It’s Time for Neurosurgeons to Take a Crack at Obesity
For decades, most interventions for obesity have failed. Innovative neurosurgical interventions of the future may just provide sustainable and significant results.
It is no secret that obesity is a national epidemic. According to the Centers for Disease Control and Prevention, the prevalence of obesity has risen to 39.8 percent in 2015-2016, affecting over 90 million Americans. The connection between obesity and the leading causes of preventable, premature death such as heart disease, stroke, type 2 diabetes and even some types of cancer are well-established.1 Traditionally, blame for the steady rise in obesity rates falls on the “big two” sources: an increasingly sedentary lifestyle and the ubiquity of inexpensive, high-caloric food items.2
Despite our firm understanding of the problem, we are no better at treating obesity or solving the underlying issues than we were several decades ago. Fad diets, weight-loss books and exercise routines are multi-billion dollar industries. You cannot turn on the TV or read a magazine without coming across something targeted at treating obesity; however, to date nothing has put a dent in the obesity numbers. Primary care physicians are inundated with obesity-related issues, yet the gold standard in their armamentarium, lifestyle changes including diet and exercise, have exceedingly high failure rates. Aggressive treatment of severe obesity with gastric bypass, gastric banding and sleeve gastrectomy comes with significant morbidity and can also demonstrate considerable failure rates.3 As everything else has come up short, it may be time to try a different avenue of treatment.
Conventional Versus Innovative Thinking
Conventionally, obesity is seen as a disease of energy imbalance:
Energy intake > Energy expenditure
Energy intake comes from the food we eat and the diet we ascribe to, but energy expenditure is much more complicated. Expenditure is a complex formula consisting of:
- Physical activity;
- Non-exercise thermogenesis; and
- Resting metabolic rate.
The last represents the largest portion of energy expenditure.4 Resting metabolic rate is influenced by a variety of factors, but the central nervous system maintains significant control over it. While it is an overly simplistic metaphor, the brain often acts as a central “thermostat,” able to change how much energy the body is burning at a given time. Only small changes in resting metabolic rate over time can lead to long-term changes in weight. Additionally, it is important not to overlook the hedonistic components of energy intake, whereas in obesity there is often a motivational, reward-seeking component to food intake.5
If there was some way to change the setting on the brain’s “thermostat” in order to even slightly raise metabolic rate, this could be a successful treatment option for obesity. Additionally, if there was some way to stop food-seeking behavior well before it leads to eating, this could also potentially have success in curbing morbid weight gain. This is precisely what several neurosurgeons around the world are currently investigating. Over the last decade, multiple neurosurgery centers have begun to explore deep brain stimulation (DBS) or responsive neurostimulation (RNS) for the treatment of obesity. Both DBS and RNS involve the placement of a neurostimulator, which sends electrical impulses into an electrode placed in a highly specific target in the brain. In this case, the goal would be to use electrical stimulation to modulate the brain’s behavior and either turn up the brain’s “thermostat” or turn down the brain’s drive to eat. Different centers have explored diverse targets, with most progress seen in the nucleus accumbens, lateral hypothalamus and ventromedial hypothalamus.
Animal and human studies are still in the early stages, but the results have been promising:6
- Phase 1 safety trial of lateral hypothalamus DBS in three patients with morbid obesity demonstrated no serious adverse effects and a trend toward weight loss in two out of the three patients.7
- An open-label trial examining DBS of the ventromedial hypothalamus in six obese patients is currently planned.8
- Many additional studies are planned going forward examining different targets and mechanisms of treatment.
As obesity has become an overwhelming national health crisis, and with minimal success with our other treatment strategies thus far, it is certainly time to explore new, innovative treatments. Hopefully, one or many of the targets currently being studied will develop into a viable neurosurgical treatment option.
It is a time when neurosurgical interventions for obesity have dropped its prevalence below 10 percent. Heart disease, diabetes, cancer rates have all plummeted. The cost of health care has dropped precipitously. The secret to French Women Don’t Get Fat will now be universally available.
That is progress we can all dream about.
2. Mcallister, E. J., Dhurandhar, N. V., Keith, S. W., Aronne, L. J., Barger, J., Baskin, M., . . . Allison, D. B. (2009). Ten Putative Contributors to the Obesity Epidemic. Critical Reviews in Food Science and Nutrition, 49(10), 868-913.
3. Gloy, V. L., Briel, M., Bhatt, D. L., Kashyap, S. R., Schauer, P. R., Mingrone, G., . . . Nordmann, A. J. (2013). Bariatric surgery versus non-surgical treatment for obesity: A systematic review and meta-analysis of randomised controlled trials. Bmj, 347(Oct22 1).
4. Lam, Y. Y., & Ravussin, E. (2016). Indirect calorimetry: An indispensable tool to understand and predict obesity. European Journal of Clinical Nutrition, 71(3), 318-322.
5. Rui, L. (2013). Brain regulation of energy balance and body weight. Reviews in Endocrine and Metabolic Disorders, 14(4), 387-407.
6. Ho, A. L., Sussman, E. S., Zhang, M., Pendharkar, A. V., Azagury, D. E., Bohon, C., & Halpern, C. H. (2015). Deep Brain Stimulation for Obesity. Cureus.
7. Whiting, D. M., Tomycz, N. D., Bailes, J., Jonge, L. D., Lecoultre, V., Wilent, B., . . . Oh, M. Y. (2013). Lateral hypothalamic area deep brain stimulation for refractory obesity: A pilot study with preliminary data on safety, body weight, and energy metabolism. Journal of Neurosurgery, 56-63.
8. De Salles, A. A., Barbosa, D. A., Fernandes, F., Abucham, J., Nazato, D. M., Oliveira, J. D., . . . Gorgulho, A. A. (2018). An Open-Label Clinical Trial of Hypothalamic Deep Brain Stimulation for Human Morbid Obesity: BLESS Study Protocol. Neurosurgery, 83(4), 800-809.
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