Diet Affects Markers of Alzheimer's Disease
Low-Fat, Low-Glycemic-Index Diets Improve Markers for Alzheimer’s Disease, Study Suggests
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The low-fat diet, however, decreased those levels of beta-amyloid, insulin, and F2-isoprostanes and increased levels of apolipoprotein E, suggesting a protective effect.
In adults who had already begun to have some memory and brain impairment, however, the results were more complex.
Those on the high-fat diet saw little change in the Alzheimer’s biomarkers.
“That’s possibly because they’ve already got a very pathological process going on,” Craft says, and she thinks her short study wasn’t going to make things much worse.
Those who were on the low-fat diet saw increases in the levels of beta-amyloid in their spinal fluid.
Researchers say other studies that have looked at changes in beta-amyloid as Alzheimer’s disease progresses have observed a tipping point, where levels rise until a critical level is reached and plaques begin to form. When that happens, the disease accelerates, more plaques form in the brain, and levels of beta-amyloid in spinal fluid drop.
They say the rise in beta-amyloid seen in adults with cognitive impairment on the low-fat diet may indicate that the brain is moving away from the tipping point of plaque formation and back toward a healthier, more normal state.
People with early memory loss saw other markers of oxidative damage drop on the low-fat diet, and their scores on some measures of memory improved after the study, though the changes were subtle.
Taken together, researchers say their results show that high-fat, high-sugar diets can have consequences for the brain.
“Exposing your body and your brain to this type of diet over a very long period of time is going to put you on the path to Alzheimer’s disease,” Craft says.
As tantalizing as the results, experts urge caution in the interpretation of the results.
“There are many unknowns here, such as how a person’s genetic makeup influences how their diet affects the brain, so it’s entirely possible that a low-fat diet may just help people with a certain genetic makeup," Doraiswamy says.
“There are also other dietary factors that have also been found to have possible benefit -- low-calorie diets, curcumin, Mediterranean diets rich in antioxidants, etc. Plus we need studies to see if diet plus exercises make a bigger impact,” he tells WebMD in an email. “So eventually the field will need to put these different diets to the test to see which is the best and it may turn out that there is no such thing as one diet fits all. We may have to tailor a brain-healthy lifestyle based on person's genetics and individual risks.”