A widely held belief has it that the more we use our brains, the less likely it is that we will experience mental decline as we age, but to what extent is this notion true?
As we get older, our bodies and minds begin to lose their suppleness slowly. This is a normal effect of aging, though sometimes, the decline can be steeper and related to neurodegenerative conditions.
Existing research has suggested that people can prevent age-related mental decline if they take certain actions, one of the most important being training one's brain by challenging it through puzzles and similar problem-solving activities.
How true is this idea? In a new, longitudinal study, researchers from the University of Aberdeen and the National Health Service (NHS) Grampian in Aberdeen — both in the United Kingdom — in collaboration with colleagues from the National University of Ireland in Galway address this question.
The research team was led by Dr. Roger Staff, who is an honorary lecturer at the University of Aberdeen, and head of medical physics at Aberdeen Royal Infirmary.
"Activity engagement is so often argued to be an important dimension of successful aging (and more specifically, the preservation of intellectual function in old age) that the 'use it or lose it' conjecture already appears to be an established fact of cognitive aging," the research team writes in the study paper, which appears in The BMJ.
"We aimed to re-examine this claim by analyzing the effects of activity engagement on cognitive test performance and the trajectory of that performance in late adulthood," the investigators explain.
Impact or no impact?
The researchers analyzed the data of 498 participants who were all born in 1936 and had taken an intelligence test — The Moray House Test — when they were 11 years old, as part of the Scottish Mental Survey of 1947. The team collected this information through the archives of the Scottish Council for Research in Education, which holds records of the Scottish Mental Survey.
At the beginning of the current study, the participants were around 64 years old and had provided information about their educational history and mental abilities at baseline.
They all agreed to undertake additional tests, assessing memory and mental processing speeds, as well as other measurements of cognitive function, on up to five different occasions over the following 15 years.
These included digit symbol substitution tests, auditory-verbal learning tests, and assessments measuring the participants' interest in reading and problem solving, their critical thinking, and intellectual curiosity.
After accounting for potential modifying factors, the investigators found that problem-solving activities did not impact the rate of age-related mental decline. However, regularly engaging in such activities did appear to improve a person's cognitive skills throughout their life.
This also meant that people who liked to undertake problem-solving tasks — such as doing crosswords, solving puzzles or sudoku problems — did have better mental abilities in late life.
'A higher starting point' for decline
According to Dr. Staff and team, the study's findings suggest that, while it may not halt age-related cognitive decline altogether, problem-solving can keep the brain in better shape earlier in life, so that mental decline may not be so noticeable later on. The researchers write:
"These results indicate that engagement in problem-solving does not protect an individual from decline, but imparts a higher starting point from which decline is observed and offsets the point at which impairment becomes significant."
At the same time, however, the investigators note that this was an observational study, so we must be cautious when it comes to inferring a cause and effect relationship. Factors other than regular problem-solving, such as an individual's personality, may contribute to improving their cognitive skills during their life.
"Personality could govern how much effort older people put into such activities and why," the researchers write, adding that, "How personality and mental effort are related and how their combined influence affects cognitive performance is unclear."
Future studies, the researchers say, should investigate these unanswered questions and aim to replicate the current findings. Still, they stress how important it is for people to stay curious and keep on training their brains through challenging activities.
"[For] those of you struggling to come up with good ideas for Christmas presents for the 'developing' adults in your life — although a shiny new chess board, 1,000-page Sudoku puzzle book, or all-inclusive tickets to the museum of modern art's quiz night might not influence trajectories of cognitive decline, have no fear," the researchers write at the end of their paper.
"If family and friends give you a disappointed look on opening their Christmas present, remind them that investment in intellectual activities throughout life could provide them with a higher cognitive point from which to decline," they encourage.