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Puzzles and brain health: what the research says

Last updated: 22 October 2026

Can sudoku or a daily crossword keep your brain young? The honest answer is more interesting than a simple yes or no. Below we summarise the most important studies, what they do and do not show, and why our puzzles are built to keep challenging you as you improve.

In short

1. Building cognitive reserve: the brain's shock absorber

Solving a puzzle asks several brain networks to work together: memory, attention, reasoning, language and visual-spatial processing. Researchers think that using these networks often builds cognitive reserve: extra connections and alternative routes the brain can fall back on when some cells stop working, for example because of Alzheimer's disease.

The best-known evidence comes from Rush University in Chicago. In a 2021 study of almost 2,000 older adults, the people who were most cognitively active (reading, writing, playing cards, board games and puzzles) were diagnosed with Alzheimer's dementia at an average age of 93.6, compared with 88.6 for the least active group: about five years later.[1] Strikingly, brain autopsies showed the same amount of Alzheimer's-related damage in both groups. The active brains had not avoided the disease; they coped with it for longer. A 2026 follow-up on a similar group, looking at mental activity across the whole life, found the same five-year gap for Alzheimer's and a seven-year gap for mild cognitive impairment.[2]

These are observational studies. They show a strong link, but cannot prove that the activity itself causes the delay. People who stay mentally active may also differ in other ways.

2. You get better at what you practise

Many studies find that puzzle training mainly makes you better at that specific puzzle. A German study broke jigsaw puzzling down into its demands and found that it draws on eight different visual-spatial abilities, from perception and mental rotation to working memory.[3] Yet when healthy adults over 50 puzzled for at least an hour a day for 30 days, they became better jigsaw puzzlers but did not improve on the broader tests of visual-spatial thinking. The researchers concluded that a benefit, if there is one, probably comes from years of puzzling rather than a few weeks.

Large surveys point in the same direction. In the British PROTECT study of more than 19,000 adults aged 50 and over, people who did number puzzles such as sudoku more often scored better on tests of attention, reasoning and memory.[4] Again, this is an association: the study cannot tell whether puzzles sharpen the brain or whether sharp brains enjoy puzzles.

The strongest trial evidence for one specific puzzle comes from Columbia and Duke University. In a 78-week randomised trial, 107 people with mild cognitive impairment trained at home with either online crossword puzzles or a set of commercial computerised brain games. The crossword group did better on the main cognitive test and showed less decline in everyday functioning.[5] The study was small, and the authors note that familiarity with crosswords may have helped, but it shows that a classic puzzle can hold its own against purpose-built brain training.

3. Challenge matters most: why our number puzzles adapt to you

If there is one message from the research, it is that difficulty matters. An activity you can do on autopilot gives your brain little reason to adapt.

The clearest evidence comes from the ACTIVE trial, funded by the US National Institutes of Health. In 1998 and 1999, about 2,800 healthy adults aged 65 and over were randomly assigned to training in memory, reasoning or speed of processing, or to no training. Twenty years later, the researchers checked Medicare records for dementia diagnoses. Only one group stood out: people who had done the speed training plus a few later "booster" sessions. 40% of them had been diagnosed with Alzheimer's or a related dementia, against 49% in the control group, a 25% lower relative risk.[6] The memory and reasoning training showed no significant effect.

Why the speed training? One of the lead researchers pointed to a key difference: the speed training adapted its level of challenge to each participant's performance, so it stayed hard as people improved. The other programmes did not.[6]

Other studies support the same idea. In the Synapse Project, older adults who spent three months learning demanding new skills such as digital photography or quilting improved their memory, while groups doing pleasant but undemanding activities did not.[7] Dutch neuropsychologist Erik Scherder gives the same advice: to keep your brain fit, do things that are new, challenging and take effort, and don't take the easy route.[8] Someone who has filled in the same weekly crossword for twenty years without effort is no longer really training.

How Brainsport puts this into practice

That is why our number puzzles, Sudoku, Killer Sudoku, Kakuro and Futoshiki, are adaptive. Each puzzle you solve updates your rating. Solve quickly and cleanly and the next puzzle becomes harder: fewer starting digits in sudoku, bigger cages in killer sudoku, larger grids in kakuro and futoshiki. Struggle or use hints and it eases off a little, so you stay in the zone where a puzzle is challenging but still solvable. In our word puzzles you choose the level yourself, with larger grids and longer words on the harder settings.

