Games like Lumosity and CogniFit are designed to keep your brain mentally fit. Whether they work or not — some experts claim the benefits are overstated — is a whole other can of worms. Researchers from the University of Michigan now argue that just picking a mentally demanding job is enough to keep your brain healthy and strong long after retirement.

A wealth of research has already shown that cognitive decline most easily accelerates when the brain is unstimulated. Given the advances in medical science, people are living longer around the world, leading to Alzheimer’s Disease International’s estimates that dementia cases will triple by 2050. Now Michigan scientists argue stopping that decline, and the slow erosion that precedes it, could be accomplished through your line of work.

"Based on data spanning 18 years, our study suggests that certain kinds of challenging jobs have the potential to enhance and protect workers' mental functioning in later life," said Gwenith Fisher, researcher at the University of Michigan Institute for Social Research and assistant professor of psychology at Colorado State University, in a statement. These jobs require critical thinking, creativity, problem-solving, analysis, and tough decision-making.

Fisher and her colleagues collected data on 4,182 participants in the U-M Health and Retirement Study, which surveys more than 20,000 older Americans every two years to learn about their lives before and during retirement. Participants were interviewed roughly eight times between 1992 and 2010, beginning between 51 and 61 years old, and having completed, on average, 25 years of work.

In addition to looking at the various duties each respondent performed at his or her job, the research team had participants perform several tests, each designed to shine a light on their cognitive state. One test involved repeating a list of 10 nouns immediately after seeing it, while another had participants count backward from 100 in intervals of seven. Researchers controlled for mental and physical health, economic status, and demographic factors including years of education. They didn’t take activities outside of work into account.

Overall, their results suggested that employees who carry a heavier cognitive load, one that is varied and frequently stimulated, may enjoy richer years in old age. "It's likely that being exposed to new experiences or more mentally complex job duties may benefit not only newer workers but more seasoned employees as well,” Fisher explained. She added that employers would do well to maximize employee engagement, both in and out of work.

One limitation to the study is in its direction. Fisher and her team concede that a causal relationship can’t be established, only inferred. It may be the case, for example, that people with greater cognitive functioning simply fill more demanding jobs. However, the team did control for education levels and income, which add weight to the causal side.

"What people do outside of work could also be a factor," Fisher concluded, adding that “some people may be very active in hobbies and other activities that are mentally stimulating and demanding, while others are not."

Source: Fisher G, Stachowski A, Infurna F, et al. Mental Work Demands, Retirement, and Longitudinal Trajectories of Cognitive Functioning. Journal of Occupational Health Psychology. 2014.