Mahjong and your brain: what the research really says

Last time, I shared how my late twenties were spent measuring minds at Brain.com. This time I want to do something a little different and walk you through the studies themselves. If I'm going to tell you mahjong is good for your brain, I want you to see the evidence behind it, including where it falls short.

A quick guide to reading the research

• Randomized trial. Researchers assign people to groups by chance, so the groups start out alike. It is the strongest way to test whether an activity causes a change.
• Cohort study. Researchers follow a large group of people over years and look for patterns. These studies can show a link, but they cannot prove cause and effect.
• MMSE. The Mini-Mental State Exam, a 30-point questionnaire doctors use to screen memory and thinking. It's a test I know well. After Brain.com became Cognitive Care, the MMSE was part of the package we offered to doctors' offices.

Study 1: Hong Kong nursing homes, 2014

Researchers randomly assigned whole nursing homes to one of three activities: mahjong, tai chi, or simple handicrafts. The residents had mild dementia, and the study ran for nine months.

The handicraft group slowly declined. The mahjong and tai chi groups held steady. By nine months, the mahjong players scored 4.5 points higher than the handicraft group on the MMSE, and they also held steady on recalling a list of words after a delay and on repeating back a string of numbers.

The limits: the residents already had dementia, and everyone knew which activity they were doing. Even so, this is the strongest mahjong study we have.

Study 2: An earlier mahjong trial, 2006

The same research team had looked at mahjong eight years earlier. Sixty-two older adults with mild to moderate dementia played either twice or four times a week for sixteen weeks.

Scores improved on every measure, including the MMSE and tests of number and word memory. Two details stood out to me. Playing twice a week worked about as well as playing four times. And the gains were still there a month after the games stopped.

The limit: everyone in the study played, so there was no comparison group to show how much of the improvement came from mahjong itself.

Study 3: Ten years of data from China, 2022

This one is different. Instead of running an experiment, researchers used a national survey that followed older adults across China for up to ten years and compared people who regularly played cards or mahjong with those who didn't. The players had a lower risk of developing dementia over that time.

The limit: this shows a link, not proof. People who stay sharp may simply be more likely to keep playing. That's why I pair it with the trials above, which point the same way.

Study 4: Mahjong and mood, 2019

A University of Georgia team studied nearly 11,000 adults 45 and older in China and found that regular mahjong was linked to fewer symptoms of depression among people living in cities.

The most interesting part was what happened in rural areas, where the researchers noted the game often turns competitive and sometimes becomes gambling. There, the benefit disappeared. I'll come back to that in part 4, because it shaped how I run Open Play.

What it adds up to

A mind kept busy, in good company, on a regular schedule.

Put together, these studies are promising and consistent. In trials, mahjong helped older adults with dementia hold on to memory and thinking skills. In large surveys, people who played regularly had a lower risk of dementia and better mood.

Here's what they don't show. No one has proven that mahjong prevents Alzheimer's disease, and most of this research used Chinese mahjong with older adults, often people who already had memory problems. I'd be wary of anyone who promises more.

What the evidence does support is simple: a mind kept busy, in good company, on a regular schedule. That is exactly what a weekly game of mahjong offers. Next time, I'll break down the four kinds of memory you use every time you sit down to play.