Deep Brain Stimulation for Obesity

Can electrodes implanted in the brain reset a person's metabolism and curb binge eating? The first human test of deep brain stimulation of the lateral hypothalamic area (LHA) succeeded in increasing resting metabolic rate, according to a study presented last week in Berlin, Germany.

Michael Oh, M.D., a neurosurgeon at Allegheny General Hospital in Pittsburgh, Pa., presented his team’s early findings at the International Neuromodulation Society’s 11th World Congress.

According to the researchers, previous animal studies suggested that the LHA plays a vital role in regulating metabolism and can stimulate weight loss, regardless of how many calories a person consumes.

Building on this evidence, Oh and his colleagues received FDA approval to test the safety and effectiveness of deep brain stimulation (DBS) for morbidly obese patients who were 50 percent heavier than their ideal weight.

In their study, three patients who had failed to keep weight off after gastric bypass surgery received DBS implants in 2009 and 2010. In the years since they were given the implants, the patients’ metabolism rates have increased and two of the three patients have lost measurable weight.

One participant, who only lost about one percent of her body weight, commented that, for the first time in her life, she does not have to fight a constant feeling of hunger. Her binge eating score has been reduced from "severe" to within normal range.

Another patient experienced a nine percent increase in resting metabolic rate, which resulted in a weight loss of 16.4 percent. The third patient lost 12.3 percent of her weight after 11 months of DBS.

What Is Deep Brain Stimulation?

Deep brain stimulation involves implanting a device called a neurostimulator, which delivers tiny electrical signals to specific areas of the brain. DBS is routinely used to control the symptoms of movement disorders, such as Parkinson’s disease and dystonia.

In DBS, slender leads tipped by a row of electrical contacts deliver mild electric pulses to the brain. The leads are connected to a compact, battery-operated pulse generator, similar to a heart pacemaker.

The goal of electrical brain stimulation is to rebalance the brain's neural circuits by influencing when nerves fire and neurotransmitter chemicals are released.

According to the National Institutes of Health, deep brain stimulation is a well-tolerated procedure that is both individually programmable and reversible. However, potential risks include infection, bleeding in the brain, and an allergic reaction to the device components.

Working with collaborators at Pennington Metabolic Center in Baton Rouge, La., Oh and colleagues arranged for the trial patients to undergo detailed metabolic studies over the course of three days.

The patients rested comfortably in enclosed metabolic chambers where their oxygen consumption and carbon dioxide release were analyzed. Each patient’s normal resting metabolism was measured and tested against a range of neurostimulation settings.

Based on the results, the researchers chose a DBS setting that would have the greatest effect on raising each patient’s resting metabolic rate. “The metabolic studies proved useful to guide optimal settings (of neurostimulation),” Oh said in a press release.

The scientists found no negative effects of DBS on the patients' psychological or mental function.

What’s Next?

Oh and his team will continue to monitor the effects of hypothalamic deep brain stimulation on these three patients to see whether the positive impact on metabolic rate lasts over time.

According to Oh, humans evolved to automatically lower their metabolism when their food intake goes down. This innate metabolic “set point” is the reason that weight-loss can be challenging for many patients.

This study suggests that the “set point” can be adjusted, like a thermostat, in order to reduce a person's appetite and food cravings.

However, if DBS is one day approved for obesity, it would likely be used only as a treatment of last resort if diet and bariatric surgery have failed, according to the researchers.

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