What if an implant in your brain could reduce your urge for binge-eating? While it may sound too futuristic, Dr Casey Halpern, a neurosurgeon at the University of Pennsylvania, used deep brain stimulation (DBS), a method routinely used to quell tremors in patients with Parkinson’s, in two women with an eating disorder. The device, inserted just under their scalps, stimulated satiety neurons as soon as they picked up the recipients’ brain signals to binge. After a year of keeping the device, both women, who had put on weight despite a bariatric surgery, no longer felt irresistible urges to binge. Now they want their implant to stay!
HOW DBS WORKS
The study, which has been reported in The New York Times, is a remarkable breakthrough, according to Dr Sunit Mediratta, Consultant Neurosurgeon, Apollo Hospital, particularly in times when obesity is an epidemic. Explaining deep brain stimulation (DBS), he says, “Neurologists implant electrodes into the brain in parts that are not working as well as they should. Our brain is the most complex of all organs. It is involved in the control and regulation of most functions of our body, including heart rate, breathing, speech, memory, limb movements, balance, vision, smell, hunger, satiety and many more. Each function is controlled by a specific localised area of the brain. Different areas of the brain are interconnected via complex neuronal circuits with each other to coordinate body functions. It is precisely these neuronal circuits which are difficult to study and result in a visible functional outcome.”
So what are the appetite centres of the brain that we must know about? “The ventromedial nuclei (VML) of hypothalamus is considered to be the satiety centre, and when stimulated, causes the sensation of fullness. On the other hand, the lateral hypothalamic area is the feeding centre and when stimulated, it causes the sensation of hunger. Various hypotheses have been postulated to trigger hunger and satiety responses from the brain. According to the ‘glucostatic hypothesis’, a fall in blood glucose in the fasted state triggers the meal initiation from the lateral hypothalamic area of the brain whereas a rise in glucose after a meal stimulates the VML area and terminates feeding.
The deep brain stimulation (DBS) procedure in patients with binge eating and obesity attempts to address these areas of the brain by implanting electrodes and stimulating the satiety centres or neurons, which result in a feeling of satiety even after a small meal resulting in decreased calorie intake,” says Dr Mediratta.
WHAT THE STUDY MEANS
The DBS procedure carried out by Dr Halpern inhibits the urge to binge-eat by stimulating a group of neurons called nucleus accumbens. “Experimental studies in mice have shown that the neurons in the nucleus accumbens became active just before a binge. When researchers used deep brain stimulation to calm those neurons, they were able to prevent the mice from binging. Success in animal studies prompted him to attempt DBS in humans, and by stimulating the nucleus accumbens via electrodes implanted deep in the brain, he could achieve to calm those neurons. This quells the urge to binge resulting in weight loss,” says Dr Mediratta.
CAN DBS BE USED AS A TREATMENT PROTOCOL FOR OBESITY?
Even though just two people have been treated with this procedure, Dr Mediratta feels it has the potential to radically change the current concept of treatment for extremely obese patients who have to undergo a bariatric surgery for weight loss. “Currently, the bariatric procedures artificially reduce the volume of a patient’s stomach so that he feels full even after a small meal. Many patients gain back the weight after an initial weight loss following the bariatric surgery and have to watch their diet,” he adds.
However, he feels more patients need to be evaluated with DBS before it can become a standard of care. “DBS is likely to have a small risk associated with it, which may include seizures, bleeding and limb weakness among others as the electrodes are implanted deep into the brain and close to areas which serve other critical functions. Although this procedure is still experimental for weight loss, it would be worthwhile if more countries allow neurosurgeons to carry out this procedure on volunteers and analyse results, “ he says.
Once the devices were implanted in the women’s brains, they weren’t told when they would be activated. Both women said they were surprised that they no longer felt that monstrous craving and that their weight was going down slowly and consistently. And they were not thinking obsessively about food.