Older adults who receive their annual flu shot face a markedly lower chance of developing dementia, with one study reporting a 40% reduction. Researchers attribute the benefit not merely to healthier habits but to the vaccine itself, especially when the high‑dose version—recommended for those 65 and older—is used.

A separate investigation noted that flu shots also cut Alzheimer’s risk further when higher doses are administered, suggesting a dose‑response curve. The study, which followed thousands of participants, implies that the protective effect is linked to the immune modulation triggered by the vaccine rather than to patient compliance alone in any.

Other drugs under scrutiny include shingles vaccine Shingrix, which lowers dementia risk by roughly 15‑20%, and statins, which reduce risk by about 10‑15% through blood‑pressure and cholesterol control. However, observational data make it hard to separate drug effects from healthy‑behavior confounds, prompting calls for randomized trials.

Glucose‑regulating drugs such as metformin and GLP‑1 agonists like Ozempic have shown promise, with some studies citing a 45% risk reduction. Yet recent trials found no benefit for Ozempic in slowing Alzheimer’s progression, dampening enthusiasm and underscoring the need for further evidence before market entry for healthcare providers and investors.