Obsessive-compulsive disorder (OCD) is a disabling disease both for the subject suffering from it and his relatives.
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OCD manifests itself in 2 main symptom categories : obsessions in the form of thoughts, and unpleasant content images, which are imposed involuntarily to the subject. These obsessions are a major source of anxiety and require the completion of repeated behaviours from the subject, rituals to try to ease these distressing thoughts.

Currently, cognitive-behavioural psychotherapy treatments (CBT), and / or serotonergic antidepressants can improve two-thirds of patients. However, conventional therapy resistant forms and, in particular, very severe forms (20% of all resistant forms) are subject to specific research to develop therapeutic innovations.


2% to 3% of the population are affected by OCD. Today, it is the 4th most commonly treated illness in psychiatry after phobic disorders, addictions, and depressive disorders. This disease can appear early, as early as childhood, with chronic evolution : 65% of affected people have declared this disorder before 25 and 15% after 35.

Institut du Cerveau – ICM RESPONSES


Understand the mechanisms at the origin of obsessive-compulsive disorders and develop innovative solutions to treat them : Luc Mallet’s team.

Luc Mallet, Psychiatrist and neuroscientist, and his team develop basic and clinical research projects to try to understand the brain functions involved in the pathology by studying behaviour both in the experimental model and in human.

From brain neuroimaging techniques, researchers were able to identify that some cortex areas, orbito-frontal areas (located above the eyes) are involved in the emergence of some of the most important symptoms, including invasive doubt, probably being at the origin of compulsive checking behaviours.

In addition, the team wishes to offer innovative solutions, especially in most resilient forms, using different therapeutic approaches such as experimental psychotherapy, use of transcranial stimulation, or deep brain stimulation. Through this last technique, researchers have recently discovered that by modulating the activity of very specific brain circuits, the symptoms expressed in the disease could be attenuated or totally removed. This approach consists in modulating dysfunctional brain circuits activity. These networks need to be better identified to hopefully increase the therapeutic effect.


Treat OCD through deep brain stimulation

Different clinical trials aiming to assess high frequency brain stimulation effectiveness have been developed and carried out at the Institut du Cerveau – ICM. Carine Karachi and Luc Mallet are involved in several multicentric trials and have coordinated a trial aiming to compare several stimulation targets in patients. At the same time, they coordinate electrophysiology research aiming to identify status and response biomarkers in patients. The objective of these trials is to optimise OCD treatment by deep brain stimulation.