Scientists from the University of Nottingham in the U.K. say they have a new understanding of how transcranial magnetic stimulation (TMS) gives relief to severely depressed patients.
TMS, used as an alternative to electro-convulsive therapy (ECT), works by applying a magnetic pulse to the front part of the brain of depressed patients. Like ECT, it seems to “reset” the brain, but is easier to use because it does not require an anesthetic, and has few side effects, according to the researchers. Because of this, it is increasingly used in the treatment of depression.
However, TMS, like ECT, is something of a blunt instrument, as scientists had a limited idea of how it works. The new study has shown that targeted magnetic pulses causes biochemical and connectivity changes across the brain.
This new finding could open the door to better, more targeted treatment for depression and other conditions, according to the researchers.
In the placebo-controlled study, researchers applied MRI-guided targeted bursts of magnetic pulses to the dorsolateral prefrontal cortex in the brains of 27 healthy volunteers. Using the same MRI scanner, they were able to measure the subtle functional changes in the brain caused by the magnetic pulses. They were also able to measure the changes in brain chemistry, using magnetic resonance spectroscopy.
“We found that one session of TMS modifies the connectivity of large-scale brain networks, particularly the right anterior insula, which is a key area in depression,” said lead researcher Dr. Sarina Iwabuchi. “We also found that TMS alters concentrations of neurotransmitters, such as GABA, which are considered important for the development of depression.”
“These results mean that, for the first time, we have an understanding of the direct effects TMS has on the brain,” she said. “If we can see the change caused by the treatment, then treatment can be smarter. It also means that treatment can be better tailored to each individual’s brain — in other words, this could be personalized treatment for depression.”
The study presented at the annual conference of the European College of Neuropsychopharmacology showed that personalized TMS treatment is possible, “and does indeed lead to brain changes,” Iwabuchi noted.
“The next step is to use it as a practical treatment for patients with depression in a clinical trial setting, and in fact this trial in now underway in Nottingham,” she added. “These are the first steps to personalizing this treatment.”