Magnetic pulses from a device applied to the head appear to "reset" the brains of depressed patients, according to a new study from the United Kingdom. The circuitry in a part of the right prefrontal cortex is known to be too active in depressed patients, causing excessive rumination and self absorption and impaired attention. When the TMS was applied to healthy subjects in this study, the activity in that region slowed.
"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," lead scientist Sarina Iwabuchi, told the European College of Neuropsychology at a conference in Amsterdam this week.
This was the first time an MRI was used to guide the TMS impulses and, at the same, time measure subtle changes in brain circuit activity. In addition, the researchers used magnetic resonance spectroscopy to analyze subjects' brain chemistry.
"We also found that TMS alters concentrations of neurotransmitters.
Iwabuchi said, "which are considered important for the development of depression," and which are the targets of most current antidepressant medications.
Transcranial Magnetic Stimulation is the use of an electromagnetic coil to deliver small, powerful bursts of energy to targeted areas known to be involved in mood regulation. It is a painless, non-invasive treatment than involves no drugs, no IVs, or any other kind of sedation, and whose chief possible side effect is a headache. (The Food and Drug Administration approved limited use of TMS in 2008 for the treatment of depression.)
The importance of a new tool to treat depression, say experts, cannot be understated. It's been more than 30 years since a truly new medication has come on the market and for those with intractable depression, TMS could be a much-needed alternative. Previously, when multiple courses of drugs have not helped, electroconvulsive therapy was often a patient's only option. Formerly known as shock treatment, ECT has been around for decades, requires anesthesia, and the electricity delivered to the brain is much more direct and much less targeted than with TMS. Scientists also have little understanding about why electroconvulsive therapy works, when it does. Its side effects, including memory loss, can also be significant.
"These findings are an exciting step in understanding how targeting the brain activity with magnetic stimulation may exert beneficial effects in the treatment of depression," said Prof. Catherine Harmer on behalf of the European College of Neuropsychology. "TMS techniques are still evolving . . . This kind of experimental medicine study is therefore essential for the improved personalization and treatment of depression in the future."