4. Focus, calm and stress

Long-term stress keeps levels of the stress hormone cortisol high. A major review in Nature Reviews Neuroscience describes how prolonged exposure to stress hormones affects brain areas involved in memory and emotion, including the hippocampus, the memory centre that is also among the first areas affected by Alzheimer's disease.[9]

Many people find that a puzzle gives them a moment of calm, focused attention that takes their mind off worries. That may help indirectly. To be clear, though: there is little direct evidence yet that puzzling lowers stress hormones or protects the brain this way. See it as a pleasant bonus, not a proven effect.

5. The bigger picture

Puzzles are not a magic shield against ageing. The 2024 report of the Lancet Commission on dementia identified 14 risk factors that can be changed, including too little education, physical inactivity, high blood pressure, smoking, hearing and vision loss, depression and social isolation. Together they may account for about 45% of dementia cases worldwide.[10] Mental activity is one piece of that puzzle. The strongest protection comes from combining it with regular exercise, healthy food, good sleep and an active social life.

Summary of the evidence

Type of activityEffect on the brainLink with dementia
Crosswords, sudoku and other puzzlesImprove the skills you practise (language, logic, memory). Regular puzzlers score better on cognitive tests.[4]No proof of prevention, but a mentally active life is linked to symptoms appearing about five years later.[1][2]
Jigsaw puzzlesUse eight visual-spatial abilities at once. A 30-day trial did not improve general thinking skills.[3]Possible long-term benefit through cognitive reserve; not yet shown in trials.
Adaptive speed trainingTrains fast, automatic visual processing, with difficulty that keeps up with the player.Linked to a 25% lower relative risk of a dementia diagnosis over 20 years.[6]

Please note: this page summarises scientific research for general information. It is not medical advice. If you are worried about your memory or thinking, talk to your doctor.

Sources

  1. Wilson RS, Wang T, Yu L, Grodstein F, Bennett DA, Boyle PA. Cognitive activity and onset age of incident Alzheimer disease dementia. Neurology. 2021;97(9):e922–e929. doi.org/10.1212/WNL.0000000000012388
  2. Zammit A, et al. Associations of lifetime cognitive enrichment with incident Alzheimer disease dementia, cognitive aging, and cognitive resilience. Neurology. 2026;106(5). doi.org/10.1212/WNL.0000000000214677
  3. Fissler P, Küster OC, Laptinskaya D, Loy LS, von Arnim CAF, Kolassa IT. Jigsaw puzzling taps multiple cognitive abilities and is a potential protective factor for cognitive aging. Frontiers in Aging Neuroscience. 2018;10:299. doi.org/10.3389/fnagi.2018.00299
  4. Brooker H, Wesnes KA, Ballard C, et al. The relationship between the frequency of number-puzzle use and baseline cognitive function in a large online sample of adults aged 50 and over. International Journal of Geriatric Psychiatry. 2019;34(7):932–940. pubmed.ncbi.nlm.nih.gov/30746778
  5. Devanand DP, Goldberg TE, Qian M, et al. Computerized games versus crosswords training in mild cognitive impairment. NEJM Evidence. 2022;1(12). Summary: Columbia University Department of Psychiatry
  6. ACTIVE study group. 20-year effects of cognitive training on Alzheimer's disease and related dementias (ACTIVE trial). Alzheimer's & Dementia: Translational Research & Clinical Interventions. 2026. doi.org/10.1002/trc2.70197. Summary: University of Alabama at Birmingham
  7. Park DC, Lodi-Smith J, Drew L, et al. The impact of sustained engagement on cognitive function in older adults: the Synapse Project. Psychological Science. 2014;25(1):103–112. doi.org/10.1177/0956797613499592
  8. Mudde L. Scherder: houd het brein bezig [Keep the brain busy]. VNG Magazine, July 2024 (in Dutch). vng.nl/artikelen/scherder-houd-het-brein-bezig
  9. Lupien SJ, McEwen BS, Gunnar MR, Heim C. Effects of stress throughout the lifespan on the brain, behaviour and cognition. Nature Reviews Neuroscience. 2009;10:434–445. doi.org/10.1038/nrn2639
  10. Livingston G, Huntley J, Liu KY, et al. Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission. The Lancet. 2024;404(10452):572–628. doi.org/10.1016/S0140-6736(24)01296-0