An experiment using deep brain stimulation to control appetite unexpectedly improved a patient's memory, a finding that might offer a new way to treat memory disorders, researchers said this week.
Writing in the Annals of Neurology, researchers said that electrodes implanted in the brain of an obese 50-year-old man stimulated vivid memories from the patient's youth and improved his recall on verbal memory tests. The effect disappeared when the electrodes were turned off.
Deep brain stimulation is approved to treat essential tremors and Parkinson's disease. The electrodes, which are permanently implanted in the brain, are powered by batteries and can be turned on and off with an external controller.
The experimental surgery -- the first of its kind to treat obesity -- was a last resort for the man, who weighed 420 pounds and had experienced no success with diets, weight-loss drugs and psychological counseling.
The man, who had diabetes and other health problems, had refused gastric bypass surgery, believing it would not curb his eating.
The electrodes were placed in the hypothalamus, an almond-size area of the brain that regulates hunger, among other things. The theory was that electrical stimulation of the hypothalamus would reduce the man's appetite. The man was fully awake during surgery.
When the electrodes were activated in the operating room, the man suddenly recalled being in a park with friends 30 years earlier. He did not see himself in the scene but recognized an old girlfriend. When the electrical charge was increased, details became more vivid.
Months later, the man was given verbal memory tests with and without the electrical stimulation. His scores tripled with the electrodes switched on.
Andres Lozano, a neuroscientist at Toronto Western Hospital in Canada and senior author, said his team is now testing deep brain stimulation in patients with early Alzheimer's disease.
The procedure was successful in curbing the patient's appetite. But that was not enough. The man turned the electrodes off at night, and when he did so, he ate, Lozano said.