U.S. News on TMS for Depression

Great article from U.S. News on TMS Therapy as a leading form of treatment for depression

It’s been called “brain zapping” and “jumper cables for the mind.” Scientists prefer the more professional-sounding neologism electroceuticals. Whatever you call it, the interest in using electricity to treat certain types of mental disorders, including depression, is growing rapidly. That’s because numerous studies over the past several years show that it works.

The National Institute of Mental Health says conservatively that brain stimulation therapies “can play a role in treating certain mental disorders.” Brain stimulation therapies, the NIMH explains, involve activating or inhibiting the brain directly with electricity. The electricity can be given directly by electrodes implanted in the brain or noninvasively through electrodes placed on the scalp. The electricity can also be induced by using magnetic fields applied to the head. “While these types of therapies are less frequently used than medication and psychotherapies, they hold promise for treating certain mental disorders that do not respond to other treatments,” the NIMH concludes.

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Magnetic-field stimulation is especially useful in treating depression, its advocates say. One particularly strong advocate of this treatment is Marom Bikson, a professor of biomedical engineering at the City College of the City University of New York. “It is not mainstream yet, and most providers are not using it yet, but the ones who are really have studied it and embraced it as a good option for their patients,” Bikson says. “Some are even specializing in it.”

Magnetic Possibilities

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There are two main types of magnetic therapies. The first, called repetitive transcranial magnetic stimulation, or rTMS, involves using a wand attached by cable to a wall outlet. The wand is positioned over the head and delivers magnetically generated electricity to the brain. "The magnetic field travels through the hair, skin and skull because they do not conduct electricity," says Dr. Joan A. Camprodon, director of neuropsychiatry and neuromodulation at Harvard Medical School and director of the transcranial magnetic stimulation clinical service at Massachusetts General Hospital. "When it gets to the surface of the brain it interacts with brain cells, which do conduct electricity. The brain's neurons act as a pickup coil and turn the field back into electricity, which forces the neurons to fire."

The second, called transcranial direct-current stimulation, or tDCS, is a smartphone-sized unit that contains its own 9-volt battery. Two wires with electrodes extend from the device and are placed on the head.

“Both use electricity, but the way they deliver electricity is very different,” Bikson says. rTMS produces more intense stimulation, about 200 milliamps, but over a short duration of a few seconds. The electric current coming out of a tDCS device is about 2 milliamps, which is about a tenth of the current used by a night light, but it is delivered for an extended period of time, about 20 minutes. (By way of comparison, electroconvulsive therapy uses about 800 milliamps, which is enough to cause a controlled seizure.)

Electrical stimulation works because the brain is an electrical organ, Bikson says. “The connections are electrical, and all brain function and dysfunction can be conceived of as how this electrical system functions.” Shocking the brain changes that system. “If you do it right, that can produce after effects, so when you’re done the brain has changed,” he says.

Depression, he says, is believed to be caused by electrical dysfunction of one region of the brain, known as the dorsolateral prefrontal cortex. “The notion is that that part of the brain is not as active in a depressed patient as in a healthy individual, so stimulation applies electricity to try to boost its function to behave more like a normal dorsolateral prefrontal cortex.”

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Just Scratching the Surface

In 2008, the Food and Drug Administration approved rTMS as a treatment for major depression for patients who do not respond to at least one antidepressant medication in the current episode. A large clinical trial, funded by NIMH and published in 2010, found that 14 percent of depression patients achieved remission with rTMS compared to 5 percent with a placebo treatment. Camprodon adds that about 70 percent of those who improve with treatment are still better a year later.

 

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Its counterpart, tDCS, has not been approved yet by the FDA. It is a newer technology, discovered only around 2000, Bikson says. “The overall consensus is that it shows promise for depression, but it has not yet had the multicenter trials that would get it FDA approval,” he says. If and when it is, it has the potential to be prescribed as an at-home treatment, whereas TMS will likely remain based in a clinical setting, Camprodon says.

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Electrical stimulation is not a first-line treatment option. But for those suffering major depression, it can be a life-saver when nothing else helps, Bikson believes. “Something that can transform the life of one person is in a sense revolutionary. There is strong evidence that, for some individuals who failed to respond to everything else, stimulation doesn’t necessarily cure them but it puts them on a path toward healing and rebuilding their life. Because of that I am really enthusiastic. It is not for everyone, it is not going to replace drug therapy, but in my mind it could be as big as drug therapy.”

Bikson sees great strides being made in the coming years. “We are at baby aspirin levels of dosage and flip-phone levels of technology,” he says. “We have not even scratched the surface. We haven’t seen anything yet in the potential of electroceuticals.”