Mahjong and Dementia: Reading the Studies Carefully
Four large long-term studies, five small trials — and the five questions that decide what each one can actually tell you.
What does “dementia” mean in this study?
Headlines use one word. The studies use three different things. Some count a diagnosis made by a psychiatrist. Some count a screening score that drops below a line — usually fewer than 24 points on the MMSE, a 30-point test of memory, attention and language. Trials usually measure something narrower still: how a score changes over a few months. These are not interchangeable, and the article tells you which one each study used.
Three things called “dementia” in the research
Did the game come first, or the decline?
Dementia develops over many years. Someone in its early, undiagnosed stage may quietly stop playing because the game has become hard. A study that then compares “players” and “non-players” would see fewer diagnoses among players — even if mahjong did nothing at all. Researchers call this reverse causation, and the strongest studies try to design it out.
15,582 adults aged 65+, followed for a median of five years
People aged 65 and over assessed at the Hong Kong government’s Elderly Health Centres between January and June 2005 were asked about “intellectual activities” in the past month — reading, board games, mahjong or card games, and betting on horse racing. Dementia was diagnosed by geriatric psychiatrists. Crucially, the team threw out anyone diagnosed within the first three years, so that people already on the way to dementia at baseline would not distort the result.
How the Hong Kong study handled “the decline came first”
Four cohorts, one direction
Three more studies used the Chinese Longitudinal Healthy Longevity Survey, which has followed older adults across China since 1998. Each measured mahjong a little differently, and each found the same direction.
Risk among frequent players compared with non-players
Two details are worth keeping. In Mao 2020 (adults 80 and over), the link was stronger among those with two or more years of schooling — a hint that the game may work differently depending on who is playing. And a separate snapshot of 7,308 survey participants in 2018 found that regular and occasional players had higher MMSE scores than people who never played — except among those aged 60 to 69, where there was no difference.
What the trials found — and how small they are
Only trials can test cause and effect. For mahjong there are five, all small: four from one Hong Kong team working in nursing homes, and one digital-mahjong program on an iPad in Taiwan (covered in our first article).
Every randomized trial of mahjong, by size
62 people with mild-to-moderate dementia, average age about 84
Mahjong twice or four times a week for 16 weeks. Both groups gained on digit-span, verbal memory and MMSE, and the gains were still there one month later. There was no group that did not play, so the study shows that playing more or less often made little difference — not that mahjong beat doing nothing.
110 nursing-home residents with dementia: mahjong vs. tai chi vs. handicrafts
Reported in two papers. On the MMSE, the mahjong group was 4.5 points higher than the handicrafts group at 9 months (95% CI 2.0–6.9), as we showed in our first article. On the Clinical Dementia Rating — a wider measure of how dementia affects daily life — neither mahjong nor tai chi changed the cognitive or functional components, but the mahjong group’s total score deteriorated more slowly than the comparison group’s. The authors call it “a slightly slower rate of dementia progression”.
36 residents with mild dementia and at least moderate depressive symptoms
The same three activities, three times a week for 12 weeks. The mahjong group’s depression score fell during the program and then climbed back once the sessions ended.
Depression scores in the mahjong group
56 people with mild cognitive impairment, average age 74
In a nursing home in Sichuan, 28 people played mahjong three times a week for 12 weeks and 28 continued their usual day. Scores on a cognitive test (MoCA), a trail-making task and a daily-activities questionnaire improved in the mahjong group and not in the comparison group.
The studies side by side
| Study | Type | Who | “Dementia” measured as | Result | Keep in mind |
|---|---|---|---|---|---|
| Lee 2018 | Cohort | 15,582 adults 65+, Hong Kong, 5 years | Psychiatrist diagnosis | Intellectual activities: OR 0.71 (0.60–0.84) | Mahjong grouped with reading and cards; first 3 years excluded |
| Tian 2022 | Cohort | 11,821 adults 65+, China, 10 years | Dementia diagnosis | Near-daily cards/mahjong: HR 0.63 (0.42–0.95) | Cards and mahjong combined; self-reported |
| Mao 2020 | Cohort | 10,741 adults 80+, China, 3.4 years | MMSE below cut-off | Near-daily cards/mahjong: HR 0.70 (0.56–0.86) | Stronger with ≥2 years of education |
| Qiu 2019 | Cohort | 4,830 adults 80+, China, median 16 years | MMSE below 24 | Frequent social activities incl. cards/mahjong: HR 0.71 (0.60–0.83) | Mahjong inside a wider “interpersonal” category |
| Wang 2022 | Snapshot | 7,308 adults, China, 2018 | MMSE score | Regular and occasional players scored higher | One point in time; no difference at ages 60–69 |
| Cheng 2006 | Trial | 62 people with dementia, Hong Kong | Test scores | Gains after 16 weeks, lasting 1 month | No non-mahjong group |
| Cheng 2012 | Trial | 36 residents with mild dementia | Depression scale | −3.25 points, then +2.83 after stopping | Very small; open-label |
| Cheng 2014 | Trial | 110 nursing-home residents | MMSE; Clinical Dementia Rating | +4.5 MMSE vs. handicrafts; slower CDR deterioration | Open-label; CDR components unchanged |
| Zhang 2020 | Trial | 56 people with MCI, Sichuan | MoCA, trail-making, daily activities | Improved vs. usual activity | Comparison group did nothing extra |
| Tung 2026 | Trial | 60 community-dwelling adults 55+, Taiwan | Delayed recall; brain imaging | Slightly better delayed recall vs. no program | iPad app plus walking rewards, not a physical table; comparison group did nothing |
What we don’t know yet
In most cohorts mahjong sits in a basket with cards, reading or clubs. Nobody has yet isolated the game in a large long-term study.
