Rethinking the plaques and tangles of Alzheimer’s.

Alzheimer’s disease affects over 40 million1) people worldwide and is by far the most common neurodegenerative disorder. As the 6th leading cause2) of death in the U.S., the disease will touch most of our lives in some way. Although Alzheimer’s disease has been intensely studied for some time, its causes are still poorly understood. At best, we know that the brains of Alzheimer’s sufferers are cluttered with protein tangles and plaques3). A popular hypothesis4) is that these plaques cause the disease by slowly degrading the brain tissue around them as they grow. But several drugs that halt the growth of plaques have failed to show any effect on the symptoms5) of the disease in clinical trials6). These perplexing results have left the medical community scratching their heads. Are plaques a consequence rather than the root cause of the disease? And if so, what else is happening in the brains of Alzheimer’s sufferers?

Inflammation is a hallmark of the disease.

Ever since Alzheimer’s was first described at the turn of the 20th century, researchers have noticed telltale signs7)of inflammation in the bodies and brains of Alzheimer’s patients. People with the disease have inflamed blood vessels8) and brain tissue and their brains are awash with immune system molecules. These patterns tell us that the inflamed brains of Alzheimer’s patients are responding as though they’re battling infection. And according to a recent study9), led by Dr. Luis Carrasco of the Autonomous University of Madrid and published last month in Scientific Reports, the brains of Alzheimer’s sufferers are infected with fungi. The researchers studied the brain tissue of deceased Alzheimer’s patients and of people who had shown no signs of Alzheimer’s. The team’s findings were stark: all of the Alzheimer’s brains were riddled with at least one type of fungus, while none of the healthy brains showed any evidence of fungal infection.


brain health

Fungus and Alzheimer’s may go hand in hand.

This new study is one of several linking fungal infection to Alzheimer’s disease. Fungus has also been found in the spinal fluid10) of Alzheimer’s patients. Chitin, a substance that makes up fungal cells but not human cells, is found in the Alzheimer’s brain11). In a surprising turn, beta-amyloid, the plaque-forming peptide long thought to be the major culprit in Alzheimer’s, was recently shown to have antimicrobial properties12). Beta-amyloid is especially effective against the fungus Candida albicans, a common cause of “yeast infections”. These results may force us to rethink Alzheimer’s as a response to an infection instead of a disease caused by protein structures gone awry. In this new way of seeing the disease, the plaques found in the Alzheimer’s brain, long believed to cause the disease, may actually be fighting infection there.

Where do we go from here?

We would be amiss to say “Aha, now we know the cause of Alzheimer’s!” What this study tells us is that fungal infections are especially common in the Alzheimer’s brain. What it doesn’t tell us is whether fungus causes Alzheimer’s. The disease may still be caused by some other damaging source that opens a doorway to the brain and lets fungus and other pathogens, like viruses and bacteria13), gain footing there. As a functional medicine doctor, I help my patients understand that many diseases come about through a culmination of factors. So while it is tempting to search for a single, simple cause of a disease, that search is often misleading. Just as you are a product of your genetics, diet, environment, and culture, so is your health. So I will go out on a limb and say it is unlikely that all Alzheimer’s sufferers have the disease because of “fungal infections in the brain.” However, two14)tantalizing studies show that this finding could be relevant to at least some Alzheimer’s patients: when two patients15) who had previously been diagnosed with Alzheimer’s were treated with antifungal drugs, their cognitive symptoms disappeared. There is still much to be studied. However, we may one day be able to slow or halt the disease in some Alzheimer’s patients by using something as simple as treating them with antifungal drugs, dietary changes, and nutrients.

How to add this discovery to your actionable toolkit.

If you or a loved one have recently been diagnosed with Alzheimer’s, ask your doctor to run some tests to check for evidence of fungal infection. These tests may be as simple as a blood workup, or they may require a check of the cerebrospinal fluid through the use of a spinal tap.