What can I do to keep my brain healthy as I age?

Of the four levers covered in these records, exercise stands out by far as something you can act on right now. Large, well-designed studies, including controlled experiments, show that regular physical activity improves memory and planning ability and slows cognitive decline. The effect is not spectacular but it is consistent, and even walking or cycling at moderate intensity counts. No prescription, no cost, you can start tomorrow.

Sleep and loneliness appear in the data as factors associated with a higher risk of dementia, but an important nuance applies here: for both, reverse causality plays a real role, meaning that early brain changes may already be disrupting sleep and social functioning before a person receives a diagnosis. That makes these associations less useful as clear causal targets, but it does not make them worthless. Structurally poor sleep or prolonged social isolation is not a neutral state under any circumstances, and if there is room for improvement in those areas that is worthwhile, even without the evidence being one hundred percent conclusive.

Diet is, honestly, the area where expectations need the most adjusting. Observational research looked promising, but the only rigorous controlled study, the MIND trial in older adults over three years, found no significant cognitive benefit. That does not mean healthy eating has no value for the rest of your health, but specifically for cognitive protection the evidence is currently weak.

If you want to prioritise one thing based on what stands on the firmest ground here: move more, regularly and consistently.