Motor cortical excitability in obsessive-compulsive disorder: Transcranial magnetic stimulation study.

OBJECTIVES: Transcranial magnetic stimulation is a non-invasive method of stimulating the brain that is increasingly being used in neuropsychiatric research. Previous work has suggested that the pathophysiology of obsessive-compulsive disorder (OCD) may involve dysfunction of excitatory and/or inhibitory brain function. This study aimed to extend those findings. METHODS: The study included 45 OCD patients and 15 age- and sex-matched healthy volunteers. Clinical evaluation was conducted using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), Hamilton Anxiety Rating Scale (HAM-A), and Clinical Global Impression rating scale (CGI). Physiological measures were resting and active motor thresholds (RMT and AMT), motor evoked potential (MEP) amplitude, cortical silent period (CSP) and transcallosal inhibition (TCI) durations, short-interval intracortical inhibition (SICI), and intracortical facilitation. RESULTS: RMT and AMT were significantly lower in patients than in the control group. The mean duration of the CSP and TCI were also significantly shorter. Obsessive trait was associated with significant reduction of TCI duration compared to compulsive trait. There was significant reduction in SICI in OCD patients compared to controls. There were no significant correlations between the Y-BOCS, HAM-A and CGI scores and the cortical excitability parameters. CONCLUSION: These results provide further evidence for inhibitory deficits or increased facilitation in cortical circuits of patients with OCD.

Repetitive transcranial magnetic stimulation in the treatment of obsessive-compulsive disorders: Double blind randomized clinical trial.

Repetitive transcranial magnetic stimulation (rTMS) has become widely used as a therapeutic tool in psychiatric research. The aim of this study was to evaluate the impact of different frequencies of rTMS over right dorsolateral prefrontal cortex (DLPFC) in OCD. Forty five patients with OCD participated in the study. Patients were evaluated using: Yale-Brown obsessive compulsive scale (Y-BOCS), Hamilton Anxiety Rating Scale (HAM-A), and Clinical Global Impression-Severity scale (CGI-S). They were randomly classified into three groups: 1st group received 1Hz rTMS; 2nd group received 10Hz rTMS; and 3rd group received sham stimulation all at 100% of the resting motor threshold for 10 sessions. They were followed up after the last treatment session and 3 months later. There was a significant "time"×"group" interaction for 1Hz versus Sham but not for 10Hz versus Sham. 1Hz versus 10Hz groups showed a significant interaction for Y-BOCS and HAM-A (P=0.001 and 0.0001 respectively). 1Hz rTMS has a greater clinical benefit than 10Hz or Sham. There was also a significantly larger percentage change in GCI-S in the 1Hz group versus either 10Hz or sham. We conclude that 1Hz-rTMS, targeting right DLPFC is a promising tool for treatment of OCD.