Evidence for Mental Fitness #

Every substantive claim on the Mental Fitness page is checked against current research. Here is each claim, how well today’s evidence supports it, and the sources. The full, de-duplicated source list lives on the references page.

Supported · strong evidence — Commercial ‘brain-training’ games and software do not reliably make you generally smarter; the evidence for broad cognitive benefit beyond the trained tasks is weak.

The page debunks the brain-training-makes-you-smarter claim. Simons et al.’s comprehensive review of the brain-training literature found extensive evidence of improvement on the trained tasks but little compelling evidence that training improves everyday cognitive performance; this remains the consensus in 2026.

Sources: Simons, D. J., et al. (2016), Do ‘Brain-Training’ Programs Work? Psychological Science in the Public Interest — https://doi.org/10.1177/1529100616661983 · full reference ›

Supported · strong evidence — Practising a cognitive task reliably improves performance on that task and very similar ones (near transfer), and this is the bulk of what brain-training games deliver.

Robust task-specific (near) gains from practice are uncontested; Simons et al. (2016) document that brain-training studies consistently show improvement on the trained task even where broader transfer is absent.

Sources: Simons, D. J., et al. (2016), Do ‘Brain-Training’ Programs Work? — https://doi.org/10.1177/1529100616661983 · full reference ›

Supported · strong evidence — Far transfer — a narrow trained exercise lifting general cognitive ability — largely does not occur, across brain-training games, chess, and music practice.

Sala & Gobet’s syntheses across working-memory training, chess and music find reliable near transfer but little to no far transfer to general cognition; the strong-near/weak-far asymmetry is well established in the 2026 literature.

Sources: Sala, G., & Gobet, F. (2017), Does far transfer exist? Negative evidence from chess, music, and working memory training. Current Directions in Psychological Science — https://doi.org/10.1177/0963721417712760 · full reference ›

Supported · strong evidence — Aerobic exercise improves cognition — including attention, processing speed and memory — and is one of the most effective levers for keeping the mind sharp.

Hillman, Erickson & Kramer review converging human and animal evidence that aerobic fitness benefits brain structure and cognitive function across the lifespan; the link between aerobic exercise and cognition is well supported in 2026, though effect sizes vary by population and outcome.

Sources: Hillman, C. H., Erickson, K. I., & Kramer, A. F. (2008), Be smart, exercise your heart: exercise effects on brain and cognition. Nature Reviews Neuroscience — https://doi.org/10.1038/nrn2298 · full reference ›

Supported · moderate evidence — In older adults, regular physical exercise produces measurable improvements in cognitive function.

Northey et al.’s systematic review and meta-analysis of adults over 50 found exercise interventions improved cognitive function, with benefits across aerobic and resistance training. Effects are modest and design quality varies, but the direction is well supported.

Sources: Northey, J. M., et al. (2018), Exercise interventions for cognitive function in adults older than 50: a systematic review with meta-analysis. British Journal of Sports Medicine — https://doi.org/10.1136/bjsports-2016-096587 · full reference ›

Supported · moderate evidence — A sustained programme of aerobic exercise can increase hippocampal volume and improve memory in older adults.

Erickson et al.’s randomized controlled trial found a year of aerobic walking increased anterior hippocampal volume by ~2% and improved spatial memory in older adults. It is a single well-cited trial in an older sample, so the specific volumetric effect is best described as moderate rather than definitively generalisable.

Sources: Erickson, K. I., et al. (2011), Exercise training increases size of hippocampus and improves memory. PNAS — https://doi.org/10.1073/pnas.1015950108 · full reference ›

Supported · strong evidence — Sleep supports cognition: it consolidates newly learned material and restores attention, so protecting sleep does more for learning than brain-training games.

Walker reviews extensive evidence that sleep both consolidates memories and is necessary for attention and learning, with sleep deprivation impairing these functions; the role of sleep in cognition and memory consolidation is well established in 2026.

Sources: Walker, M. P. (2009), The role of sleep in cognition and emotion. Annals of the New York Academy of Sciences — https://doi.org/10.1111/j.1749-6632.2009.04416.x · full reference ›

Supported · strong evidence — The most effective way to improve at a specific skill is to practise that skill itself, because the gains are task-specific rather than broadly transferable.

Follows directly from the near/far transfer evidence: because practice produces reliable task-specific gains but little far transfer (Sala & Gobet 2017; Simons et al. 2016), deliberately practising the target skill is the dependable route to improving it.

Sources: Sala, G., & Gobet, F. (2017), Does far transfer exist? — https://doi.org/10.1177/0963721417712760 · Simons, D. J., et al. (2016), Do ‘Brain-Training’ Programs Work? — https://doi.org/10.1177/1529100616661983 · full reference ›