“When we look at the association between complexity of work with people or data, we see that those in more complex jobs generally do better on a range of cognitive ability measures,” said Alan Gow, one of the study authors.

“That’s not necessarily surprising . . . but we were able to add an interesting twist,” said Gow, an assistant professor of psychology at the School of Life Sciences at Heriot-Watt University in Edinburgh, Scotland.

The researchers knew from earlier work that complex jobs might help protect cognitive ability later in life. So they added the childhood IQs of 1,066 people in Scotland from a 1936 study to their analysis.

They also grouped the people from that study according to profession - for example, architect, engineer and lawyer (higher thinking jobs) or typist and salesperson (requiring less complicated thinking).

The study participants, all age 70 during the new analysis, took cognitive tests that determined general thinking ability, speed and memory. Their educational and criminal backgrounds and access to services were also factored in.

By including data on IQ from the participants when they were 11 years old, “the association between more complex jobs and better cognitive outcomes is reduced, but there remains a small additional benefit for our cognitive abilities from being in more complex jobs,” Gow told Reuters Health in an email.

Childhood IQ explained about half of the difference in later thinking ability in the participants. And complex jobs were responsible for about 1 to 2 percent of the cognitive differences between people later in life, according to the results in the journal Neurology.

The researchers said the cognitive benefit of a complex job was similar to the benefits of not smoking on later cognition.

“It’s been proposed, for example, that more complex work with people and data might require the deployment of various cognitive abilities; this may develop these skills, or at least protect them from decline, and people are exploring what those suggested mechanisms might actually look like in terms of changes in the brain,” Gow said.

He's been looking at a variety of lifestyle factors that might predict cognitive ability in older people, including leisure and physical activity and social networks and support.

“The reason I focus on factors like these is that many, though not all, of course, are amenable to change. If we can identify the things that protect or harm our cognitive abilities, we will be able to provide clear information or design better interventions,” Gow said.

“I think the opportunity to use our thinking and reasoning skills and continually use them throughout our lives likely contributes to our ability to stay sharp,” said Sian Beilock, a psychology professor at the University of Chicago.

“So being able to do complex thinking and reasoning in our profession is one way to continually flex our cognitive horsepower or brain power,” said Beilock, who was not involved in the study.

Other ways to ward off cognitive decline include exercise, and remembering our strengths, rather than dwelling on what we’re forgetting, he said.

“Doing things to get rid of those worries, whether reminding yourself you have lots of experience or jotting down things (like worries) in notes . . . can help ensure you can use all the brain power at your disposal,” Beilock said.