A Fungal Infection in the Brain Could be Linked to Alzheimer’s, Study Suggests

Although 60 percent or more of dementia cases are caused by Alzheimer’s disease, its cause is still unknown. A small study, however, has found a link between the disease and fungal infections.

Fungus in Brain Samples

For a study published in Scientific Reports, researcher Luis Carrasco, of Spain’s University of Madrid, and his team analyzed cadaver brains from 14 Alzheimer’s patients. In each patients’ brain sample, the molecular biologists found evidence of fungal infection. The fungi were both in the brain cells and outside the cells. Other evidence of fungal infections, such as fungal DNA and proteins, were present in both the brain tissue and the blood serum of the test subjects. The scientists had previously examined four other brains from Alzheimer’s patients, and fungi were present in those samples as well.

The fungal evidence was present in multiple regions of the brain. The team gave in-depth analysis to one sample in particular, referred to as AD1. Throughout the four regions of AD1’s brain that were studied, multiple fungal species were found, but no one species was present in all four regions. As a control, similar samples from the same regions of the brain were taken from a control subject without Alzheimer’s disease, and the researchers found no evidence of fungi in these corresponding samples.

The team also studied the brains of 10 other control cadavers who had never had Alzheimer’s disease. In all of the control samples, the researchers detected no sign of the fungal infections present in the other brains.

Possible Connections

Even though the fungus was found in all of the Alzheimer’s patients’ brains in this study, fungal infections are probably not the cause of all Alzheimer’s disease. For instance, other studies have found a genetic link in a small number of cases.

However, this study implies that there might be a connection between the fungus and Alzheimer’s disease. Perhaps the disease makes brains more vulnerable to infection, and the fungus takes hold after the onset of Alzheimer’s. On the other hand, the fungus could precede the disease. For example, patients whose bodies are dealing with an infection might be more susceptible to cognitive diseases.

Another possibility is that the infection itself is the cause of some Alzheimer’s disease cases. The infection may trigger immune system and inflammation responses, which in turn initiate a process of cognitive impairment. Lending support to this idea is the fact that, just as Alzheimer’s typically comes on slowly, so too does a fungal infection spread slowly. Perhaps as the infection worsens, the disease becomes more pronounced.

Further studies will hopefully better define whether there is an Alzheimer’s-fungus connection and, if so, what it is. A clearer understanding of what role fungus plays in the disease has the potential to shape future options for treating, or even preventing, Alzheimer’s disease.