Neurocognitive effects of repetitive transcranial magnetic stimulation in severe major depression.
BACKGROUND The safety of repetitive transcranial magnetic stimulation (rTMS) has only previously been formally studied in volunteers receiving a single session of stimulation or in a small number of depressed subjects receiving a 2-week treatment course. This study examined safety issues in depressed subjects receiving up to 4 weeks of rTMS. Efficacy results from this study have been previously reported. METHODS Eighteen subjects with DSM-IV major depression participated in a 2-week, parallel, double-blind, sham-controlled study of rTMS treatment. Twelve subjects then went on to receive 4 weeks active rTMS in an open follow-up. We examined the effects of rTMS on neuropsychologic function (up to 4 weeks), auditory threshold (up to 6 weeks exposure to rTMS noise), and an electroencephalogram (after 2 weeks). Data were analyzed by repeated measures analysis. RESULTS There were trends for improvement in neuropsychologic performance, probably due to practice effects. No mean changes in auditory threshold occurred, but two patients showed mild high-frequency hearing loss after several weeks of rTMS. Electroencephalograms in two patients, one of whom had sham stimulation, showed minor abnormality. CONCLUSIONS No significant mean deficits were demonstrated in this cohort. Overall, rTMS for up to 4 weeks is safe, but individual results suggest caution and the need for further investigation of the safety of several weeks of rTMS.