Why the brain’s microbiome could hold the key to curing Alzheimer’s

It looked like a classic case of Alzheimer’s disease. For three years, a man in his 70s suffered severe cognitive decline: He often forgot the names of family members and was no longer able to drive or leave the house by himself. Further deterioration seemed inevitable. But then the doctors checked. A sample of his cerebrospinal fluid And saw a fungus called Cryptococcus neoformans. When they put him on a course of antifungal medication, the results were shocking. Within two years, he had regained his driver’s license and was back at work as a gardener.

Neuroscientists have long suspected that certain infections may increase the risk of dementia. For example, both Porphyromonas gingivalisthe bacteria behind gum disease, and Herpes simplex viruswhich causes cold sores, Has been linked to Alzheimer’s. But cases of “reversible dementia” are beginning to generate a lot of interest in the idea that our brains are full of microorganisms — and that an imbalance in this “brain microbiome” can predispose people to the neurodegenerative disease.

Until recently, the brain was thought to be devoid of microbes, at least because of the blood-brain barrier, a special membrane that keeps pathogens and toxins in the blood out of the brain. So the idea of ​​a brain microbiome was controversial. However, a new study seems to put the matter to rest. Richard Leith At the University of Edinburgh, UK, and colleagues analyzed data from postmortem brains. Stored in four brain banks in the UK and USA. They found a wide variety of different types of microbes and…