Brain works better after bariatric surgery Study shows positive effect of weight loss on brain performance

Bariatric surgery not only leads to weight loss, but has also a positive effect on the brain. In a study exerted by the Radboud University Medical Center and Rijnstate Hospital in collaboration with TNO Leiden, nearly half of the participants scored significantly better on a variety of brain tests six months after surgery. 

The most striking finding of a large study on the effects of gastric bypass surgery is that nearly 45% of study participants scored significantly better on brain tests six months after surgery. Their test results improved by more than twenty percent after bariatric surgery. The other participants were stable or improved slightly. Furthermore, participants had lower blood pressure, less diabetes, lower cholesterol, fewer depressive symptoms, and their medication use went down.

On average, participants lost 60 pounds in six months. How that weight loss leads to better brain performance is not yet entirely clear. ‘We think this is caused by a combination of factors’, says PhD student Debby Vreeken of the Radboudumc, who will defend her thesis on June 15. 'Fat cells release more than a hundred signaling molecules, that cause inflammation and negatively affect blood vessels, including in the brain. Those substances decrease with weight loss. But we also see that after a gastric bypass, people start to exercise more, which improves blood flow.'

'It is precisely this combination of inflammation and reduced blood supply that underlies many brain disorders, such as dementia’, adds Professor of Anatomy Amanda Kiliaan. She and her group are investigating risk factors for these diseases of the small vessels, including high blood pressure. 'Obesity is an important risk factor. Participants in our study are still young and in the early stages of damage to the small vessels. That's why it's so interesting to study this group. Now we see that the brain performs better by losing weight and the process of damage is apparently partly reversible.'

Brain function

In their study, the researchers show that there is a difference between abdominal fat and subcutaneous fat. Abdominal fat that surrounds organs has long been labeled ‘dangerous fat’. Kiliaan and Vreeken observe this as well. They show an association between the size and quantity of fat cells in abdominal fat and the quality of blood vessels in the brain. They do not see that in subcutaneous fat. Thus, the loss of abdominal fat in particular seems to be important for brain function.

The conclusions are based on a study of 146 people who underwent gastric bypass surgery. The average age was 46 years. The researchers followed the participants for two years. They made MRI scans of the brain, collected blood and stool samples, and took small pieces of fatty tissue, liver and intestine during surgery. They also studied brain performance, with tests for concentration, memory and verbal fluency before and after bariatric surgery.

Despite the positive effects, gastric bypass surgery is not just a jubilant story and, as with any surgery, it comes with risks. People lose a lot of weight after gastric bypass surgery, but many patients regain some weight after one or two years. In addition, stomach reduction sometimes leads to unexplained abdominal pain and it changes the composition of bacteria in the gut. The latter is an important topic for follow-up research by Kiliaan and her team in collaboration with TNO and Rijnstate Hospital.

About the publications

These results from the BARICO study were published in:
- Jama Open Network: Factors Associated With Cognitive Improvement After Bariatric Surgery Among Patients With Severe Obesity in the Netherlands. Debby Vreeken, Florine Seidel, Emma M. Custers, Lisette Olsthoorn, Sophie Cools, Edo O. Aarts, Robert Kleemann, Roy P.C. Kessels, Maximilian Wiesmann, Eric J. Hazebroek, Amanda J. Kiliaan.
- Neurology: Impact of White Adipose Tissue on Brain Structure, Perfusion, and Cognitive Function in Patients With Severe Obesity The BARICO Study. Debby Vreeken, Florine Seidel, Guido de La Roij, Wouter Vening, Willem A. den Hengst, Lars Verschuren, Serdar Ozsezen, Roy P.C. Kessels, Marco Duering, Henk J.M.M. Mutsaerts, Robert Kleemann, Maximilian Wiesmann, Eric J. Hazebroek, Amanda J. Kiliaan.

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