It has long been promoted as a way of staving off dementia for those heading into their twilight years.
Now scientists say doing puzzles even from a very young age could slash the risk of developing the condition.
A study found that children who were good at solving problems at eight years old kept these skills in later life.
Researchers said their findings suggest subtle cognitive differences could be a marker for dementia before the symptoms appear.
However, the results did not investigate whether cognitive skills in childhood are linked to the risk of developing dementia.
Education and income, assessed by occupation at the age of 53, was also shown to be an indicator of how brain power declines in your 70s.
The study is published in Neurology, the medical journal of the American Academy of Neurology, and was led by Professor Jonathan Schott.
Professor Schott, of University College London, said: ‘Finding these predictors is important.
‘If we can understand what influences an individual’s cognitive performance in later life, we can determine which aspects might be modifiable by education or lifestyle changes like exercise, diet or sleep, which may in turn slow the development of cognitive decline.’
His team followed 502 British people born during the same week in 1946 who took cognitive tests when they were eight – and again between the ages of 69 and 71.
There was a link between both sets of test scores – even though they were more than 60 years apart.
For example, someone whose cognitive performance was in the first 25 per cent as a child was likely to remain in the top quarter at 70.
Even accounting for differences in childhood results, there was an additional effect of education, with those who completed a college degree scoring around 16 per cent higher than peers who left school before the age of 16.
A higher socioeconomic status also predicted slightly better cognitive performance at 70 – those who had worked in ‘professional jobs’ tended to recall an average of 12 details from a short story, compared to 11 for those who had worked in manual jobs.
Overall, women performed better than men in tasks that challenged memory and thinking speed.
Professor Schott said: ‘The study also found childhood cognitive skills, education and socioeconomic status all independently influence cognitive performance at age 70.
‘Continued follow up of these individuals, and future studies, are needed to determine how to best use these findings to more accurately predict how a person’s thinking and memory will change as they age.’
The participants also underwent brain scans to look for amyloid-beta plaques – rogue proteins in the brain linked to Alzheimer’s.
The plaques collect between neurons and disrupt cell function, but it is not fully understood how.
Those who had the plaques performed worse on the tests. For example, they scored eight per cent lower on average in the ‘missing pieces’ test.
This involved looking at various geometric shapes and identifying the missing piece from five options.
Those with the amyloid-beta plaques got 23 out of 32 items correct on average in adulthood – two points fewer than participants without the clumps.
This suggests small differences in cognitive tests, potentially caused by amyloid plaques, are detectable years before dementia symptoms occur, Professor Schott said.
However, commenting on the study, Dr Ashok Jansari, of Goldsmiths, University of London, said: ‘There was no statistical difference in the scores of the adults who did show the plaques and who didn’t.’
The presence of the plaques was not connected childhood cognitive skills. Neither was it linked to sex, education or socioeconomic status.
Dr Jansari said: ‘Given that the plaques are the only current biological marker of Alzheimer’s, there is no relationship at all to be found here.’
Dr Matthew Iveson, a senior data scientist, University of Edinburgh, said: ‘The study does not claim that those performing poorly on the tests have, or will get dementia.
‘It just looks at performance on a battery of cognitive tests that may help to detect the subtle cognitive decline that precedes dementia.’
Dr Carol Routledge, director of research at Alzheimer’s Research UK which part funded the study, said one explanation for the link between childhood and adulthood brain power may be ‘cognitive reserve’.
It’s the idea that memory and thinking skills we acquire during our lives through education provides a resilience, known as cognitive reserve.
Research has shown that people with greater cognitive reserve are better able to stave off symptoms of degenerative brain changes seen in diseases like dementia.
‘But more research is needed to better understand this link’, Dr Routledge said.
‘This study sheds more light on the complex relationship between memory and thinking skills in early life and our cognitive ability as we get older.’
Dementia affects around 850,000 people in the UK – a figure set to rise to two million by 2050. In the US, it’s estimated there are 5.7million dementia sufferers.
With no cure in sight there is an increasing focus on identifying those most at risk to enable the adoption of preventative measures.
A limitation of the study is that all participants were white, so the results may not represent the general population.