05 May 2010

Transcranial Magnetic Stimulation Lightens Depression

A recent Medical University of South Carolina study of transcranial magnetic stimulation (TMS) to treat depression, supports the use of TMS in medication-resistant depression. A large number of depressed persons do not respond to medical antidepressant therapy, leading to significant disability and suffering.
A sample of 190 patients who had previously failed to respond to antidepressant medications received at least three weeks of randomized, controlled magnetic stimulations on weekdays for three weeks, with the rTMS magnet aimed at their brain's left prefrontal cortex. Those who showed improvement received up to an additional three weeks of such blinded treatment.

Thirteen (14 percent) of 92 patients who received the active treatment achieved remission, compared to 5 (about 5 percent) of 98 patients who received the simulation treatment. Patients who received active rTMS were significantly more likely to reach remission, particularly if they had been moderately, rather than severely, treatment resistant. The remission rate climbed to nearly 30 percent in an open-label phase of this study in which there was no simulation control. George said this is comparable to rates seen in the STAR*D medication studies. However, the researchers note that "the overall number of remitters and responders was less than one would like with a treatment that requires daily intervention for three weeks or more, even with a benign side effect profile."

Patients who responded to active treatment received up to three weeks of additional blinded, controlled rTMS until they achieved remission or stopped showing a meaningful response -- so the number of responders did not differ significantly from the number of remitters. These patients who remitted then received a combination of medications intended to help maintain the treatment effect. Despite failing to respond to medications in the past, most remained in remission for several months.

Study participants who failed to improve during the blinded phase entered a course of open-label rTMS. Among those who had been in the active rTMS group, 30 percent achieved remission during this second phase. This suggests that some patients might require as many as 5-6 weeks of daily rTMS treatment, according to George. Most patients who remitted required 3-5 weeks of treatment.
"For treatment resistant-patients, we found that rTMS is at least as good as current medications or anything else we have available, except ECT," said George. "Our current antidepressants do not work for many people."

Since the rTMS treatment did not trigger any seizures or notable side effects, the researchers propose that higher levels of magnetic stimulation be used in future studies, as evidence suggests antidepressant effects of such stimulation are dose-dependent. Higher remission rates might also be attainable if rTMS were combined with medications, they suggest.
Using magnetic resonance imaging (MRI) scans of patients' brains showing exactly where the magnetic coil was positioned, the researchers hope to confirm earlier findings suggesting that a more forward and to-the-side placement produces a larger therapeutic effect. They plan to report the results of the MRI analysis at the American Psychiatric Association meeting in late May. _SD

Large number of links to more information on TMS

TMS should not be confused with deep brain stimulation (DBS) or electroconvulsive therapy (ECT). DBS requires implanting electrodes inside the brain, and ECT involves electric shock under anesthesia, designed to trigger short term seizure activity.

The field of electromagnetic stimulation of the brain for therapeutic purposes is still in its infancy. As better forms of real-time imaging of brain activity are developed, innovations in brain stimulation will allow for real-time monitoring of the effects of the stimulation on the physiological level. In other words, the stimulation will be "dialed in" to a physiologic and subjective "sweet spot" of effect. Stimulators and monitors will be lightweight and small enough to be carried unobtrusively, and easily available for situational adjustments and calibration.

And that will be just the beginning. The danger to humans will be the temptation to succumb to "easy bliss" while neglecting some of the more difficult lessons and transitions which are absolutely necessary for living a full and satisfying life. Of course, we are a long way from that concern -- at least using this technology -- for the masses of humankind.

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