Do brain games and crosswords actually lower dementia risk?

Here's the honest answer the app-store ads won't give you: most commercial "brain games" mainly make you better at the game you're playing — not at real-world thinking, and not at lowering dementia risk. That gap is exactly why the US Federal Trade Commission fined the maker of Lumosity $2 million in 2016 for deceptive advertising. Crosswords, sudoku and puzzles are enjoyable, low-risk and associated with benefit in observational studies — but association isn't proof, and no puzzle has been shown to prevent dementia. There's one important exception with real long-term evidence, which we'll get to. The short version: do the games you enjoy, but don't expect any of them to be a shield.

The core problem: "narrow transfer"

When scientists test brain-training games properly, they keep running into the same wall, and it has a name: narrow transfer. Practise a task and you get better at that task — sometimes dramatically. Spend weeks matching symbols against the clock and your symbol-matching score climbs. The trouble is that the improvement usually stays trapped inside the game. It rarely "transfers" to the things you actually care about: remembering names, following a fast conversation, managing your money, driving safely. You've trained a very specific skill, not your brain in general. That's the honest scientific consensus on most commercial brain-training: people get better at the trained games, with limited evidence that it carries over to everyday cognition or changes long-term risk. A game feeling harder — or your score going up — is not the same as your real-world thinking getting sharper.

Does Lumosity work? What the FTC found

This is where the most famous cautionary tale comes in. Lumosity built a huge business on the promise that a few minutes of its games could sharpen your mind and hold off decline. In January 2016, the Federal Trade Commission announced that Lumosity's maker, Lumos Labs, had agreed to pay $2 million to settle charges of deceptive advertising. The regulator's language was blunt: the company had, in its words, preyed on consumers' fears about age-related cognitive decline while lacking the science to back its claims — including claims that training with Lumosity could delay age-related decline and protect against mild cognitive impairment, dementia and Alzheimer's. (The order also carried a much larger judgment that was suspended because of the company's finances.)

The lesson isn't that Lumosity is uniquely bad — it's that the entire category tends to market far ahead of its evidence. "Clinically designed," "backed by neuroscience" and glossy brain imagery can sit on top of very little proof that the product changes your life outside the app. Read brain-game marketing the way you'd read any advertisement, and be especially wary of anything promising to lower your dementia risk.

Are crosswords and sudoku good for your brain?

Here's the fairer, more encouraging side — because "brain games don't work" is too blunt. Crosswords, sudoku, jigsaw puzzles, word games and the like are genuinely worthwhile in the ways that count day to day: they're enjoyable, low-risk, mentally engaging, and they give you a reason to keep your mind active. And observational studies do lean in a hopeful direction — people who regularly do mentally stimulating activities tend to have a lower risk of cognitive decline and dementia than people who don't.

But it's important to be honest about what that evidence can and can't say. Observational studies show a link, not cause and effect. People who do lots of puzzles often differ in other ways — more education, more social contact, better overall health, more active lifestyles — and some early changes in the brain can quietly reduce the appetite for challenging mental activity years before a diagnosis, which can make the puzzles look more protective than they are. No crossword has been shown in a randomised trial to prevent dementia. So the sensible reading is: if you love the daily crossword, keep doing it — it's a healthy, pleasant habit and it may help. Just treat it as one strand of a fuller life, not a guarantee, and not a reason to skip the factors with stronger evidence behind them.

The exception with real evidence: speed-of-processing training

If you take one nuance from this article, make it this one. Not all "brain training" is equal, and there is a single standout with long-term evidence behind it: speed-of-processing training. Processing speed is how quickly you take in information and act on it, and it was tested in the ACTIVE trial, which randomised older adults into cognitive-training groups and followed them for around a decade. Two things set it apart from the app-store crowd: the gains lasted for years rather than fading, and over the long follow-up, speed-of-processing training was linked to a lower risk of dementia compared with the control group.

Read that precisely: linked to, not proven to prevent. It's one important line of evidence from one trial, and researchers still debate exactly how far the benefits carry. But it's the reason speed training stands apart from the typical game — and it's worth understanding properly. We go deep on it in processing-speed training: the one brain exercise with 20-year evidence. The takeaway for this piece is simply that "brain games are useless" is as wrong as "brain games are magic." The specifics matter, and the evidence points at a particular kind of drill rather than at puzzles or the flashiest app.

What actually matters: novelty, new skills, and staying engaged

Step back and a clearer principle emerges from the research. What seems to help your brain isn't any single app or puzzle — it's novelty, genuine learning, and staying mentally and socially engaged over time. Doing the same familiar game on autopilot asks little of you once you've mastered it. Learning something genuinely new — a language, an instrument, a craft, a dance, a route you've never walked — keeps demanding fresh effort, and it usually pulls in other protective factors too: it gets you moving, connects you with people, and gives structure to your week. Social connection and physical activity are themselves among the modifiable factors associated with lower dementia risk, so a hobby that combines mental challenge with company and movement is doing several useful jobs at once.

That reframes the whole "brain games" question. The point isn't to grind a leaderboard; it's to keep your mind curious and stretched, alongside the health and lifestyle levers that carry the strongest evidence — blood pressure, hearing, sleep, exercise, mood and staying connected. Those are the moves the research keeps returning to, and unlike most of the app store, they're backed by large, long, independent studies. So enjoy your crossword. Play the game you like. Just don't let a game stand in for the things that actually count — tracked, unglamorous and repeated, because consistency is what moves the needle.

How we research and review our content →

This article is educational and is not medical advice, diagnosis, or treatment. Studies and products mentioned describe the evidence and risk factors in general, not Solenna specifically. Solenna does not diagnose, prevent, treat, or cure Alzheimer's disease or any form of dementia; individual results vary and no outcome is guaranteed. If you are concerned about your cognitive health, consult a qualified healthcare professional.