"Use it or lose it" is the wisdom received when it comes to cognitive ability. But is there any truth in this old look? Our latest research suggests that it depends on how much "it" you have to start with.
Previous observational studies, which examined the effect of performing mentally stimulating activities, such as puzzles, on cognitive ability, strongly supported the hypothesis of "using it or losing it." However, these studies were often based on screen shots in time – the so-called cross-sectional studies. To find out if there really is a connection between mental involvement over life and cognitive ability in old age, you need to follow people's habits and mental abilities throughout life.
For our study, reported in BMJ, we wanted to know whether mental commitment protects against cognitive decline, or if those with cognitive advantage engage more, giving the impression that this type of behavior is responsible for their superior abilities. To answer these questions, we had to work closely with our study participants and measure their intellectual abilities over and over again and compare their abilities to their performance at the beginning of life.
Scotland is unique because in 1947 almost all 11 year olds took the same mental aptitude test. The Scottish Council for Research in Education kept these records and in 1998 enabled us to contact the people who survived the test.
We tested individuals who live independently without dementia on up to five times over 15 years. Demographic, clinical, questionnaires, and psychological data were recorded in all assessments of performance changes on repeated tests of verbal and mental memory.
Our results are remarkable because they include intelligence data from a rare historical survey of intelligence. They showed that at a later stage, mental ability levels are closely related to current levels of involvement in problem solving.
Our study was able to explain intelligence and childhood education and found that the rate of decline in end-of-life cognition was not different among people who reported different levels of involvement. However, commitment levels were associated with entrance performance at the age of 64.
Childish intelligence is associated with intellectual interaction, which raises the question: Are smarter people more engaged, or are they smarter because they are engaged? If these were true at the end of life, we would expect some effect on the rate of decline.
We have shown that intellectual involvement in this group of people without dementia is not related to later rates of cognitive decline. But the commitment is related to intellectual gain acquired from childhood to late middle age when we began to examine them. In other words, making puzzles and other intellectually fascinating things for a lifetime improves your IQ so that when the inevitable cognitive decline sets in later life, you have a higher starting point. The rate of decline is the same for all, regardless of commitment levels.
At this stage, we can predict how intellectual engagement over life contributes to protection from falling below an intellectual threshold where it will be considered flawed. This is accomplished by starting from a higher point.
Our findings are consistent with similar studies following people older than 50. We have identified problem solving as being of particular importance. This suggests that interventions to increase aging resilience should include components for problem solving, such as reading complex novels, solving crossword puzzles and practicing musical instruments.
Roger Segal, Senior Lecturer in Respect and Aging, University of Aberdeen; Lawrence Whalley, emeritus professor of mental health, University of Aberdeen, And Michael Hogan, Senior Lecturer, Psychology, National University of Ireland
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