From The Quarterly, Fall 2011
A significant minority of people with depressive illness fail to respond to any currently available antidepressant medication. However, new methods of brain stimulation offer the possibility of relief from their symptoms. These technologies exploit the fact that the brain is an electrical organ: it responds to electrical and magnetic stimulation to modulate brain circuits and change brain activity.
Electroconvulsive therapy (ECT) is the gold standard in brain stimulation technology. Modified to avoid the pain previously associated with it, it is the most effective and quick-acting treatment for treatment-resistant depression and useful as well in treating mania in bipolar disorder and the psychosis of schizophrenia. The downside of ECT, which works by inducing brain seizures, is that it can impair memory and its therapeutic benefits can fade over time.
Deep brain stimulation (DBS), a technique adapted for treating depression by NARSAD Investigator and Scientific Council member Helen Mayberg, M.D., works through electrodes planted deep in the brain. It often works when ECT fails. Another method, vagus nerve stimulation (VNS), stimulates the vagus nerve in the neck to therapeutically activate brain function.
Among technologies that use magnetic fields to rouse brain activity, repetitive transcranial magnetic stimulation (rTMS), pioneered by NARSAD Investigator and Scientific Council member Mark George, M.D., was recently approved by the FDA as a treatment for some otherwise untreatable depressions. A noninvasive method that does not induce seizures, it works through a coil held over the target area of the brain. A magnetic field passes through the skull to activate the appropriate brain circuit.
Magnetic seizure therapy (MST), a major area of Dr. Lisanby’s research, combines rTMS and ECT to achieve a safer form of seizure therapy. MST couples TMS’s careful focus and noninvasiveness with the effectiveness of ECT while sparing ECT side effects, such as memory impairment.
Beyond their potential effectiveness as treatments, brain stimulation technologies are proving to be powerful research aids. While neuroimaging techniques can reveal linkages between brain circuits and behavior and function, they are basically passive tools. By contrast, brain stimulation can actually change brain function, and in so doing make it possible for researchers to explore outcomes of brain-circuit manipulation and test ideas about how the brain works.