The Use of Magnetic Brain Stimulation to Treat Obsessive Compulsive Disorder, a Pilot Study

The Efficacy of Repetitive Transcranial Magnetic Stimulation (rTMS) in the Treatment of Obsessive Compulsive Disorder (OCD), a Pilot Study

The purpose of this study is two-fold: first, to observe the effect of one session of repetitive transcranial magnetic stimulation (rTMS) on the error-prediction abilities of patients with obsessive compulsive disorder (OCD) as well as healthy individuals; and second, to observe the clinical effect of 10 sessions of rTMS in patients with OCD.

A battery of cognitive tasks designed to selectively measure several aspects of anterior cingulate cortex (ACC) function, will be administered before and after one session of rTMS in all participants. The first neurocognitive session will be administered in a separate day from the rTMS session. The second neurocognitive session will be performed immediately after rTMS and in the same day. Participants will perform five tasks designed to test: error processing, error likelihood assessment, meta-memory, response inhibition, and affect recognition. The rTMS paradigm will consist of four short trains of magnetic pulses which include 5 minutes of stimulation with 1Hz frequency (overall 1200 pulses in one session) with an intensity of 110% of each participant's motor threshold, and 2 minute intervals between the stimulation trains. Stimulation will be applied over the dorsal ACC (dACC) using a double-cone rTMS coil. dACC will be precisely targeted using neuronavigation software loaded a high resolution MRI of each subjects' brain. OCD patients will go on to receive two weeks (10 sessions) of daily rTMS treatments using the same protocol described above.

Ten sessions of 1Hz repetitive Transcranial Magnetic Stimulation of the dorsal anterior cingulate cortex in patients with obsessive compulsive disorder

One session of 1Hz repetitive Transcranial Magnetic Stimulation of the dorsal anterior cingulate cortex in healthy control individuals

Yale-Brown Obsessive Compulsive Scale. Minimum value = 0. Maximum value = 40. Higher scores indicate greater severity of obsessive and compulsive symptoms.

Post-error slowing (PES) is the difference in response time on trials following an error to trials following a correct response. Higher numbers indicate more post-error slowing (i.e. longer response times following an error trial compared to following a correct trial). The outcome measure is the change in PES from baseline to following one session of rTMS.

Inclusion Criteria: Diagnosed obsessive compulsive disorder Not currently receiving cognitive behavioural therapy Not currently on any medication or only taking one selective serotonin reuptake inhibitor (SSRI) Exclusion Criteria: History of psychotic episodes History of neurological illness Previous head injury Active alcohol or substance abuse History of seizure disorders Currently pregnant

Modirrousta M, Meek BP, Sareen J, Enns MW. Impaired trial-by-trial adjustment of cognitive control in obsessive compulsive disorder improves after deep repetitive transcranial magnetic stimulation. BMC Neurosci. 2015 Oct 9;16:63. doi: 10.1186/s12868-015-0205-z.