Obesity Impairs Brain Circulation

Obesity has been found to cause poor blood circulation in the brain, regardless of age. This almost linear relationship affects regions responsible for memory and learning, which could explain why overweight individuals are more prone to Alzheimer’s disease. A recent study by the University College London has shown that obesity increases the risk of dementia by up to 30%. Additionally, science has already demonstrated that obesity damages the white matter of the brain in teenagers. However, the processes responsible for this damage have not been investigated. Researchers at the Amen Clinic in California have now published a study in the Journal of Alzheimer’s Disease, which examined the brain circulation of 17,000 men and women. The data was collected using Single Photon Emission Computed Tomography (SPECT), a method in which a slightly radioactive contrast agent is administered to the subjects, allowing the distribution in the brain to be observed through emitted gamma radiation. The repeated scans were performed both at rest and during a concentration task to document which brain areas were supplied with blood and to what extent. The scientists discovered an almost linear relationship between brain circulation and Body Mass Index (BMI). Specifically, the circulation of important areas of the brain decreases as a person’s weight increases. This occurs both at rest and during mental tasks and is observable even with mild obesity. According to Amen, “this is particularly evident in brain areas that are susceptible to Alzheimer’s disease.” These include the hippocampus, which is important for memory, the gyrus cinguli, which is important for learning and memory, and the temporal and parietal lobes. In all subjects, the circulation of these areas decreased with increasing BMI, regardless of age. Insufficient circulation accelerates the long-term degradation of brain tissue and leads to functional impairments. The researchers therefore conclude that “the results could provide a possible physiological explanation for why obesity is a risk factor for Alzheimer’s disease.” Further studies will investigate whether, in addition to circulation, chronic inflammatory processes also damage the brain alongside obesity.