04:05pm Tuesday 14 July 2020

Significant Weight Loss Following Vagus Nerve Stimulation

Thirty percent less food intake and significant weight loss – these are the findings of research conducted at the Sahlgrenska Academy that saw laboratory animals receiving so-called vagus nerve stimulation. The research has also given us a better idea of the effect the method has on the body.

“In the long term, this could definitely be an alternative for patients who are overweight who perhaps cannot, or do not wish to, undergo a gastric bypass, or other types of weight reduction surgeries” says David Fröjd Révész, a postdoctoral researcher in clinical neuroscience and specialist neuroscience doctor.

Vagus nerve stimulation is a well-established way of treating epilepsy in patients who do not respond well enough to other treatments. It consists of a pacemaker-like stimulator implanted to provide electric stimuli to the vagus nerve via electrodes that are wrapped around the nerve. These weak, frequent electric shocks can both reduce and decrease the length of attacks.

The method is also used to treat depression, or at least has been trialed for such in Sweden, with the research now also indicating it is an effective treatment for excess weight. The vagus nerve itself sends signals from (in principle) all parts of the body’s internal organs to the brain stem, with impulses then distributed from there to the entire brain via various switching stations.

New Brain Cells

“The rats in the trial ate the same number of meals, but less food. The stimulation they received made them feel full sooner, partly because their brains were stimulated, and partly because signals from the brain to the intestine were blocked,” says David Fröjd Révész.

The animals lost ten percent of their weight after one week, and after six to eight weeks were eating 30 percent less than to start with. In another trial, the stimulation also led to many new brain cells being born, which is one possible explanation for the positive effects vagus nerve stimulation can have on depression.

“It’s a bit like an electric shock treatment, although much milder, releasing signal substances and having an anti-depressive effect,” says David Fröjd Révész.

Sahlgrenska University Hospital in Gothenburg was one of the first hospitals in the world to implant vagus nerve stimulators in patients with epilepsy that did not respond to medication in the early 1990s. David Fröjd Révész’s research also includes register studies on the same patients, who totaled 247 in number.

Safe Method

The results indicated that the number of epileptic seizures halved in around 40 percent of the patients on whom medication had previous had insufficient effect. The electric shocks can affect people’s vocal cords and voices, but usually only temporarily. The risks associated with the operation and follow-up treatment proved low otherwise. The research looked at a 25-year period.

“We looked at the safety of the treatment over a very long period, whereas most other studies did so for a maximum of five years. We now know about the full spectrum of potential side effects of the surgery, including the battery changes that need to be done periodically and always pose a certain risk of infection,” says David Fröjd Révész.

He believes that the findings could lead to vagus nerve stimulation treatment becoming more widespread in the future, and being used more frequently to combat depression and excess weight.

“It is important that we find and use alternative ways of treating these widespread diseases. They can cause tremendous suffering among both patients and their family members and, because of the drug prescriptions, hospital stays and long absences from work, are also very costly for society,” David Fröjd Révész points out.

Link to dissertation. Head researcher: David Fröjd Révész.


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