Working a mentally stimulating job can actually help keep a person sharp well into his or her retirement.

Critical thinking, problem solving and planning are important intellectual requirements for a job that will keep a person's mind sharp even after they stop working, HealthDay News reported. Led by Colorado State University's Gwen Fisher, the study was published in the Journal of Occupational Health Psychology.

"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 told HealthDay.

Fisher said careers such as doctors, lawyers and project managers require a great deal of brain power, the stark opposite of a job like working an assembly line. In her study conducted with participants no younger than 51 and no older than 61, Fisher found that people with an intellectual challenge performed better on cognitive tests both before and after retirement.

"These results suggest that working in an occupation that requires a variety of mental processes may be beneficial to employees," Jessica Faul, a University of Michigan Institute for Social Research assistant scientist, said in a press release.

"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," she said. "Employers should strive to increase mental engagement at work and, if possible, outside of work as well, by emphasizing life-long learning activities."

Memory and other mental tests included recalling a list of nouns right after seeing and also after a time lapse, as well as counting back from 100 by intervals of seven. The study did not take formal education or income into account for the study and therefore could not distinguish who sought a mentally challenging job because of socioeconomic background.

"What people do outside of work could also be a factor," Fisher said in the release. "Some people may be very active in hobbies and other activities that are mentally stimulating and demanding, while others are not."