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Mental ability in early adulthood can predict later cognitive decline

A new study led by the University of California San Diego has found that general cognitive ability (GCA) in early adulthood is a much better predictor of future cognitive function compared to other factors, such as higher education or late-life intellectual activities.

General cognitive ability is a diverse set of thinking skills that are used for reasoning, memory, and perception. Prior research has linked activities such as reading, socializing, solving puzzles, and completing a higher level of education to a reduced risk of dementia, but the current study suggests that a measure of GCA provides a more accurate indication.

An international team of scientists set out to investigate based on an evaluation of more than 1,000 men participating in the Vietnam Era Twin Study of Aging. The participants, who are now in their 50s and 60s, had their GCA measured when they were an average age of 20 years old.

For the current study, the researchers analyzed the individuals using the same GCA measure. The team also explored seven different cognitive domains, including memory and abstract reasoning.

The study revealed that GCA at age 20 accounted for 40 percent of the variance in the same measure at age 62, and approximately 10 percent of the variance for each of the seven cognitive domains.

Compared to the GCA score at age 20, other factors had little effect. For example, lifetime education and engagement in intellectual activities each accounted for less than one percent of cognitive variance at the average age of 62.

“The findings suggest that the impact of education, occupational complexity and engagement in cognitive activities on later life cognitive function likely reflects reverse causation,” said study first author Professor William S. Kremen. “In other words, they are largely downstream effects of young adult intellectual capacity.”

Professor Kremen said remaining mentally active in later life is beneficial, but that the “findings suggest we should look at this from a lifespan perspective. Enhancing cognitive reserve and reducing later life cognitive decline may really need to begin with more access to quality childhood and adolescent education.”

The study is published in the journal Proceedings of the National Academy of Sciences.

By Chrissy Sexton, Staff Writer

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