Psychology says people who stay mentally sharp into their 80s aren't just lucky with their genes — they're typically the ones who kept challenging their brain every day, maintained strong social ties, and never stopped learning something new

My grandmother is in her eighties and she still corrects me at dinner.

Not gently, either. Last time I was halfway through a story I’ve told before, she cut in with the version I’d used about six years ago, including the detail I’d quietly upgraded to make myself sound better. Then she went back to her crossword. In pen.

People meet her and say she’s lucky. Good genes, they say, like she won something. I’ve watched her fairly closely for a long time now, and I think that explanation is carrying more weight than it should.

Lucky genes are the lazy answer

There’s a group of people researchers call SuperAgers: adults over 80 whose memory scores match people 25 to 30 years younger. A team at Northwestern has been following close to 300 of them since 2000, with annual testing and, in many cases, brain donation afterwards.

Their habits, though, were all over the place. Some ate badly, some smoked, some drank, plenty skipped exercise entirely, and they weren’t medically healthier than their peers. If you were hoping for a smoothie recipe, bad news.

What they did share was people. SuperAgers reported warmer, more trusting relationships than others their age. One researcher described their calendars as jammed with volunteering, classes and social commitments, to the point that booking them for a study visit was a nuisance.

Worth being honest about the limits here: this is a pattern found in people who were already sharp, not proof that a fuller diary will make you one of them. But it’s a consistent pattern, and it shows up again in the next study too.

The thing you’re doing has to be genuinely hard

This is the bit most people get wrong, and I include the version of me who used to think a daily Wordle counted as brain training.

A psychologist named Denise Park ran a study called the Synapse Project, where older adults were randomly assigned to spend around 15 hours a week for three months either learning something properly difficult (digital photography, quilting on programmable sewing machines, or both) or doing something pleasant but easy, like socialising in a group or doing low-effort puzzles.

Only the difficult group improved. Their episodic memory, the kind that stores what actually happened to you, got measurably better, with some effects still showing up a year later. The low-effort groups gained nothing cognitively.

Researchers separate this into “productive” and “receptive” engagement. Productive means you’re building something new and slightly out of reach, so your working memory has to work hard to keep up. Receptive means you’re running on stuff you already know. Crosswords, for someone who has done crosswords daily for forty years, are receptive. Comfortable, sociable, good for you in other ways, but not the thing.

My grandmother took up a musical instrument in her seventies. She is, by her own cheerful admission, mediocre at it. That mediocrity is the entire point.

Isolation is a risk factor, not a mood

The Lancet’s standing commission on dementia updated its numbers in 2024 and concluded that around 45% of dementia cases worldwide are potentially preventable by addressing 14 modifiable risk factors across a lifetime.

Social isolation is on that list. So is untreated hearing loss, which I’d argue is the same problem wearing a disguise, because people who can’t follow a conversation stop going to the conversations. If you’ve been putting off the hearing test, treat it as a brain issue rather than a vanity one.

Talking to people is cognitively expensive in the best way. You’re tracking tone, remembering what they told you last month, choosing your words, reading a face. There’s no app that replicates that load.

Cognitive reserve, without the jargon

The term researchers use for all this is cognitive reserve. In plain English, it’s your brain’s ability to keep functioning even when it’s taking damage, a bit like a backup generator: you don’t notice it’s there until the main power fails, and then it quietly keeps the lights on.

Education, mentally demanding work, and staying socially and intellectually active all seem to build it, and people with more of it decline more slowly. Autopsy studies have found people whose brains were full of Alzheimer’s pathology but who never showed symptoms while alive. The damage was there. The reserve absorbed it.

You don’t finish building reserve at 25. You keep topping it up, or you don’t.

What this looks like on an ordinary Wednesday

Pick one thing you’re currently bad at and stay bad at it in public. A language, an instrument, a dance class, chess, coding, pottery. The discomfort of being the worst person in the room is the active ingredient. Comfort is the placebo.

Put socialising on a recurring calendar slot, like a standing Thursday coffee, so it happens whether or not you feel like it that day.

Get the hearing test.

Stop treating easy games as insurance. Enjoy them, just don’t file them under prevention.

And be suspicious of anyone who tells you it’s all genetic. That story is comforting for exactly one reason: it means there’s nothing to do.

My grandmother has a rule she’s never stated out loud, but I’ve watched her follow it for thirty years. She refuses to be finished with anything: not learning, not arguing, not people, not her ridiculous crossword pen.

I can’t prove how much of her sharpness is luck. Thirty years of watching her argue, learn and refuse to let anything go has told me where I’d put my money.