Treating Social Cognition With Theta Burst Stimulation: a Multicentric Study (TBS-COG)

The language understanding of other people is based on linguistic decoding mechanisms (phonological, semantic, syntactic ...) but also more on subtle mechanisms for the recognition of emotions and intentions. Interact with another one requires understanding its language but also to infer emotions and intentions. There are patients with schizophrenia suffering from social cognition disorders that impair social interactions; These patients often have difficulty in extracting the non-verbal emotional content of language and have difficulty inferring the thoughts and intentions of others. Recently, investigators have suggested a link between such deficits and the hypofunction of the medial prefrontal cortex.

Transcranial magnetic stimulation is a noninvasive neuromodulation technique that increases or decreases the focal cortical excitability depending on stimulation parameters. This technique is now commonly used as a therapeutic tool. It has been tried with some success in patients with schizophrenia in some indications:

• To reduce the auditory verbal hallucinations stimulating the temporal cortex
• More rarely, to reduce the negative symptoms stimulating the dorsolateral prefrontal cortex.

So far, the medial prefrontal cortex was not considered as a possible target as the scalp to cortex distance prevent from using conventional stimulation coils. Recently new coils have been developed that permit stimulation of deeper cortical regions.

Investigators hypothesize that the use of transcranial magnetic stimulation with a theta burst intermittent protocol known to increase the cortical excitability and aiming the medial prefrontal cortex with a special antenna will improve social interaction capabilities of schizophrenic patients.

In this multicentric study, involving 61 patients, investigators plan to assess the social cognition deficits before and after 10 sessions of magnetic stimulation (2 sessions per day for 5 consecutive days) using a neuronavigation system and Magstim® stimulator. In order to assess the specificity of the stimulation of medial prefrontal cortex (MPC), the effects of this treatment will be compared to the effects of the same treatment aiming the dorsolateral prefrontal cortex (DLPFC), also involved in aspects of negative symptoms of schizophrenia, and placebo effects induced by sham stimulation (using a sham coil). An anatomical MRI will be performed before the treatment to define the targets. Moreover, changes motor activity will be observed after stimulation thanks to continuous actimetry recording.