Your Gut Microbiome May Play a Role in Alzheimer’s Risk: What an MD Wants You To Know

One of the most frustrating things about Alzheimer’s , a devastating brain disease that slowly destroys memory and thinking skills, is that by the time symptoms appear, it’s too late to stop it. That could change, thanks to a new study in the journal Brain . Researchers found that the gut microbiome — the ecosystem of microorganisms living in our GI tract — may play a role in Alzheimer’s disease. And more importantly, it may help predict how long before symptoms take hold in the brain.

“Alzheimer’s doesn’t start when you begin losing memory ,” explains gastroenterologist and neurobiologist Emeran A. Mayer, MD , Distinguished Research Professor of Medicine at the David Geffen School of Medicine at UCLA and author of The Mind-Gut Connection . “If microbiome biomarkers can identify red flags for Alzheimer’s, that would be a huge thing. It means we could do tests on people in middle age who have no symptoms.”

“If you could catch the signs of Alzheimer’s early,” he adds, “when changes are just present in the gut but not yet in the brain, the potential for cure would be much higher.”

The connection between the gut microbiome and Alzheimer’s

In the study, scientists used fecal transplants to transfer gut bacteria from people with Alzheimer’s disease into young, healthy rats whose own microbiomes had been greatly suppressed with antibiotics. Soon, the rodents started showing signs of dementia. Symptoms included impaired spatial memory and cognitive function, reflecting the abnormal gut microbes from the Alzheimer’s patients.

But how much of what happens in animals aligns with what actually happens in humans? “Behaviors that we both have — cognitive deficits in orientation and memory — suggest that we’re looking at the same read-out, but we can’t prove it,” Dr. Mayer says.

But these researchers took their findings to a human level. How? They looked at cells in the hippocampus, the part of the brain where memories form. “One of the factors that plays a big role in Alzheimer’s disease is hippocampal neurogenesis,” or the ability of nerve cells in this brain region to regenerate, Dr. Mayer notes. The research team found that neurogenesis was compromised in both the rats that received transplants and in the human hippocampal cells. “This goes further than just rat behavior,” he adds.

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Why the link between the gut microbiome and Alzheimer’s matters

This study adds to evidence that the microbiome plays a “significant role” in Alzheimer’s disease, according to Dr. Mayer. “This is not surprising, as the microbiome is the interface between the world around us and our immune system,” he says.

Other research in Frontiers in Immunology has shown that inflammation, partly coming from the gut bacteria, can lead to and worsen Alzheimer’s progression. At the same time, research in one medical journal shows that certain anti-inflammatory diets, including the MIND diet (a blend of the Mediterranean Diet and the DASH diet), can protect against cognitive decline.

All this evidence strongly suggests that our microbiome, and by extension, our diet, has a role to play in preventing dementia. “What percentage it contributes to Alzheimer’s disease — in addition to other factors including genes, infectious causes, viruses and antibodies — we don’t yet know,” Dr. Mayer says. “But this study clearly supports it as an important factor.”

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How to boost gut health to prevent Alzheimer’s

There are certainly foods thought to cultivate a healthy gut microbiome and promote a diversity and richness of bacteria. The greater the variety, the better. But when it comes to preventing Alzheimer’s, the general recommendation is to live a healthy lifestyle.

According to Dr. Mayer, that means eating a 70% plant-based diet, like the Mediterranean Diet, getting regular physical exercise, having good sleep hygiene and maintaining a healthy mental state with meditation, mindfulness or other intentional relaxation. “If you take five of these factors and start them in middle age, not at 70 or 80, my bet is that there will be a significant reduction of Alzheimer’s disease later in life,” Dr. Mayer says.

And there’s no need to do crossword puzzles (unless you want to!), but do take care of your mental health. “I would not underestimate psychosocial factors such as social isolation, stress and chronic depression, all of which have been increasing dramatically,” Dr. Mayer notes.

The good news is that although scientists haven’t yet cracked the code to Alzheimer’s disease, there are steps you can take to lower your odds. “If you change your lifestyle and switch to a healthy diet along with these other lifestyle factors, getting older does not have to mean developing cognitive decline,” Dr. Mayer says.

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This content is not a substitute for professional medical advice or diagnosis. Always consult your physician before pursuing any treatment plan .