New Developments in Repeated Transcranial Magnetic Stimulation (rTMS)
At the 65th Annual Scientific Convention of the Society of Biological Psychiatry, several findings related to repeated transcranial magnetic stimulation (rTMS) were reported.
E. Baron Short reported that two weeks of 10 Hz rTMS at 120% of motor threshold (MT) was highly effective in the treatment of fibromyalgia. Pain ratings decreased 45% by day six and 80% by day 10 in this randomized sham-controlled double-blind study.
Also at the convention, Motoaki Nakamura reported that either 1 Hz or 20 Hz rTMS at 90-100% of motor threshold over left prefrontal cortex in depressed patients increased gray matter in left dorsolateral prefrontal cortex and left hippocampus in association with almost 50% reductions in Hamilton depression rating scale scores and associated increases in performance on the Wisconsin card sort test.
Editor’s note: These data are of particular interest in light of increasing evidence for prefrontal and hippocampal neurochemical and volumetric deficits in major depression and other evidence that rTMS may be capable of increasing neurotrophic and neuroprotective factors. This is the first clinical evidence suggesting that rTMS may have direct effects on brain volume as well. These data would converge with other data indicating that long-term antidepressant therapy can prevent hippocampal atrophy and short-term lithium can increases gray matter and hippocampal volume.
The first large multi-center study of rTMS, which was sponsored by industry, gained FDA approval for the apparatus. As reported in previous BNNs, Mark George and collaborators conducted a second large multi-center study sponsored by the National Institute of Mental Health (NIMH), which indicated that rTMS can produce significantly greater rates of remission than those achieved by sham rTMS, as reported in the Archives of General Psychiatry this year. Hopefully, these new efficacy data by George and colleagues will increase the ease of receiving insurance reimbursement for the expensive procedures of a full course of rTMS for the treatment of an acute depression that has been unresponsive to at least one prior clinical trial of an antidepressant.
The data of Nakamura et al. noted above are also of interest in relationship to data from a study in which this editor participated (Speer et al., 2010), which indicated that both 1 Hz and 20 Hz stimulation were more effective than sham rTMS in improving the condition of patients with highly treatment-refractory depression. Moreover, in that study, we observed that 1 Hz rTMS at 110% of a patient’s motor threshold decreased brain activity as measured with cerebral blood flow on PET scan, while 20 Hz markedly increased brain activity in a widespread fashion that remained for at least 48 hours following the last of 15 rTMS sessions spread over a period of three weeks. The Nakamura data indicating that both 1 and 20 Hz increase indices of gray matter in left dorsolateral and left hippocampus suggests that this neurotrophic effect may, in fact, occur at both high and low frequency rTMS, even though they produce opposite effects on brain activity.
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