Obesity ages the brain faster
Being heavily overweight does not just alter the risk of developing diabetes, heart failure or arteriosclerosis, it also affects the brain and its various cognitive abilities. Scientists from the Max Planck Institute for Human Cognitive and Brain Sciences (MPI CBS) in Leipzig have discovered that in older obese people the so-called Default Mode Network is less wired and therefore processes such as remembering and planning could be impaired. This is an important indication of early impending Alzheimer’s disease.
“We’ve presumed for a long time that a higher Body Mass Index could also harm the brain. Now we have succeeded in finding direct indications for this assumption”, says Veronica Witte, head of the underlying study and of the research group Aging and Obesity at from Max Planck Institute for Human Cognitive and Brain Sciences (MPI CBS). “We observed that in obese people some regions in the Default Mode Network, or DMN for short, are less wired, therefore compromising cooperation between single regions.”
On the one hand, the DMN becomes active when we focus our attention on our inner constitution, let our thoughts run free or when we remember something. On the other hand, it supports those tasks that precede or accompany an action, such as targeted planning, coordinating, taking obstacles into account or controlling our impulses.
The daunting fact is that a less wired DMN is also an early signal of a higher risk of Alzheimer’s disease. Indications that otherwise emerge at an older age or when facing dementia are visible earlier in obese people.
Until now, it was unclear whether the opposite could be the case: that obesity in older age could offer certain protection against Alzheimer’s disease—for instance the mortality after a stroke or in some age-related diseases is lower for obese people”, explains the neuroscientist. “In our case this phenomenon known as obesity paradox didn’t occur. Obesity seems to age the brain faster, therefore raising the risk of developing Alzheimer’s disease.”
Previous studies investigating the connection between obesity and brain structure were mainly carried out in fewer and younger participants, leading to contradictory results. The relations were therefore not directly applicable for older obese people. In contrast to this, the current study, in cooperation with Leipzig Research Center for Civilisation Diseases (LIFE), examined more than 700 healthy individuals ranging from 60 to 80 years of age without any history of stroke. The results found by the MPI CBS neuroscientists, in which risk factors like smoking, depression and high blood pressure were also included, could therefore be interpreted as especially significant.
However, these findings are just snapshots. “It would be interesting to observe in further studies how the DMN develops over the years and which effects it has on various cognitive abilities. Or how it would change, for instance, if the participants were to radically change their lifestyle and reduce their body weight”, Witte adds.