Fungal Infections and Alzheimer's Disease: What Does the Research Show?

Alzheimer’s disease is the most common cause of dementia and one of the leading neurodegenerative diseases in the United States. Despite decades of research, scientists have yet to fully understand what causes the disease or why it develops in some individuals but not others.

While age, genetics, and other factors are known to influence Alzheimer’s risk, accumulating research has raised questions about whether certain infectious agents—including bacteria, viruses, and fungi—may also contribute to disease development or progression.

The Connection Between Infections and Chronic Disease

The relationship between infections and chronic disease is well established in several areas of medicine.

For example, Helicobacter pylori ( H. pylori ) is a major cause of peptic ulcers, chronic hepatitis C infection can lead to liver cancer, and Epstein-Barr virus (EBV) is associated with an increased risk of certain autoimmune diseases, including multiple sclerosis and systemic lupus erythematosus.

Researchers have also investigated associations between viral infections and neurodegenerative diseases, including whether certain infections may influence disease risk years after the initial exposure.

These findings have prompted scientists to explore whether infectious organisms could also play a role in Alzheimer’s disease.

Could Fungal Infections Be Associated With Alzheimer’s Disease?

One area of emerging research involves the possible relationship between fungal organisms and Alzheimer’s disease.

In a 2015 postmortem study published in Scientific Reports , researchers examined brain tissue from individuals with Alzheimer’s disease and reported evidence of fungal material in the brain samples they analyzed.

The researchers identified fungal proteins and other fungal components in multiple brain regions, including within neurons and blood vessels. They did not detect comparable fungal material in the control brain samples examined in that study.

The authors concluded that their findings, considered alongside other published reports, supported the possibility that fungal infection may be present in the brains of individuals with Alzheimer’s disease.

These findings are intriguing because they raise questions about whether fungal organisms could contribute to inflammation, immune responses, or other processes associated with neurodegeneration.

However, detecting fungal material in brain tissue does not establish that a fungal infection causes Alzheimer’s disease. Further research is needed to determine whether these findings represent a cause, a consequence of disease-related changes, or another association.

Could Mycotoxins Also Play a Role?

Another area of investigation involves mycotoxins—potentially harmful substances produced by certain fungi.

People may encounter mycotoxins through contaminated food or other environmental exposures. Researchers have begun investigating whether exposure to these compounds may be associated with neurological conditions.

A 2021 study published in the journal Toxins compared mycotoxin measurements in individuals with Alzheimer’s disease or Parkinson’s disease and their healthy companions. The researchers reported statistically significant differences in levels of ochratoxin A, a mycotoxin produced by certain species of Aspergillus and Penicillium fungi.

These findings raise questions about whether mycotoxin exposure could be relevant to neurological health. However, differences in measured toxin levels do not establish that mycotoxins caused the diseases studied. Additional research is necessary to clarify the relationship, including whether exposure precedes disease onset and whether reducing exposure affects clinical outcomes.

What Does This Mean for Alzheimer’s Disease?

Research into fungal organisms, mycotoxins, and Alzheimer’s disease is still evolving. Although these findings are scientifically interesting, they do not establish fungal infection or mycotoxin exposure as a proven cause of Alzheimer’s disease, and neither fungal testing nor mycotoxin testing is currently an established standalone diagnostic method for Alzheimer’s disease.

Understanding the potential contributions of infectious agents, environmental exposures, genetics, and other biological processes may eventually help researchers develop a more complete picture of this complex condition.

At Valley Integrative Health, we believe that evaluating cognitive health requires a thoughtful, individualized approach that considers established risk factors, appropriate diagnostic testing, and the current scientific evidence.

Scientific References

1. 2015 study: Fungal infection and Alzheimer’s disease — Scientific Reports
2. 2021 study: Mycotoxins and neurodegenerative diseases — Toxins