People with challenging jobs may have to work hard, but the payoff could be some protection against Alzheimer’s disease later in life, new research suggests.

In a study of more than 10,000 older Swedish adults who were part of a twin registry, researchers found that people with a history of “complex” work had a lower risk of Alzheimer’s disease. The same held true even among twin pairs in which one was affected by Alzheimer’s but the other was not - a situation that factors in the influence of genes and upbringing.

The findings suggest that complex jobs may “provide some mental exercise” that helps delay the onset of dementia later in life, said the study’s lead author, Dr. Ross Andel of the University of South Florida in Tampa.

And that does not mean you need to be a rocket scientist, Andel told Reuters Health.

The study found that the complexity of a worker’s interactions with other people - with teaching as an example of higher complexity - showed the strongest link to a lower Alzheimer’s risk. Men and women with the most challenging jobs in this regard were 22 percent less likely to develop the disease compared with those with the least complex work.

These individuals also had a slightly lower risk of all forms of dementia, according to findings published in the Journal of Gerontology: Psychological Sciences.

The findings fit in with other research that has linked higher education, as well as mentally stimulating leisure activities like reading and doing crossword puzzles, to a lower risk of Alzheimer’s disease.

Although it’s not clear that these are cause-and-effect relationships, scientists speculate that people who stay mentally engaged throughout their lives may have a greater “cognitive reserve” that allows them to withstand more of the brain damage seen in Alzheimer’s disease before symptoms begin.

The physical-fitness principle of “use it or lose it” may apply, in a fashion, to the brain as well, Andel said.

His team’s study included 10,079 men and women from the Swedish Twin Registry who were at least 65 years old in 1998. Of these, 225 had been diagnosed with dementia, most (146 cases) had Alzheimer’s disease. There were 55 twin pairs who were discordant for dementia, meaning one was affected but the other was not.

Overall, people whose main lifetime occupation required more complex interpersonal relationships - such as managing people, making negotiations or dealing with customers - were less likely to have Alzheimer’s disease.

Among twins discordant for dementia, there was some evidence that complex work with data - compiling, organizing or analyzing information, for instance - was protective.

Complex work was related to lower Alzheimer’s risk regardless of a person’s education, the researchers found.

One of the strengths of the study, Andel said, was its separate analysis of twin pairs in which one had dementia and the other did not. Among these twins, the protective effect of complex work with people was even stronger than it was among the whole study population.

“This gives us more confidence that we’re really onto something,” Andel said.

SOURCE: Journal of Gerontology: Psychological Sciences, September 2005.