Alzheimer's Disease is the most common form of dementia, which the World Health Organization (WHO) says affects nearly 50 million people worldwide. About 7.7 million new cases are diagnosed per year. Old age is the major risk factor for Alzheimer's Disease, and there is no therapy to stop or reverse Alzheimer's symptoms, which include memory loss and disorientation, as well as anxiety and aggressive behavior. Some researchers have suggested that Alzheimer's Disease may be an infectious disease or, at least, that infection with certain microbes may boost Alzheimer's risk.
In a new study, Spanish researchers have discovered traces of fungus in the brains of Alzheimer's sufferers. This discovery has relaunched the question whether Alzheimer's Disease is caused by an infectious microbe? There is no conclusive evidence yet, but if the answer turns out to be 'yes', it means Alzheimer's Disease may be targeted with antifungal treatment.
The researchers wrote, "The possibility that Alzheimer's Disease is a fungal disease, or that fungal infection is a risk factor for the disease, opens new perspectives for effective therapy for these patients."
The five-member research team found cells and other material from several fungal species in the brain tissue and blood vessels of all 11 deceased Alzheimer's patients that they analyzed, while the fungal species were not found in the brain of ten Alzheimer's-free controls.
The study authors said, "Genetic material from viruses and bacteria had previously been found in the brains of Alzheimer's patients, and viruses which cause herpes and pneumonia have been suggested as potential Alzheimer's disease 'agents'."
The main suspect in Alzheimer's disease to date has been 'brain plaques' caused by a build-up of sticky proteins, but clinical trials with drugs targeting these have yielded disappointing results. This new study adds another possible cause to the list of hypotheses.
The researchers said, "Traces of several fungal species were found, which might explain the diversity observed in the evolution and severity of clinical symptoms in each Alzheimer's disease patient. A fungal cause would fit well with the characteristics of AD, the researchers added, including the slow progression of the disease and inflammation, which is an immune response to infectious agents such as fungi. However, the fungal infection may be the result, not the cause, of Alzheimer's disease."
They further added, "Alzheimer's sufferers may have a weaker immune response, or changes in diet or hygiene, that could leave them more exposed. It is evident that clinical trials will be necessary to establish a causal effect of fungal infection of Alzheimer's disease. There are at present a number of highly effective antifungal compounds with little toxicity. A combined effort from the pharmaceutical industry and clinicians is needed to design clinical trials to test the possibility that Alzheimer's disease is caused by fungal infection."
The study is reported in Scientific Reports.