In some of the more than 500 Alzheimer’s-related presentations at SfN, researchers shed new light on how diet, exercise, red wine consumption, and stress may lower or raise disease risk.
Findings from one study suggest why people who have high cholesterol are at higher risk of developing Alzheimer’s disease. Narayan Bhat of the neurosciences department at the Medical University of South Carolina in Charleston and colleagues found that excess cholesterol in the diet of mice triggered both physical changes in the brain and memory problems.
During the study, the researchers fed one group of mice a high-fat, high-cholesterol diet and the other group their normal, healthy chow. After two months, they tested the animals in a task that required them to remember which parts of a maze they had visited before.
Early in the experiment, when they had only a few previously visited spots to remember, all of the animals did equally well. But as the task became more difficult and the animals needed to remember more information, the mice on the unhealthy diet made more mistakes.
“These were big differences in behavior,” Bhat said. The fact that the animals’ performance worsened only as the difficulty of the memory task increased suggests that the high-cholesterol diet impaired the animals’ working memory, which temporarily stores information we need to complete a task and is lost early in Alzheimer’s disease.
Moreover, when Bhat’s team looked at the animals’ brain tissue, they found an increase in biochemical markers of inflammation relative to the control animals, as well as an increase in the number of activated immune cells. Given these changes in the brain tissue, the scientists think the extra cholesterol causes physical damage to the neurons or the blood vessels that run through the brain.