How coil-cortex distance relates to age, motor threshold, and antidepressant response to repetitive transcranial magnetic stimulation

Repetitive transcranial magnetic stimulation (rTMS) is a fool with antidepr essant potential that uses a coil placed on the scalp to produce a powerful magnetic field that directly stimulates only the outermost cortex. MRI sca ns weve obtained in 29 depressed adults involved in an rTMS antidepressant clinical treatment. These scans were analyzed to investigate the effect of distance from coil to cortex on clinical parameters. Longer motor cortex di stance, but not prefrontal distance, strongly correlated with increased mot or threshold (P < 0.01). Clinical antidepressant response did not correlate with either distance. The rTMS antidepressant responders, however, were si gnificantly younger (t = -2.430, P < 0.05), and there appears to be a maxim um threshold of age and distance to prefrontal cortex for response.