This confirms that gut bacteria are involved in causing Alzheimers. Specific bacteria in the gut are directly linked to cognitive decline in Alzheimer's patients.

Gut microbiota actually play a causal role in the development of symptoms of the devastating disease.

Human participants, including 69 with Alzheimer's disease and 64 healthy controls, donated blood for research, with some from each group also providing gut microbiota via stool samples.

Gut microbiota from Alzheimer's patients was transplanted into 16 young adult rats whose microbiomes had been depleted by antibiotics for a week. A matching group of 16 rats received gut microbiota from humans in the healthy control group.

At least 10 days after the transplants, the rats were subjected to behavioral tests designed to evaluate memory performance as well as other traits associated with Alzheimer's disease.

Rats that had microbiome transplants from Alzheimer's patients showed impaired memory behaviors, particularly those that rely on a process called adult hippocampal neurogenesis.

Hippocampal neurogenesis creates new neurons in the hippocampus, a region of our brains that's important for memory and mood, and one of the first areas impacted by Alzheimer's.