“We know that many lifestyle diseases related to obesity, including type 2 diabetes, increase the risk of dementia. The thesis supports the hypothesis that the stress hormone cortisol could be a link between obesity, type 2 diabetes and a change in brain function. The results also indicate an improvement in the metabolism of cortisol and the brain’s function after lifestyle changes,” says Andreas Stomby, doctoral student at the Department of Public Health and Clinical Medicine at Umeå University.
The thesis contains four studies where Andreas Stomby, among others, has performed structural MRI on both men and women, who also underwent memory tests and analyses of their cortisol levels. He also examined how the brain’s activation pattern during memory testing and cortisol metabolism are affected by a Palaeolithic diet or a diet following the Nordic nutrition recommendations. He also studied what effect training can have on memory and brain activation in patients with type 2 diabetes.
Andreas Stomby states that weight loss in obese persons with or without type 2 diabetes can lead to increased activity in the areas of the brain that are important for memory performance. Weight loss can also lead to a normalisation of the metabolism of the stress hormone cortisol, which has previously been shown to be connected to obesity and type 2 diabetes. The effects were similar after following a Palaeolithic diet or a diet following the Nordic nutrition recommendations. Andreas Stomby found no other effects on intense cardiovascular training.
Furthermore, the results show that high levels of cortisol are related to structural changes in the prefrontal brain structure as well as a connection between high levels of cortisol and reduced long-term memory in patients with type 2 diabetes.
“This could indicate that a reduced exposure to the stress hormone could be a link between lifestyle changes and positive effects on the brain’s structure and function. Whether these changes can have positive effects on the memory function over time, and hence reduce the risk of contracting dementia, should be examined further in future studies,” says Andreas Stomby.
Andreas Stomby grew up in Jönköping, Sweden. He is a medical doctor and doctoral student at the Department of Public Health and Clinical Medicine, Umeå University.
For more information, please contact:
Andreas Stomby, doctoral student, Department of Public Health and Clinical Medicine
Phone: +46 73 959 51 29
Facts about the studies
Andreas Stomby’s research is performed in four parts, one of which was a population-based study involving 200 middle-aged or older women and men. They were examined with functional magnetic resonance imaging (fMRI), memory tests and analyses of cortisol levels. The remaining three studies were based on lifestyle interventions.
In one intervention a Palaeolithic diet was compared to a diet following the Nordic nutrition recommendations for two years. The metabolism of the steroid hormone cortisol was examined in 50 participants. On top of that, 20 more participants underwent memory tests and were examined with functional resonance imaging. In the other intervention a Palaeolithic diet with no training was compared to a Palaeolithic diet combined with intensive training for twelve weeks. The participants in this study all had type 2 diabetes. 30 participants were examined with memory tests and fMRI.
About the thesis defence
Wednesday 27 May Andreas Stomby, Department of Public Health and Clinical Medicine, Umeå University, his thesis entitled: “Brain function and glucocorticoids in obesity and type 2 diabetes including effects of lifestyle interventions” (Swedish title: ”Effekter av livsstilsförändring på hjärnfunktion och stresshormoner vid fetma och typ 2 diabetes”).
Opponent is Professor Alasdair MacLullich, Department of Geriatric Medicine, University of Edinburgh, United Kingdom.
Supervisor is Professor Tommy Olsson.
The defence will take place at 13:00 in Bergasalen in the University Hospital of Umeå.
Editor: Anna Lawrence