Neuromodulation for Eating Control in Women
Professor, University of São Paulo
Prof. Priscila Giacomo Fassini is a dietitian with research experience and professional practice focused on clinical nutrition. After completing her PhD and working with human energy metabolism, Prof. Priscila Giacomo Fassini is now working on evaluating the efficacy of non-invasive brain stimulation to improve eating control in women with obesity.
Why Do We Need New Solutions to The Obesity Pandemic?
I have been working on evaluating the efficacy of tDCS, transcranial Direct Current Stimulation, which is non-invasive neuromodulation, to improve eating control in women with obesity. We know that obesity is a very complex and multifactorial disease and the prevalence of obesity is increasing at alarming rates in many countries.
The epidemic of obesity is now recognized as one of the most critical public health problems facing the world today. The most widely recommended therapy for obesity is lifestyle modification, which includes diet and exercise. It sounds easy, but it is not, implementing change that can lead to weight loss is difficult. On top of that, maintaining a long-term weight loss is even more challenging. More than 80% of people who start a diet regain the initial weight loss or even more.
Neuromodulation as a Treatment for Obesity
We are talking about a very complex and important disease that is also a pandemic. You need to have academic effort to try and understand it better and figure out new ways of treatment. The control of food intake is also highly complex, involving neuronal, hormonal and nutritional control. Individuals with obesity show a decreased activity in the prefrontal cortex, a key brain region supporting eating behaviour regulation.
Recent evidence in the field of obesity and brain-based integration indicates a potential for designing new therapeutic strategies of intervention because we needed to try and find new ways of treating these diseases. In this context, non-invasive neuromodulation of brain activity has been shown in the literature to be a technique that could help reduce food intake, appetite, and food craving, that also can lead to the reduction of body weight. Therefore, tDCS targeting the dorsal lateral prefrontal cortex could reverse these abnormalities and may be a potential benefit for people who are trying to lose weight, because it modifies the cortical with stability and may facilitate an improvement of eating control.
However, we have limited studies in the literature, and most of them are short-term studies that present a very high variability between individuals.
Dorsolateral Prefrontal Cortex as a Neuromodulation Target for Obesity Treatment
The target area of the brain that we are looking at stimulating is related to cognitive control. We know that people with obesity have impairment of this function. It’s not because they don’t want to follow a diet or do not understand it, it’s because they have real difficulty related to impairment in the brain network, leading them to have poor cognitive control. When we look at the brain of obese people compared to lean individuals, we can see this difference of activity in this area of the brain.
So we thought that maybe if we try to reverse these abnormalities we could help these patients to have more control of their food choice, and perhaps this could help them to lose weight. That was our hypothesis. However, the actual mechanisms behind all that are still unclear because brains are very complex, so we still need to learn a lot. Most of the studies published are focused on the left or the right side of the dorsolateral prefrontal cortex.
Why haven’t we developed a drug to treat obesity?
There are options of pharmacological treatments and also surgeries, which isn’t right for everyone because they are very subjective. However, we have seen some studies associating tDCS with other strategies. I think that would be the future of the field, associating tDCS with a hypocaloric diet, as we did in our study, or with medications and pharmacological therapies if we take depression as an example. So we need to not just look at tDCS alone, but also in association with other therapies to see if they could improve the therapy we are aiming for.
Does tDCS Work for Everyone?
We studied just this genetic polymorphism, but we know that other genetic factors can affect eating behaviour that we also need to explore and try to understand better. I think this is the first study that showed the response to the high variability between individuals and helps us understand why some people respond to tDCS intervention and others don’t. This is what we see in the literature, but we do not understand why. So why it may benefit some individuals but not all. I think that we need to start looking at the genotype and are other factors that are also involved in eating behaviour control.
There are other neurotransmitters here; we are talking mostly about dopamine, but other catecholamines are also involved in eating behaviour control. Eating behaviour is very complex; it involves the integration of homeostatic and known homeostatic regulatory pathways. In research, we study both mechanisms but we are not integrating all these mechanisms together.
We need to look at this integration to better understand this complexity and give answers to who can benefit from this intervention. Because as in any therapy, we see that it might not be good for everybody. For example, one diet can be good for one person and can be harmful to another, it depends on the individual level. We need to start looking at the individual level to answer who can benefit from tDCS.
Can Neuromodulation Work in Undereating & in Overeating?
There are already a few studies published on anorexia and bulimia showing good results. Food control is also related with impairments of behaviour, so we have an analysis of anorexia using TMS shown potentially positive results and also of bulimia working with tDCS.