University of Oxford

Obsessive Compulsive Disorder (OCD)

Obsessive Compulsive Disorder (OCD)

 Definitions & clinical picture:

The characteristic features of obsessive compulsive disorder (OCD) are the presence of obsessions and compulsions which interfere with the patient’s ability to cope with their daily life.

Obsessions: are unpleasant or distressing thoughts, images or impulses that come to mind over and over again despite conscious efforts to stop them. We all become preoccupied by particular thoughts at times, or have the experience of an irritating tune running again and again through the mind. These normal thought processes are distinguished from obsessional thoughts because it is possible to distract oneself by thinking or doing something else, and because the thoughts do not interfere with normal functioning. In OCD obsessional thoughts are rarely this innocuous. Common themes for the thoughts include violence, sex, contamination and blasphemy. Obsessional images may be of violent or gory scenes that come vividly to mind again and again, and cannot be ignored or suppresses. An obsessional impulse might be a recurrent impulse to hurt someone, usually someone the sufferer would not consciously wish to hurt. For example, a man might have the obsessional impulse to stab his wife, despite having no wish to harm her and finding the impulse distressing. It is uncommon for people to act on obsessional impulses. It is important to distinguish obsessional thoughts from thought insertion, a first rank symptoms of schizophrenis, in which the patient believes they are experiencing thoughts that are not their own. In contrast, obsessional thoughts are always recognized as arising from the patient’s own mind (ego-syntonic vs. ego-dystonic).

Compulsions: are the behavioural counterparts of obsessions, with a strong urge to perform an action or complex serious of actions (overt or covert) repeatedly, even though they are recognized as unnecessary. Compulsions can often be resisted for a short periods, but that can only be relieved by performing the compulsive act. Compulsions can take very many forms, but the commonest are:

  • Hand washing and other cleaning behaviours
  • Counting, e.g. repeatedly counting objects in the room or avoiding particular numbers
  • Checking, e.g. returning home again and again to check the oven has been turned off or the door is locked.
  • Touching, e.g. feeling compelled to touch each wall of every room entered.
  • Arranging objects in lines, patterns, numbers, etc.

Complex rituals incorporating many of these compulsive acts may be developed and can be very handicapping (may take up to 12 hours a day!)

The clinical picture n OCD is very variable. Patients may have obsessions only, compulsions only, or combination of both. There is a very close relationship with depressive disorders. About 70% have at least one episode of depression at some time in their life, and the two disorders can co-exist (comorbidity). More commonly, patients with depressive disorder can develop obsessional symptoms without having the full blown OCD. In these cases treatment of the depressive disorder is usually enough to resolve the obsessional symptoms completely without other more specific treatments.


OCD is relatively common, with a lifetime prevalence of 2 to 3 %. Unusually for the neurotic disorders it is equally common in men and women. It tends to begin in adolescence and occasionally in childhood.


There are many theories about the aetiology of OCD but like other mental illnesses it is properly multi factorial and bio-psycho-social:

  • Biological factors: are likely to be of importance. Serotonin is likely to play a role in OCD, and drugs which enhance serotonergic activity in the brain are effective treatment
  • Genetic factors: also appear to support the biological role. Abnormal personality may increase the vulnerability to OCD up to 70 %.
  • Psychological (cognitive, behavioural and psychoanalytical theories) all point out that obsessions and compulsions develop to reduce anxiety. The compulsions may be learned behavior that is rewarded with a lessening in anxiety and therefore will be repeated. Alternatively, the symptoms may be considered to arise as a defense against thoughts and feelings that are uncomfortable and cannot be faced. For example, a patient who, as a result of early parental influences, believes that sex is dirty may find that sexual fantasies provoke anxiety. This anxiety may be avoided if the ‘dirty’ thoughts are defended against by the development of compulsive cleaning rituals (the analytical model is the weakest in term of evidence).


A full psychiatric history, mental state examination, rating scales (the Yale-Brown), physical examination and investigations are required in all cases. Some differential diagnoses are: (‘psychiatric’ or ‘organic’)

  • Ø Depression
  • Ø Schizophrenia
  • Ø Tourettes syndrome
  • Ø Dementia (e.g. herpes simplex dementia)
  • Ø Epilepsy
  • Ø Head injury

1. Pharmacological treatment:

Antidepressant which act on serotonin, such as SSRIs and the tricyclic clomipramine are effective in some cases, even if there is no depression. If one SSRI fail, one could try a different one (unlike depression). Also unlike depression, it takes usually longer time and higher doses for the medications to work.

2. Psychological treatment:

It is often helpful to begin first with drug treatment before embarking on psychological treatments, as it may allow the patient to work more effectively with the therapist.

Despite the psychoanalytical theories about aetiology of OCD, psychodynamic psychotherapy is generally of little benefit (lack evidence based support). Cognitive behavioural therapy; on the other hand; has a strong evidence based support and despite that it is not as effective as in depression or anxiety disorders, it is still has a good response rate.

3. Psychosurgery:

Still an option in severe cases. Done in specialized centers. Extremely sophisticated and use laser and Gamma knife in very specific and targeted brain areas. Can be life saving, improve quality of life dramatically. Rarely used.

4. Social treatment:

OCD can be a chronic and very disabling condition that can result in social isolation, unemployment and financial problems. It is important to consider these issues, and where appropriate involve an occupational therapist or social worker in patient’s care.

Course & prognosis:

OCD tends to be a chronic illness, with fluctuations in severity. If treatment is effective it is important to consider the long-term prevention of relapse. Education of the patient and their family about the disorder, and identification of the early signs of relapse with rapid reintroduction of treatment is helpful.



1. Stevens L, Rodin I, Psychiatry: An illustrated colour text, Churchill Livingstone 2001

2. Steple D. Oxford Handbook of Psychiatry, Oxford University Press, 2006

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