A noninvasive technique called deep transcranial magnetic stimulation (dTMS) can help to manage cravings and overeating, studies have found. Now, Italian researchers have found that it improves the composition of the gut bacteria, thought to be involved in obesity, and also produces weight loss.1
The team reported the findings at ENDO 2017, the annual meeting of the Endocrine Society, in Orlando. "The major finding of this study I presented at this meeting is preliminary evidence that repetitive dTMS may act also on modifying the gut microbiota," says Livio Luzi, MD, a professor at the University of Milan.
The technique does not require implanting electrodes as another technique, deep brain stimulation, does. Instead, an electromagnetic coil, placed on the scalp, sends magnetic pulses that stimulate deep, specific brain regions. "It's quite noisy, like an MRI," Dr. Luzi says. He advises patients to wear earplugs.
In the U.S., dTMS has only one official approved use. The FDA ok'd it in 2008 to treat medication-resistant major depression. Elsewhere, researchers also use the technique for other conditions, including addictions to smoking, alcohol, drugs and gambling, Dr. Luzi says.2
In the new study, Dr. Luzi assigned 14 obese men and women, with an average body mass index (BMI) of more than 38, to get either the dTMS or a sham treatment that looked the same. Their average age was 45. All the participants had 3 sessions a week for 5 weeks. Before and after the 5 weeks, everyone gave stool samples so the researchers could determine if their gut bacteria changed.1
The researchers also measured blood levels of insulin, glucose, pituitary hormones (which play a role in regulating appetite) and neurotransmitters such as norepinephrine (which can affect gut bacteria).
The dTMS group ''lost 3% of their body weight in five weeks," says Dr. Luzi, significantly more than the comparison group. "We saw declines in blood glucose and in insulin," he says of the treated group. The treated group had reductions in norepinephrine levels. All the participants followed exactly the same diet, he says, so ''it's not a dietary effect." In the treated group, the ''good'' bacteria in the gut increased while the ''bad'' bacteria decreased. There were no substantial changes in the gut bacteria in the comparison group.
Experts know that an unhealthy gut microbiota can change the brain's signal for appetite and feeling full, Dr. Luzi says. And, he says, an underlying cause of obesity may be this impaired gut bacteria environment, an imbalance in the mix of beneficial and harmful microorganisms that live in everyone's digestive tract.
The improvements in the gut bacteria correlated with improvements with glucose, insulin and other measures, he found. The results are preliminary, Dr. Luzi says. However, if the data are confirmed in other studies, he says it would strongly suggest that the long-lasting effects of stimulation are at least partly due to the modification of the gut microbiota to a more normal pattern.1
The new study advances the field, says J. Michael Gonzalez-Campoy, MD, PhD, FACE, medical director and CEO of the Minnesota Center for Obesity, Metabolism and Endocrinology and a member of the editorial board for EndocrineWeb.
"It is now well-established that obesity is associated with a change of the gut microbiome," he says. "It is also well established that the deep centers of the brain including the hypothalamus, are major regulators of food intake," Dr. Gonzalez-Campoy says. Scientists talk about a two-way gut-brain axis as an area of interest in regulating emery balance and fat stores, he says. "In particular, there is active nerve and hormone signaling form the gut to the brain. And the brain then directs the gut."
The dTMS intervention ''changes the signals arriving at the hypothalamus, which is the major regulator of food intake,'' he says. The dTMS is now documented to cause weight loss, he says, and in association with this weight loss, the Italian team has documented changes in the colon bacteria linked with it.
However, more questions need to be answered, Dr. Gonzalez-Campoy says, and additional study is needed. "Although there is an association between deep transcranial magnetic stimulation, weight loss and changes in the gut microbiome, we are missing the mechanisms behind these associations."
Other questions, he says: Can the intervention be continued beyond five weeks? And is it safe long-term?
While the treated group lost 3% of their body weight in a short time, the standard or benchmark for an effective intervention is a loss of 5 to 10% of body weight over 6 to 12 months, Dr. Gonzalez-Campoy says.