05 May 2008

Possible causes of OCD

Prof Christine Lochner discusses the latest research on the causes of obsessive-compulsive disorder.

Knowledge about obsessive-compulsive disorder (OCD) has increased much in the last two decades. This research has shown that there is no single, proven cause of OCD. Most probably it is the interaction amongst a number of factors, including genetics, which lead to the development of OCD.

For example, based on increasing brain imaging and research efforts, it is known that the brain activity of people with OCD differs from normal individuals and those with other anxiety disorders. Research also suggests that OCD involves problems in communication between the orbital cortex (the front part of the brain) and the deeper structures (the basal ganglia). Indeed, OCD is occasionally seen in people with basal ganglia lesions.

Furthermore, there is growing evidence that specific brain circuits mediate OCD. Various neurochemical systems, including the serotonin and dopamine systems, are thought to be important in mediating OCD symptoms. Neuroimmunological factors may also play a role in the development of OCD.

A number of patients associate the onset of their OCD with an infection, possibly bacterial pharyngitis. Hormonal influences have also previously been investigated in OCD. For example, it has been noted that menarche, premenstruum (the few days preceding menstruation), pregnancy and menopause may be related to onset or relapse in OCD.

The role of childhood trauma (for example emotional neglect) as well as the influence of temperament/character, in the development of OCD have also been investigated.

Furthermore, there is increasing evidence that OCD may be inherited, i.e. that there is a role for genetics in the development of this condition. Indeed, family and twin studies indicate that OCD is somewhat more common in relatives of people with OCD or Tourette's disorder than in the general population. In other words, the risk of getting OCD for a person with family members with OCD is higher compared to others. This is a rapidly advancing area of research and several candidate genes for OCD have already been proposed (for example catechol-O-methyl transferase).

Comorbid conditions
It has been suggested that a range of comorbid psychiatric disorders is commonly seen in OCD, with depression the most frequent of these. In one study (by Eisen et al, 1999) it was found that the most common comorbid diagnosis was major depressive disorder (55%), followed by social phobia (23%), simple phobia (21%), and generalised anxiety disorder (20%). Comorbidity with post traumatic stress disorder (PTSD) has also been shown. - Prof Christine Lochner, researcher at the MRC's Unit on Anxiety and Stress Disorders.

Research participants needed
If you have OCD, you can participate in a research project on OCD and genetics. Contact Prof Christine Lochner on 021 938 9179 or via e-mail: or Ms Jemona Mostert on 021 938 9762, email: for more information.


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