive
  • Other forms of obsessions can take the form of obsessive impulses or obsessive doubt about something.

Obsessions are always distressing and never pleasurable. They can seem to be completely senseless to the person experiencing them such that people can fear that they are losing their mind or going crazy. Attempts to block out obsessions or not to think about them are invariably unsuccessful and they lead to severe anxiety.

In most people, they learn to cope or manage this anxiety by developing actions or behaviours which are known as compulsions.

Examples include:


  • Washing one’s hands very frequently in response to the obsessive thought that one is contaminated by germs.
  • Checking behaviours, e.g. repeatedly checking that home appliances are switched off or that windows/doors are locked in response to the obsession of doubt.
  • Avoidance behaviours – avoiding anything that has to do with a particular obsession, e.g. avoiding the use of knives or avoiding being alone with a particular person.
  • Reassurance – frequently asking others to reassure you that everything is alright.
  • Feeling the need to think or do something which will prevent the obsessive idea from coming true, e.g. some people feel the need to count to a certain number, or to say a certain word in response to experiencing an obsessive thought or image.

These compulsions can take up a considerable amount of time and prevent people from getting on with their normal daily life such that they can become very disabled by them.

OCD will affect about 2% of the population at some stage during their lives and most commonly begins to affect people during their teens or early adulthood. It can be many years before people seek help.

Like most mental illnesses, there is not a single cause for OCD. In most it develops due to a combination of several factors acting together.

OCD has been linked to an imbalance in the chemical serotonin,  which helps brain cells to communicate effectively. Stressful experiences are also commonly associated with the onset of OCD symptoms. In addition, it has been shown to have a genetic component, such that it can sometimes be inherited and run in families. Finally, certain personality types can be more vulnerable to developing OCD at some point, e.g. people who are perfectionists or very conscientious are more at risk, especially at times of stress or major change in their lives.

OCD is best treated through a combination of medication and psychotherapy.

Cognitive-behaviour therapy: The goal of cognitive-behaviour therapy is to teach people with OCD to confront their fears and reduce anxiety without performing ritual behaviours. It seeks to break the reinforcing cycle between obsessions and compulsions and also focuses on reducing the exaggerated or faulty thinking patterns that often occur in people with OCD.

Medication: A group of drugs called selective serotonin reuptake inhibitors (SSRIs) work by increasing and sustaining the levels of serotonin in the brain, thus improving the movement of electrical signals from neuron to neuron. It is important to be patient when taking these medications, as it can be several weeks or even months before an improvement occurs. Other medications can also be effective for those who do not respond to their initial medication, such as the tricyclic clomipramine or the addition of an antipsychotic medication.

Further information about OCD can be found at the links below:

  • Key Facts about OCD (from the Royal College of Psychiatrists, UK website)
  • What is Obsessive-compulsive disorder? (From the American Psychiatric Association)
  • Overview of OCD – its symptoms and signs in addition to main treatments. Also further links for online supports and information. (Helpguide.org – a reliable American online resource for mental health information).

For more resources on psychiatry and mental illness, click here.