Thesis defense Debby Vreeken (Donders Series 612)

15 June 2023

Promotors: prof. dr. Amanda J. Kiliaan and prof. dr. Eric J. Hazebroek.
Copromotors: dr. Maximilian Wiesmann

Obesity and the brain. Improving the brain by losing weight?

Obesity is a major public health concern worldwide and its prevalence is still growing. It is well known that obesity leads to an increased risk of developing metabolic syndrome and there is accumulating evidence that obesity negatively affects brain function and structure. The exact mechanisms how obesity may affect brain health are not well established, but proposed mechanisms include the role of white adipose tissue. The aim of this thesis was to understand the effect of obesity and weight loss after bariatric surgery on brain function and structure involving white adipose tissue, adipokines and inflammation. Our research showed that white adipose tissue may play a role in the link between obesity and the brain. More specifically, omental white adipose tissue health was related to cerebrovascular health in subjects with severe obesity. After gastric bypass surgery, 40% of the patients showed cognitive improvement. Reduced inflammation and changes in hormones produced in white adipose tissue seem to play a role in this. Additionally, we explored whether cognitive control, measured with the Stroop task may act as a predictor for weight loss after bariatric surgery. However, no indications could be shown that cognitive control can serve as a predictor for weight loss, which suggests a far more complex mechanism underlying weight loss, as not only cognitive control can contribute to weight loss, but also genetic factors, hormones, age and diet. The main conclusions of this thesis are: there is a clear link between obesity and the brain, weight loss after bariatric surgery is often associated with cognitive improvement and the link between obesity and the brain is far more complex than the role of white adipose tissue and adipokines alone. In the end, we believe this thesis has expanded the knowledge on the impact of obesity and weight loss on brain function and structure which might help to develop better healthcare as well as possible preventives against obesity and associated disorders.