The appendix has long been dismissed as a largely vestigial organ, but it may actually play an important role in maintaining brain health and protecting against cognitive decline.
A study found that removing the appendix is linked to Alzheimer’s disease. Appendectomy stood out as the strongest single contributor to Alzheimer’s risk, outweighing other lifestyle and medical history factors.
“We speculate that it functions as a reservoir of beneficial gut bacteria,” Kaveh Khalilpour, co-lead of the research and an associate professor at the University of Technology Sydney, said in a statement. “When it is removed, the microbiome loses a key recovery mechanism, its ability to replenish healthy microbial communities after illness, infection, or antibiotic use.”
The study, published in Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring, found that everyday health information—particularly diet and medical history—could help identify patterns linked to Alzheimer’s risk.
Unlike genetic risk, these factors may be modifiable, Faezeh Karimi, a senior lecturer at the University of Technology Sydney, told The Epoch Times via email.
If confirmed in future research, the results could contribute to simpler, lower-cost ways to flag Alzheimer’s risk earlier.
Which Health Factors Stood Out
In an analysis of nearly 10,000 people, researchers found that answers to basic health questionnaires could distinguish people with Alzheimer’s from those without it with fairly strong accuracy.
The researchers used machine learning to analyze 120 different variables across 9,832 people, including diet, sleep, vitamin intake, medical history, and general lifestyle factors.
Some of the strongest signals in the model came from unexpected places.
People who had their appendix removed—one of the most common surgical procedures—showed a much higher likelihood of having Alzheimer’s risk in the model. The researchers suggest that the appendix acts as a reservoir for beneficial gut bacteria, helping the microbiome recover after illness, infection, or antibiotic use. When it is removed, recovery capacity is reduced, making it harder for healthy microbial communities to re-establish themselves.
Beyond this surprising finding, medical history and diet stood out as the strongest predictors of risk. Common long-term health conditions such as diabetes, high blood pressure, and depression were among the strongest signals.
Diet performed best overall. Rather than any single food or nutrient driving the results, long-term eating habits mattered most, with dairy and other sources of lactose appearing particularly protective. Diets rich in whole foods, plant protein, and omega-3 fatty acids were also linked to lower Alzheimer’s risk, while processed foods, refined sugars, and saturated fats were associated with higher risk.
Together, the findings point to Alzheimer’s risk as the accumulation of many small factors over time, Karimi noted.
“Our study adds to growing evidence that taking care of gut health through healthy eating, managing chronic disease, and reducing inflammation may be one important part of lowering long-term risk,” Khalilpour said.
The Gut-Brain Connection
The researchers also examined the gut-brain axis—a two-way communication system linking the digestive and immune systems to the brain.
“When we see gut-related patterns linked to Alzheimer’s risk, we believe they may be acting like an early warning signal, showing us how broader health and lifestyle factors are affecting the brain over time,” Khalilpour said.
In a smaller, exploratory analysis of gut microbiome data from about 2,000 samples, people with Alzheimer’s showed signs consistent with dysbiosis, or an imbalance in gut bacteria. This included lower microbial diversity and significantly reduced levels of beneficial bacteria such as Roseburia and Faecalibacterium—species that produce short-chain fatty acids, substances that help control inflammation in the body.
“Microbial diversity was reduced, and a more inflammatory microbial environment had taken hold, one that appears capable of sending damaging signals to the brain via the gut-brain axis,” Karimi said.
When functioning well, a healthy gut supports the immune system and keeps brain inflammation in check. “The gut helps regulate inflammation, supports the immune system, and produces important chemicals that affect how the brain functions,” Khalilpour said.
These signals don’t exist in isolation, he added. Gut health reflects many aspects of daily life working together over time.
Looking Ahead: A New Path for Screening
While the model is not a diagnostic tool, the researchers said it points to a future in which simple health questionnaires could help flag patterns of risk earlier and at lower cost.
“Unlike genetic risk factors, these exist on a timeline that may be intervened upon,” Karimi said. That makes them potentially actionable. Over time, she said, it may become possible not only to identify risk earlier, but to intervene before disease processes are fully established.
“The goal is not just to build smarter prediction tools, but to build better public health systems that can identify risk earlier, guide prevention strategies, and support healthier aging at a population level,” Khalilpour said.