(HealthDay)—Jobs that make good use of your intellect might have another benefit down the line—a sharper mind long after retirement.
People with jobs that require problem solving, planning and information analysis appear more likely to retain a clear memory and keen reasoning as they grow older, said lead author Gwen Fisher, an assistant professor of psychology at Colorado State University.
"People who were engaged in work characterized as mentally challenging scored better on a measure of cognitive [thinking] ability, both before and after retirement," Fisher said.
Jobs that could give a person a mental boost later in life include "any job that involves gathering a lot of information and synthesizing it," she said.
Lawyers, financial analysts, teachers and doctors stand to benefit, but so will project managers who get a daily mental workout by juggling multiple assignments and guiding many employees, Fisher said.
On the other end of the spectrum are jobs that involve repetitive work without much variety or complexity, such as work on an assembly line, she said.
In the study, Fisher and her colleagues analyzed data from nearly 4,200 participants in the Health and Retirement Study, a federally funded survey conducted by the University of Michigan that tracks people as young as 51 prior to and following their retirement.
Participants are re-interviewed every two years, and the questions included measures of the mental demands of their jobs—analyzing data, developing objectives and strategies, making decisions, solving problems, evaluating information and thinking creatively. The survey also assessed memory and reasoning skills.
The people included in this study had been interviewed about eight times between 1992 and 2010. They worked in a large variety of jobs and on average had been employed in the same type of work for more than 25 years before retiring.
The investigators found that people who had jobs with greater mental demands were more likely to have better memories before they retired as well as slower declines in memory after retiring, compared to people in jobs that were less mentally stimulating.
Differences in memory at the time of retirement were not large, but they ended up doubling at 15 years following retirement, even after researchers controlled for factors such as education, health and economic status.
The study authors found similar results when they looked at questions used to assess mental impairment and dementia. By 15 years after retirement, people with mentally challenging jobs scored more than 50 percent better than people with less-demanding jobs.
The findings were published online recently in the Journal of Occupational Health Psychology.
This new study adds to a growing mound of evidence suggesting that people who want to keep their brain healthy after retirement need to start working their mental muscles earlier in life, said Keith Fargo, director of scientific programs and outreach for the Alzheimer's Association.
"It gels really nicely with other things we've seen where midlife is the point at which people really need to pay attention to their brain health," Fargo said.
There are a couple of theories why mentally challenging jobs might help preserve later brain capability, study author Fisher said.
By working the brain more, a person could end up creating more neurons during their years of employment, she explained. Later on, when age starts to take its toll, they will have more mental capacity and any loss of neurons will do less harm to their memory and reasoning.
There's also the "use it or lose it" hypothesis. "Much like muscles on our body, if you use the brain you strengthen it, and if you don't, it can atrophy," Fisher said.
But not everybody can have a mentally challenging job. To quote the movie "Caddyshack": "The world needs ditch diggers, too." Are those folks out of luck?
Not necessarily, both experts say.
"There are all kinds of things you can do to maintain your mental activity in midlife, outside of work," Fargo said.
Reading, playing games, volunteering for charity, socializing with friends, attending lectures and joining a book club are all activities that anyone can undertake to keep their brains active and give them a good workout, Fisher and Fargo agreed.
Such extracurricular activities could have influenced the study's findings, Fisher added, noting that the new research does not establish a direct cause-and-effect relationship between mental work demands and loss of memory or thinking ability after retirement.
"What people do outside of work could also be a factor," Fisher said. "Some people may be very active in hobbies and other activities that are mentally stimulating and demanding, while others are not."
Explore further: Studies: Memory declines faster in years closest to death
For more about loss of memory due to aging, visit the U.S. National Library of Medicine.