Lack of significant changes on magnetic resonance scans before and after 2weeks of daily left prefrontal repetitive transcranial magnetic stimulation for depression

Repetitive transcranial magnetic stimulation (rTMS) is a new technology for exploring brain function. With this method, a small electromagnet is place d on the scalp; by activating and deactivating it, nerve cells in the under lying superficial cortex are depolarized. Several studies have found that p refrontal rTMS has potential efficacy in treating depression, and this tech nology, in addition to being a research tool, may soon play a role in psych iatric practice. Thus, establishing the safety of this technology is import ant and has been studied insufficiently. The authors performed T1-weighted three-dimensional volumetric magnetic resonance (MR) imaging on 22 depresse d adults (15 active, 7 control) before and after they participated in a 2-w eek double-blinded, placebo-controlled trial of daily left prefrontal rTMS for the treatment of depression (a total of 16,000 stimuli). Seventeen pati ents also had paired T2-weighted scans. In a blinded manner, MR scans were qualitatively and quantitatively assessed for structural changes. No qualit ative structural differences were observed before and after treatment. In a ddition, volumetric analysis of the prefrontal lobe showed no changes in th e 2 weeks of the study. In conclusion, 10 days of daily prefrontal rTMS at these intensities and frequencies does not cause observable structural chan ges on MR scans in depressed adults.