A new reason to love your super-demanding job

April 2, 2014, 9:27 PM UTC

FORTUNE — So there you are as usual, spending your jam-packed workday making decisions, solving problems, evaluating new information, coming up with creative approaches to tricky situations, and setting strategy for your team. It’s what most managers do and, as stressful as it can get, all those constant demands on your brain turn out to have an upside: In later years, probably well into retirement, you may stay sharper mentally than people whose jobs are more routine.

That’s the conclusion of a new study from the University of Michigan Institute for Social Research, led by Gwenith Fisher, who teaches psychology at Colorado State University. Fisher says the research, based on data spanning 18 years, found that “certain kinds of challenging jobs have the potential to enhance and protect mental functioning later in life.”

In analyzing responses from 4,182 people who participate in the U-M Health and Retirement Study, which surveys a representative sample of more than 20,000 older Americans every two years, the researchers looked at eight different polls taken between 1992 and 2010, when the participants were between 51 and 61 years old. They worked in a variety of jobs and had been doing the same type of work for at least 10 years — about 25 years on average — before they retired.

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The researchers also looked at the “mental requirements” of each job those people reported having held, and tested their acumen on a variety of standardized tests designed to measure cognitive nimbleness, such as recalling a list of nouns immediately after seeing it and again after a delay, and counting backwards from 100 by sevens.

The results clearly showed that the more mentally challenging a person’s work before retirement, the more likely he or she was to maintain a high degree of mental sharpness, especially fewer and slower declines in memory, afterward. Moreover, the differences between people who retired from demanding jobs and those who’d had more routine occupations increased as time went on.

Does that imply that people with less complex and demanding jobs are doomed to suffer steeper, more rapid cognitive declines as they age? Not necessarily.

“What people do outside of work could also be a factor,” Fisher says. A stimulating hobby or interest could have the same beneficial effect on the cerebrum as challenging work — whether it’s learning a foreign language, studying astronomy, or taking a class in any unfamiliar subject. “Any time you are taking in new information, learning a new skill, or doing a new task, the brain benefits from that,” she notes. “The key is to be actively engaged and challenged mentally.”

The full study appeared in the March issue of the Journal of Occupational Health Psychology.