Puzzles and brain health in later life: what studies found

The Journal of the International Neuropsychological Society published a 2011 study of older adults who later developed dementia. Researchers asked these participants how often they had done crossword puzzles. Pillai and colleagues found that people who did crosswords later in life, whatever their level of education, tended to begin memory decline later.

The researchers based the finding on long-term observation of people. No one was required to solve puzzles by the researchers. Participants reported what they had done, and the researchers matched those reports against when memory decline began in the people who later developed dementia. Education was adjusted for in the analysis, so the link was not simply that people with more schooling did more crosswords.

Readers should look at what this kind of study actually measures. Two things were seen together: more crossword activity and a later start of memory decline. The study does not prove that solving puzzles caused the delay. People who keep solving crosswords into later life may differ from people who stop in ways the study did not capture, such as mood, how much they read, or how early their memory had already begun to change.

Two 2023 reports on mental activity

Researchers in a 2023 study on adult literacy and creative activities followed older people and learned how they spent their free time. The study found a nine percent lower risk of dementia among those who regularly engaged in mentally active activities, such as crossword puzzles, games, cards or chess. Participants in the group that performed these activities frequently played the games and puzzles regularly, while others did them rarely or not at all.

A second study published in JAMA Open in July 2023 found that older adults who regularly engaged in mentally challenging activities had a lower risk of developing dementia. The activities studied were journaling, playing chess and working on crossword puzzles. In the more active group, participants wrote in a journal, played chess or completed crosswords several times each week, while those in the less active group performed these activities infrequently.

Both reports compare groups of people by how often they performed these activities. In neither report were participants asked to start a new activity so that the outcome could be examined afterward. The numbers therefore show a pattern across many older adults, and they do not show what happens to one person who takes up crosswords.

Where observational results fall short

A 2018 study of 498 people born in 1936 asked whether working on crosswords or number grids kept older adults mentally sharp. The number grids followed a single rule: every row, column and box contained each number once. Doing crosswords or these grids did not stop age-related mental decline, the study found. The authors stated plainly that the study was observational, so it could not prove a causal effect.

In 2021, Wilson and colleagues reported a different result. Over 6.8 years they followed 1,093 older adults, comparing those who stayed active in cognitively stimulating activities with those who did less of them. Dementia began up to five years later in the group that kept up higher levels of stimulation.

In both studies, people's actions were observed and the effects on their memory and thinking were recorded afterward. Neither study assigned participants to a puzzle program or to a comparison group. Observational studies of this type can show whether an activity and an outcome occur together or not but they cannot prove that one causes the other. The two studies reached different conclusions about puzzles, and the design of each leaves the explanation open.

Small trials with no untrained group

NEJM Evidence published in 2022 a 78-week study that enrolled 107 adults with mild cognitive impairment. Two kinds of daily mental activity were compared in the study. Crossword puzzles were solved by one group, and computerized cognitive games were played by the other. The researchers were from Columbia University and Duke University.

The crossword group performed better on the ADAS‑Cog, a memory and cognition test, at both 12 weeks and 78 weeks. MRI scans also revealed less brain shrinkage in that group at 78 weeks.

In this trial participants were assigned to activities, which is a stronger design than the observational studies mentioned earlier. The trial still had no group that was left untrained. No participant was told to do neither crosswords nor computer games, so the results compare crosswords to the games. They do not show how much of the change came from crosswords alone, nor how a person who does no puzzles would have performed over the same 78 weeks.

The next step involves a test that puts crossword solvers next to people that do not solve puzzles at all.

NumFall is made by the publisher of this site. Any health or brain-training points here are general information, not medical advice.