SAN DIEGO — A mild electrical stimulation to a specific brain area could be an effective treatment for some patients with eating disorders such as bulimia, who suffer from episodes of severe binge eating and purging behaviors, researchers say.
After one 42-year-old woman received the electrical stimulation, called transcranial magnetic stimulation (TMS), as a treatment for her depression, and showed an unexpected recovery from her 20-year battle against bulimia nervosa, her doctors conducted a pilot study to see whether the treatment would also work for other patients with eating disorders, said Dr. Jonathan Downar, of the University of Toronto. Downar described the study Tuesday (Nov. 12) here at the annual meeting of the Society for Neuroscience.
In the study, Downar and his colleagues recruited 20 patients with bulimia and stimulated a part of their frontal lobes called the dorsomedial prefrontal cortex, which is next to the brain region usually stimulated for treating depression. The patients, who had already tried conventional therapies and medications but had seen no improvement, received 20 sessions of electrical stimulation daily for four weeks.
At the end of the treatment, six of the patients saw their binge eating and purging symptoms almost completely disappear. In another four patients, symptoms improved by more than 50 percent. Eight patients saw only little improvement, and two got worse, Downar said.
Although larger studies and clinical trials are needed to confirm the results of the pilot study, Downar said he is optimistic about the promise of using TMS for treating certain patients with eating disorders. [ 5 Controversial Mental Health Treatments ]
"There are lots of things you could do to treat disorders like depression, but for these folks [with bulimia], there's really nothing if they have gone through all of the medications" and therapy options, Downar said.
Eating disorders, such as anorexia and bulimia, affect more than 8 million people in North America. These disorders often carry emotional distress, disrupt the person's normal life and can even lead to life-threatening medical problems.
TMS is a relatively new technique, and involves a large electromagnetic coil that is placed over the skull, and changes the activity in a targeted brain region by inducing electric currents. Although the change is temporary and reversible, with repeated stimulation, doctors can create lasting changes in neuronal activity. Repeated TMS has been approved by the U.S. Food and Drug Administration as a treatment for some forms of depression.
In the study, the researchers used brain imaging to examine whether differences in brain activity could explain why some patients respond well to TMS treatment while others show little or no improvement.
They found that before the treatment, responders had lower connectivity between the frontal lobe and a set of brain areas (such as the striatum) that are linked to rewards and cravings. This low connectivity could be a sign of impulsiveness, and stimulation may have helped to make the missing connection in these patients' brains, Downar said.
In contrast, the brains of the people whose bulimia was not helped by TMS appeared more connected in those areas. In these patients, TMS appears to be ineffective in treating bulimia because the brain stimulation is "giving them something they don't need, because they already have it," Downar said.
The brain imaging results suggest that doctors may be able to identify which patients will respond to TMS treatment, and spare others from a weeks-long treatment.
"By using brain imaging to detect these patterns, we may eventually be able to predict which patients are most likely to benefit," Downar said.