Brain Disease and the Microbiome

In recent decades the incidence of three devastating brain diseases, Alzheimer's(AD), Parkinson's(PD) and autism, has exploded. Increase in AD and PD is partially explained by increasing population longevity, but the cause of much of their increase has not been determined. Autism is now better recognized, explaining a modest part of the increased incidence, but change in frequency of this disease is much higher than can be explained by more awareness from physicians and the general public.

A logical possible cause of these increases include increased environmental toxins. Indeed, a small number of PD is caused by exposure to certain agricultural chemicals and some AD from aluminum in drinking water. An initial report connecting early childhood vaccinations to autism has been completely discredited by large scale studies.

Typical diet has changed greatly since WW II. Some relationship of diet to AD is quite clear, perhaps attributable to vascular disease promoting AD brain pathology. As research in the microbiome progresses, its effects on the brain have become clearer. Experiments with mice have demonstrated major effects on mouse AD, PD and autism-like behavior by manipulating the mice microbiome. Many researchers are trying to determine which bacterial strains are responsible and how they work to change behavior, brain chemistry and pathology. Since diet controls the microbiome it's likely that western society's recent change to a very unhealthy diet is driving the increase in AD, PD, autism and, perhaps, depression and schizophrenia. All scientists now agree that diet has caused our epidemics of heart disease, stroke and cancer. There's a good chance that other major brain diseases will be added to the list of diet-induced health issues.