Cognitive reserve
How much wear your brain can take before it shows. Built over years of demanding things, not by an app.
Cognitive reserve is the idea that a brain used hard for a lifetime can take more damage before its owner notices anything wrong. Two people can have the same changes in the brain, and only one of them struggles day to day. The other has more reserve. Evidence: decent It's a framework researchers use to explain that gap.
In 2024 a panel of experts writing in The Lancet, a major medical journal, listed 14 risk factors for dementia that can in principle be changed. Dementia is when memory and thinking fail badly enough to wreck daily life. Dealing with all of them could, they estimated, prevent or delay about 45 per cent of cases. Evidence: decent That's a figure for whole populations. It is not your personal odds, and it doesn't promise any one man anything.
Two things get oversold. Brain-training apps make you better at the app and little else. Evidence: solid That they build reserve hasn't been shown. Evidence: decent And "use it or lose it" gets sold as proven cause and effect. It may run the other way too: a brain already starting to slip can be the reason someone stops reading, working or going out. Evidence: decent
Why it matters
The honest version is modest. Keep doing hard, real things for years, and keep moving. Start with one hard skill and walking. The rest is in Keeping your brain plastic.
If your memory is getting worse, not just busier, and people around you have noticed, see a doctor. Some causes are treatable, which is the point of going early.