Deep Brain Stimulation May Boost Memory

Jan. 30, 2008 -- Deep brain stimulation may boost memory, Canadian doctors reported today.

Deep brain stimulation is used to treat conditions including Parkinson's disease, essential tremor, and multiple sclerosis. Surgeons implant electrodes at certain spots in the brain and use electricity to stimulate those parts of the brain.

Toronto Western Hospital's Clement Hamani, MD, PhD, and colleagues performed deep brain stimulation on a 50-year-old man who was morbidly obese.

Deep brain stimulation isn't a typical treatment for obesity. But the patient had already tried other obesity treatments and refused to get weight loss surgery, such as gastric bypass.

After informing the man about the procedure's risks -- and getting his approval -- the doctors performed deep brain stimulation. They positioned the electrodes to target a brain area called the hypothalamus, in the hopes that stimulating the hypothalamus would curb eating.

When the electrodes were stimulated at a certain threshold, the man reported feeling like he was about 20 years old, in a park with the friends and girlfriend he had had at that age. And those memories got more intense at higher thresholds.

Later, the man performed better on a memory test while the electrodes were being stimulated, compared with his test performance when the electrodes were off.

"It may be possible to apply electrical stimulation to modulate memory function," the researchers write in today's advance online edition of the Annals of Neurology.

As for the patient's weight, deep brain stimulation wasn't the answer.

The man weighed nearly 420 pounds before getting surgery to implant the deep brain stimulation electrodes. His weight didn't budge during the first six months of deep brain stimulation. After that, his doctors tried deep brain stimulation at a lower frequency, and he lost about 26 pounds over five months without changing his diet or activity; he said he didn't crave food or want to binge eat as much as he had in the past.

But then the patient decided to turn off his deep brain stimulator on some evenings because he "had a desire to eat and he felt it might help him sleep," write the researchers. Over five months, the patient regained the weight he had lost.