Only one cohort built in a waiting period to rule out people already declining. The association survived — but it is still an association.
Every study here is from Hong Kong, mainland China or Taiwan, where mahjong is a lifelong habit. We found no studies on Japanese Riichi or Western players.
In the depression trial, gains reversed within six months of stopping. Whether that applies to thinking skills is untested.
Education changed the strength of the link in one study; age changed it in another. The trials were too small to tell.
Five questions to ask of any headline
None of this is medical advice. But the next time you read that a game “cuts dementia risk”, these checks will tell you how much weight the claim can carry.
- What counted as dementia?
A clinical diagnosis, a score below a cut-off, or a change in a test — they are not the same thing.
- Who was the comparison?
People who never played? People who did handicrafts? People who did nothing extra? Each answers a different question.
- Could the decline have come first?
Look for a study that excluded early cases or waited several years before counting.
- Was mahjong measured on its own?
Or was it bundled with cards, chess, reading or “social activities”?
- How many people, for how long?
Trials of 36 to 110 people over 12 weeks can show a signal. They cannot show that a game prevents a disease.
If you or someone close to you is worried about memory or thinking, talk to a healthcare professional. A game night is a good thing in its own right; it is not a substitute for assessment.
References
- Lee ATC, Richards M, Chan WC, Chiu HFK, Lee RSY, Lam LCW. Association of daily intellectual activities with lower risk of incident dementia among older Chinese adults. JAMA Psychiatry. 2018;75(7):697–703. doi:10.1001/jamapsychiatry.2018.0657
- Tian G, Shuai J, Li R, et al. Association between playing cards/mahjong and risk of incident dementia among the Chinese older adults: a prospective cohort study. Front Aging Neurosci. 2022;14:966647. doi:10.3389/fnagi.2022.966647
- Mao C, Li ZH, Lv YB, et al. Specific leisure activities and cognitive functions among the oldest-old: the Chinese Longitudinal Healthy Longevity Survey. J Gerontol A Biol Sci Med Sci. 2020;75(4):739–746. doi:10.1093/gerona/glz086
- Qiu J, Sun H, Zhong C, et al. Reclassified cognitive leisure activity and risk of cognitive impairment in Chinese older adults aged ≥80 years: a 16-year prospective cohort study. Geriatr Gerontol Int. 2019;19(10):1041–1047. doi:10.1111/ggi.13774
- Wang J, Liu N, Zhao X. Association of playing cards or mahjong with cognitive function in Chinese older adults. Int J Environ Res Public Health. 2022;19(15):9249. doi:10.3390/ijerph19159249
- Cheng ST, Chan AC, Yu EC. An exploratory study of the effect of mahjong on the cognitive functioning of persons with dementia. Int J Geriatr Psychiatry. 2006;21(7):611–617. doi:10.1002/gps.1531
- Cheng ST, Chow PK, Yu EC, Chan AC. Leisure activities alleviate depressive symptoms in nursing home residents with very mild or mild dementia. Am J Geriatr Psychiatry. 2012;20(10):904–908. doi:10.1097/JGP.0b013e3182423988
- Cheng ST, Chow PK, Song YQ, et al. Mental and physical activities delay cognitive decline in older persons with dementia. Am J Geriatr Psychiatry. 2014;22(1):63–74. doi:10.1016/j.jagp.2013.01.060
- Cheng ST, Chow PK, Song YQ, Yu EC, Lam JH. Can leisure activities slow dementia progression in nursing home residents? A cluster-randomized controlled trial. Int Psychogeriatr. 2014;26(4):637–643. doi:10.1017/S1041610213002524
- Zhang H, Peng Y, Li C, et al. Playing mahjong for 12 weeks improved executive function in elderly people with mild cognitive impairment: a study of implications for TBI-induced cognitive deficits. Front Neurol. 2020;11:178. doi:10.3389/fneur.2020.00178
- Tung HH, Kuo CY, Lee PL, et al. Digital mahjong-based cognitive engagement intervention for older adults: randomized controlled trial. JMIR Aging. 2026;9:e85339. doi:10.2196/85339
- Tse ZCK, Cao Y, Chau BKH, et al. Does playing mahjong benefit older individuals? A scoping review. J Prev Alzheimers Dis. 2024;11(5):1363–1377. doi:10.14283/jpad.2024.102
This article is for general information only and is not medical advice. It does not diagnose, treat or prevent any condition. If you have concerns about memory or thinking, please consult a qualified healthcare professional. It was researched and written with AI assistance by the ALBAN editorial team; every number was checked against the original papers listed above.