High-Fat Diet Fuels Alzheimer’s Disease, Study Shows

A high-fat diet not only affects our waistlines and hearts, but can it also play a role in developing Alzheimer’s disease? A new study, conducted by Spanish researchers and published in the journal Nutrients, suggests that may very well be the case — and tiny molecules called miRNAs could be the missing link.

Alzheimer’s disease, the most common form of dementia, affects millions worldwide. It’s characterized by a progressive loss of memory and other cognitive functions. While the exact causes are still being unraveled, we know that certain factors like genetics, age, and lifestyle play a role.

For the study, scientists from the Universitat Rovira i Virgili used two groups of mice: normal mice and those genetically engineered to develop Alzheimer’s-like symptoms.

Half of each group was fed a regular diet, while the other half chowed down on a high-fat feast. As expected, the mice on the fatty diet gained weight and developed issues with glucose and insulin metabolism — hallmarks of Type 2 diabetes.

But here’s where it gets interesting. Researchers also found significant changes in the levels of certain miRNAs in these chunky mice. miRNAs are tiny molecules that help regulate gene expression. Think of them as little molecular switches that can turn genes on or off.

Specifically, they found that a miRNA called miR-19a-3p was elevated in the blood, cortex (the outer layer of the brain), and hippocampus (a key area for memory) of the Alzheimer’s mice. It was also higher in the blood and hippocampus of the normal mice on the high-fat diet. This suggests that miR-19a-3p could be a link between unhealthy eating, metabolic problems, and Alzheimer’s risk.

But miR-19a-3p wasn’t the only culprit. The high-fat diet also boosted levels of miR-34a and miR-146a in the blood of both groups of mice. Previous studies have linked these miRNAs to insulin resistance, inflammation, and even the formation of the toxic protein clumps seen in Alzheimer’s brains.

On the flip side, researchers found that a miRNA called miR-29c was higher in the blood and hippocampus of normal mice on the fatty diet. This could be an attempt by the body to fight back, as miR-29c is known to target and reduce levels of BACE1, an enzyme that helps produce toxic amyloid proteins in Alzheimer’s.

What does all this mean? Well, it suggests that a high-fat diet could alter levels of key miRNAs in the brain and body, potentially accelerating or worsening Alzheimer’s symptoms. It also highlights these tiny molecules as possible targets for new Alzheimer’s drugs or diagnostic tests.

Of course, mouse studies don’t always translate perfectly to humans. But researchers believe their findings warrant a closer look at the link between diet, metabolism, miRNAs, and dementia risk in people.

“The results of this study are a step forward in our understanding of this disease and may explain the relationship between obesity, Type 2 diabetes and the onset of Alzheimer’s. The findings also offer new targets for the possible prevention and treatment of the disease”, says study author Mònica Bulló, researcher at the Universitat Rovira i Virgili, in a media release.

In the meantime, the study serves as a reminder that what we eat doesn’t just affect our physical health – -it could impact our cognitive well-being too, especially as we age. While more research is needed, it can’t hurt to trade some of those saturated fats for brain-friendly fare like leafy greens, fatty fish, and berries.


  1. The mice put on weight.
    So maybe it’s the weight gain, not the diet.
    Compare effect of equal-calorie diet, one high fat, one low fat.

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