Intestinal microbes are thought to be involved in the development of Alzheimer's disease through the gut-brain-microbiota axis. Gut dysbiosis leads to the release of pro-inflammatory mediators.

Long-term exposure to air pollution was linked to dementia, especially in people with heart failure, ischemic heart disease, and stroke, which all enhanced the link between pollution and dementia.

A high-salt diet led to severe bacterial infections in mice and immune deficiencies in humans, at about 6 grams of salt (equivalent to 2 fast-food meals), through increased glucocorticoids.

A large study has found that taking a daily, low-dose aspirin does not significantly reduce the risk of dementia, Alzheimer's disease, or cognitive decline, compared to a placebo.