Most dementia-prevention advice centers on food, puzzles, or supplements, habits aimed directly at the brain. Two studies looking at other everyday factors suggest some of the most effective levers aren’t brain habits at all, they’re the ears and the body, and the evidence for both is stronger than casual advice usually lets on.
The clearest evidence comes from the 2023 ACHIEVE trial by Frank Lin, James Pike, Marilyn Albert, and colleagues, published in The Lancet. The researchers randomly assigned 977 adults aged 70 to 84 with untreated mild-to-moderate hearing loss to either a hearing intervention, hearing aids plus audiologic counseling, or a health-education control, then tracked their cognitive function for three years. In the subgroup drawn from a cohort of older, higher-risk participants who were already showing more signs of age-related cognitive vulnerability, those who received the hearing intervention showed their cognitive decline slow by 48 percent compared to the control group. This was a randomized trial, not just an observational link, making it the first strong causal evidence that treating a common, often-ignored condition, hearing loss, can directly protect cognitive function over time, exactly the kind of modifiable risk factor major dementia-prevention research has increasingly pointed to.
A second study helps show that physical activity carries a similarly strong, dose-dependent effect. In a 2023 systematic review and meta-analysis by Xiaoqian Zhang and colleagues, published in Ageing Research Reviews, the researchers pooled data from 29 prospective cohort studies covering more than 2 million participants. Overall, physical activity was linked to a 28 percent lower risk of Alzheimer’s disease, a link that held up even after adjusting for the widest range of other health and lifestyle factors the researchers could control for. The relationship wasn’t flat, it scaled clearly with intensity. High-intensity physical activity was linked to a 44 percent lower risk, moderate activity to a 15 percent lower risk, and low-intensity activity showed no significant protective effect at all. Simply moving more wasn’t enough, the protective effect specifically tracked with how vigorously people were moving.
Together, these two studies widen the picture of what actually reduces dementia risk beyond diet and mental puzzles. Lin and colleagues’ research shows that treating hearing loss, something many people quietly put off for years, produced a measurable slowing of cognitive decline in a rigorously controlled trial. Zhang and colleagues’ research shows that physical activity’s protective effect against Alzheimer’s isn’t just real but graded, with real intensity doing meaningfully more than casual movement. Between the two, two of the most overlooked levers for lowering dementia risk turn out to be a hearing test and a genuinely challenging workout, not another supplement or crossword puzzle.
It’s worth being honest about what these two studies don’t establish. The ACHIEVE trial’s strongest effect showed up specifically in a higher-risk subgroup rather than uniformly across the full study population, so the size of the benefit likely depends on a person’s existing risk profile. Zhang and colleagues’ meta-analysis is built from observational cohort studies, and while the dose-response pattern strengthens the case, it can’t fully rule out that healthier people were simply more likely to exercise vigorously in the first place, rather than the exercise itself driving the entire effect.
Within those honest limits, the research offers a genuinely practical starting point for anyone thinking seriously about dementia risk. Getting hearing checked, and treated if needed, and choosing activity that’s genuinely vigorous rather than just present, are two concrete, actionable habits with real trial and cohort evidence behind them, not just plausible-sounding advice.