July 8, 2008
Having a mentally stimulating job that challenges the intellect may help to keep the mind sharp into old age, a new study shows. And the more challenging and complex the job, the better memory and thinking skills may hold up after retirement.
The findings are consistent with earlier research suggesting that to keep the brain fit, it's important to "use it or lose it." Just as muscles must be exercised to keep them strong, so the brain must be kept stimulated to keep it humming.
Keeping the brain active through challenging mental activities like doing crossword puzzles, learning a new language or remaining engaged in an intellectually stimulating job or hobby, the thinking goes, keeps brain cells in peak condition. Letting those brain challenges flag, on the other hand, may contribute to weakened brain cell function and, ultimately, Alzheimer's disease.
"Our society expects us to live and work longer than previous generations, so we sought to understand how an individual's occupation affected cognition later in life," said study leader Guy Potter, an assistant professor of psychiatry at Duke University Medical Center. He and his colleagues studied 1,036 male twins, most of them World War II veterans.
Looking at old army medical files, the researchers obtained data on their IQ scores when they joined the army, nearly 50 years earlier. They then compared the data with mental test scores taken every three or four years after the men had retired from various careers.
The scientists found that men who scored in the bottom one-quarter in IQ scores in their youth but who went on to intellectually challenging careers had the greatest gains in cognitive skills by the time they reached their 60s and 70s. It was as if the demands of a complex job later in life helped to build intellectual "muscle" that kept the brain relatively sharp into old age. Those who scored highly on IQ tests early in life also showed benefits from a mentally demanding job, though the gains were relatively more modest.
The jobs that proved most beneficial to these men included professional careers like law, medicine and journalism. Any job that required complex organization, decision-making, multi-tasking and management duties also boosted brain function later in life.
"Although the intellectual and physical demands of an individual's job are not the largest factors influencing cognitive performance as we age, this study illustrates how a number of smaller influences like these can accumulate over the life span to have a positive or negative effect on brain health in later life," Dr. Potter said. "Unlike age or intellect, job demands are something that an individual can potentially modify to optimize their cognitive reserve."
"Most of us spend a significant portion of our adult life at work, and we may actually be benefiting from the intellectual demands placed upon us," Dr. Potter added.
Guy G. Potter, PhD, Michael J. Helms, BS and Brenda L. Plassman, PhD: "Associations of job demands and intelligence with cognitive performance among men in late life." Neurology, Volume 70, May 2008, pages 1803-1808.