Does sudoku help
your brain?

Sudoku has less research behind it than crosswords, but it has one very large study, and the result is the same shape: people who do number puzzles more often think more sharply, with the usual caution that this is an association rather than proof of cause.

What the 19,000-person study found

The PROTECT study asked 19,078 cognitively healthy adults aged 50 to 93 how often they did number puzzles such as sudoku, on a scale from more than once a day to never, and tested them on attention, reasoning, working memory and episodic memory.^[1] The pattern was graded: the more often people did number puzzles, the better they scored, on every test. Frequent number puzzlers performed like people about eight years younger on measures of grammatical reasoning and short-term memory. The companion analysis of word puzzles found the same relationship.^[2]

Why that is not the end of the story

PROTECT measured habits and cognition at one point in time. Sharp people may enjoy sudoku more, stick with it longer, and score well for reasons that have nothing to do with the puzzle. The researchers adjusted for age, sex and education, which helps, but it cannot rule out that the arrow runs from cognition to puzzling rather than the other way. The authors were clear that a trial would be needed to settle it, and none has been done for sudoku.

The wider brain-training literature suggests what such a trial would probably find: sudoku practice makes you better at sudoku and perhaps at closely related logic tasks, with modest and specific transfer at best.^[3] The one form of cognitive training with a demonstrated ten-year effect, speed-of-processing training in the ACTIVE trial, is quite unlike sudoku.^[4]

What sudoku exercises

A sudoku grid asks you to hold several constraints in mind at once, scan systematically, eliminate candidates and notice when a single possibility remains. That is working memory, sustained attention and deductive reasoning. It is not arithmetic; the digits are just labels. People who want to practise mental calculation are better served by a timed arithmetic trainer, and people who enjoy the rule-finding side of number puzzles may prefer sequences, which Brisk serves two of each day as its brain teaser of the day.

A fair summary

Frequent number puzzling is associated with better attention, reasoning and memory in a very large sample of adults over 50. Cause has not been established and prevention of any disease has not been shown. Sudoku is an engaging, low-cost way to spend ten minutes on deduction, and that is reason enough to do it.