Repetitive Magnetic Transcranial Stimulation (rTMS) in the Treatment of Generalized Anxiety Disorder (GAD)

Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive method that holds promise for treating several psychiatric disorders. Yet the most effective location and parameters for treatment need more exploration. Also, whether rTMS is an effective treatment for individuals with a DSM-IV diagnosis of Generalized Anxiety Disorder (GAD) has not been empirically tested. The goal of this pilot study is to evaluate whether fMRI guided rTMS is effective in reducing symptoms of GAD.

This study utilized a 3-week open-label design to evaluate the efficacy of fMRI guided rTMS in the treatment of GAD. We first used functional magnetic resonance imaging (fMRI) during the gambling task to localize anxiety-related brain activations in each individual participant, and then used this information to guide treatment with repetitive transcranial magnetic stimulation (rTMS). TMS was delivered to the target site at a frequency of 1 Hz for 20 minutes (900 total pulses). The intensity of the TMS was set to 90% of the passive motor threshold for each participant. The primary efficacy measures include the Clinical Global Impression of Improvement (CGI-I) and the Hamilton Anxiety Rating Scale (HARS). Response to treatment was defined as a reduction of 50% or more on the HARS and symptom remission was defined as a CGI-I score of 1 or 2 ("much improved" or "very much improved" respectively) and a score ≤ 8 on the HARS. Data was entered anonymously into an Excel spreadsheet and analyzed by the UCLA Semel Institute Statistical Core. The analysis was done on the intent to treat sample using last observation carried forward (LOCF). A one-sample paired t-test was used to compare endpoint to baseline means on the HARS, with a significance level set at p= 0.05, two-tailed.