Mild cognitive impairment, dementia risk tied to physical jobs

• People with a consistently high level of occupational physical activity are more likely to develop dementia or mild cognitive impairment, says a new study.
• The authors of the study call for the development of cognitively protective strategies for people in such jobs.
• People in jobs with an intermediate amount of physical activity are at greater risk of mild cognitive impairment. This can often lead to dementia.

If your job involves a high level of physical activity, you may be at an increased risk of dementia or mild cognitive impairment (MCI), suggests a new study, published in The Lancet Regional Health – Europe.

People with a high level of occupational physical activity have a 15.5% risk of dementia, compared to the 9% risk for people whose work involves a low level of physical activity, says the study.

The study also found that people whose work requires an intermediate level of occupational physical activity are at higher risk of mild cognitive impairment, but not dementia, per se.

The study is an analysis of data from the fourth, 2017–2019 wave, of the HUNT4 70+ Study, one of the largest collections of dementia data. It included 7,005 people living in the county of Trøndelag in Sweden, aged 33–65. Of the study participants, 49.8% were women.

The authors define occupational physical activity as ”[p]erforming physical activities that require considerable use of your arms and legs and moving your whole body, such as climbing, lifting, balancing, walking, stooping, and handling of materials.”

They rated occupational physical activity on a scale of one to five, with one representing the least amount of such activity, and five the most.

Some of the most common occupations among study participants with exposure to intensive physical activity in their roles were retail, nursing and care, and farming.

A life-course perspective on dementia risk

The study’s corresponding author, Dr. Vegard Skirbekk, explained to Medical News Today that the purpose of the study was to better understand the risks for Alzheimer’s disease and related dementias over the course of one’s life.

“Understanding [Alzheimer’s disease and related dementias] risks in a life-course perspective may be important for both the general public and health service providers. The causes of dementia late in life could plausibly be found earlier in life,” said Dr. Skirbekk.

Dr. Roseanne Freak-Poli, a life-course epidemiologist and senior research fellow at Monash University in Australia, not involved in this research, endorsed the study’s life-course approach, saying it provides a “more comprehensive understanding of how occupational histories affect cognitive health.”

As it is, she noted, “we know that the physical activity intensity of our jobs is likely to decrease as we get older, so looking across the life course provides a better understanding than measurement at just one time point.”

Brain health coach Ryan Glatt, director of the FitBrain Program at the Pacific Neuroscience Institute, also not involved in the research, said he was most interested in the study’s finding regarding the link between intermediate occupational physical activity and MCI.

As to why people with intermediate occupational activity are more likely to experience MCI, Dr. Skirbekk said: “We believe that it is to a large extent a matter of degree; the greater the physical strains, the higher the risks later in life.”

“Whether that is MCI or dementia, I don’t think this article is sensitive enough to determine,” observed Glatt. “This is a very large survey. It’s just kind of a signal.”

Co-factors potentially at play

The researchers considered education, income, marital status, health, and lifestyle-related factors in their analysis.

“I think what this really might be signaling is a relationship between what kinds of people and which sociodemographic statuses are working these types of jobs,” Glatt told us.

The authors themselves write that “the association between occupational [physical activity] and late-life cognitive impairment could be confounded by differences in socioeconomic status.”

In addition, asked Glatt: “Is it possible that more physically demanding jobs, let’s say construction work, could be more stressful? Yeah, absolutely. Is there a likelihood of maybe exposure to certain environmental toxins in certain jobs that might have physical activity possibly?”

Can people in physically intensive jobs lower their dementia risk?

“I don’t think I could just go up to someone and say, ‘Hey, I think you should find a desk job because this job is going to give you dementia,’” said Glatt.

So, what can a person with a physically demanding job do to protect their cognitive health?

Dr. Skirbekk said, “we believe that when one has autonomy and can take breaks, as well as having a sense of control over one’s physical demands, may lower risks.”

Meanwhile, Dr. Skirbekk added, following standard advice for dementia risk factors makes sense: “Avoid smoking, excessive alcohol intake, social isolation, [prevent or treat] high [blood pressure], diabetes, depression, [avoid] physical inactivity, use hearing aids in case of hearing impairment, and reduce exposure to air pollution.”

Glatt suggested making sure one gets structured exercise on their time off, even if their job is physically demanding. He recommended aerobic exercise, strength training, and neural motor exercise.

Sleep, he said, is also critical to cognitive health: “A lot of people have theorized and have researched that when individuals are more physically and cognitively active, it increases the hunger and the drive for sleep.”

It is also the case, he said, that this study is part of larger conversations we need to be having. “Occupational risks are really interesting, environmental exposures are interesting, job stresses are interesting: the relationship between what’s good about a job, and what’s bad about a job.“

He called for “more occupational research on what kinds of jobs contribute to longevity, as well as health outcomes.“

“And I think if we are able to understand the relationships between those factors better — such as physical activity and stress and cognitive activity — I’m hopeful we can understand yet another factor of what might contribute to someone’s brain health journey.“

– Ryan Glatt

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