Obsessive-compulsive disorder (OCD) affects 2 to 3% of the population. OCD is characterised by the appearance, on average around the age of 20 (around the age of 14 in 25% of cases), of ideas or images that are repeated, persistent, unwanted and often anxiety-provoking. These obsessions are often accompanied by repetitive behaviours designed to neutralise the anxiety and anguish resulting from the obsessions, known as compulsions. OCD is considered to be a disease of behaviour, thought and emotion. Around a third of patients with OCD have had, or still have, TIC.
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In severe cases of obsessive-compulsive disorder (OCD), some patients can spend several hours a day performing compulsive rituals, resulting in a major handicap in their daily, family, social or professional life.


The causes and biological mechanisms of OCD

The causes of obsessive-compulsive disorder are unknown, although a non-hereditary genetic component is suspected. However, the brain regions involved in obsessions and compulsions have now been identified. Using functional MRI or magnetoencephalography techniques, researchers have identified dysfunction in two distinct brain areas in the frontal lobe, the orbitofrontal and ventromedial prefrontal regions. Deeper areas of the cortex also play an essential role in these disorders, the basal ganglia.


Symptoms and diagnosis of OCD

The visible symptoms of obsessive-compulsive disorder are repeated behaviours (compulsions), such as excessive and frequent hand-washing, which are simply the consequence of the obsessions suffered by the patients, in this case the irrational fear of being contaminated by a virus or bacteria. These compulsions, or compulsive rituals, reflect an irrepressible need to alleviate or avoid the anxiety or anguish caused by the obsessions.

A large proportion of patients suffering from OCD have concomitant mental disorders. 75% of them suffer from anxiety disorders, and 50-60% have severe depression or are diagnosed as bipolar. The risk of suicide attempts is significantly increased in these patients.

The diagnosis of OCD is based mainly on the clinical signs of obsession and/or compulsion, which must constitute a real waste of time in the patient’s day or cause pathological suffering and distress.


Treatments for OCD

Patients are generally offered two successful treatments for OCD. Ritual exposure and prevention psychotherapy, which consists of putting patients in a situation that generally triggers the obsession or compulsion, while preventing it from occurring. As the sessions progress, the patient gradually becomes aware of the uselessness of the rituals in reducing anxiety until the compulsive need for the ritual, which is fairly constant over time (usually several years), completely disappears.

The second effective therapy is medication based on serotonergic antidepressants, with a combination of the two strategies often constituting the best treatment.

In more severe cases, deep brain stimulation via implanted electrodes may be the only effective therapeutic solution.


Last updated May 2024.