'Use it or lose it' might not be backed by science but don't give up Sudoku just yet

A recent study found intellectual pursuits are unlikely to stave off mental decline – but that shouldn't deter enthusiasts from sharpening their cognitive skills

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In common with many people of a certain age, my father took up Sudoku after a friend persuaded him it was “scientifically proven” that it would help slow down memory loss. He believed problem-solving activities could be instrumental in slowing down the effects of cognitive ageing and dementia.

The idea of "use it or lose it" is a common one among the elderly when it comes to cognitive functions, a hypothesis that is often touted by healthcare professionals and psychological experts. Previous studies have suggested cognitive ability can be exercised and even improved by gentle mental pursuits such as crossword puzzles and mathematical challenges like Sudoku.

However, my father will no doubt be dismayed by the findings of a recent study by a team at Aberdeen Royal Infirmary and the University of Aberdeen in Scotland. They embarked on research to find out whether there was a link between intellectual pursuits and cognitive ability later in life. The team tested nearly 500 participants over a 15-year period and found while those who indulged in intellectual hobbies regularly had a higher mental ability, such habits had no impact on the rate of cognitive decline associated with ageing.

However, while turning to the back page of this newspaper to fill in that word search might not keep you mentally agile for longer, doing so regularly – and from a young age – does seem to provide a “higher cognitive point” from which the decline takes place. In short, the brighter you are and the sharper your mind throughout your life, the more capable you are likely to be in your sunset years when the decline first begins.

The key is to start early. I was delighted, therefore, when one of my school-age daughters became a big fan of Sudoku. But even so, things are far from straightforward. A randomised controlled experiment published five years ago by a group of scientists at Johns Hopkins Bloomberg School of Public Health looked at the longitudinal effects of multiple sessions of memory, speed of processing and reasoning, focusing on a sample of 2,832 individuals from six US cities. The study found that while reasoning and speed of processing remained consistent over a decade, the same could not be said for the performance of their memories.

And whether activity engagement benefits cognitive functions in later life is still being debated. The Scottish study, published last month in the British Medical Journal, is one of the longest-running surveys of cognitive function data aiming to shed new light on this question. It took as its sample group people born in 1936, who had taken part in an intelligence test at the age of 11. The Scottish team regrouped them at the age of 64 and began testing them repeatedly over a 15-year period.

They were presented with questionnaires testing them on their ability to evaluate information, the speed of their mental processing and memory. The results indicated benefits when individuals engaged early on in life in intellectually stimulating activities but found no significant effect on cognitive decline.

This does not mean that doing crosswords, Sudoku or playing chess are activities that do not have benefits for our cognitive abilities. We should not abandon the head-scratching pleasures of problem-solving activities in favour of binge-watching television instead. Far from it.

Because isn’t the idea of significant cognitive gains over the course of a lifetime far more appealing? I fully embrace the report’s findings that “investment in intellectual activities throughout life could provide a higher cognitive point from which to decline”.

In other words, cognitive decline or neurodegenerative diseases might be beyond our control but the more mentally capable we are when it begins, the better.

In that light, the Beatles song When I'm Sixty-Four, in which John Lennon and Paul McCartney wrote of "wasting away…when your lights have gone" need not be a reality.

Professor Olivier Oullier is the president of Emotiv, a neuroscientist and a DJ