It may seem counterintuitive, but physically demanding jobs can increase the risk of dementia later in life.
For decades, the consensus has been that regular physical activity protects the brain from breakdown and protects it from dangerous plaques.
However, a study published in The Lancet found that people who work in jobs requiring moderate to high physical activity, such as salespeople (retail and other), nurses and caregivers, farmers and livestock breeders animals, are at higher risk of dementia or mild cognitive impairment (MCI), an early sign of the disease.
Physical demands of the job include climbing, lifting, balancing, walking and stooping.
Those who held a “demanding” job between the ages of 33 and 65 had a 72% higher risk of dementia and MCI in their 60s than people with low physical activity.
The risk of dementia and MCI among people aged 70 and over who worked in demanding jobs was 15.5 percent, compared to a risk of 9 percent among those who worked in less physical work.
Physically demanding jobs are those that include climbing, lifting, balancing, walking, and stooping.
Those who worked in “demanding” work between the ages of 33 and 65 had a 72% higher risk of dementia and MCI at age 70 – physical demands include climbing, lifting weights, balancing, walking and stooping.
Although no definitive reason was given for this increased risk, the study authors concluded that the physical labor required by high-demand jobs puts strain on the body and mind.
Increased physical demands, lack of downtime or time to recover, and resulting exhaustion can lead to “wear and tear” on the body and mind, which could collectively worsen cognition.
Additionally, the occupations studied often include long periods of standing, manual labor, stress, a higher risk of burnout, and difficult schedules, including rigid work schedules and inconvenient work days.
These types of jobs can also put a person at increased risk of hearing loss and exposure to pollution, both of which harm cognition.
Additionally, individuals working in strenuous jobs may also differ in genetics and socioeconomic status, further confounding differences in cognition. Scientists suggest that people in more physically demanding jobs may have had lower cognitive abilities earlier in life, which could have influenced their education and employment opportunities.
A plausible explanation for this increased risk, the scientists say, is that greater physical demand later in adulthood was previously linked to a smaller hippocampus and poorer memory performance.
The hippocampus is the part of the brain responsible for memory and learning and it has been found that people working in demanding jobs perform worse on cognitive tests later in life.
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Meanwhile, less physically demanding jobs often include downtime for breaks, a more accommodating schedule, and may include occupations such as engineering or teaching, which can be cognitively stimulating and lead to better cognitive development over time.
While previous studies on physical activity at work and dementia have been limited and focused on occupation only as a person nears retirement, this study gathers more data by examining physical activity at work over many years of a person’s adult life.
Around seven million people in the United States and one million people in the United Kingdom have some type of dementia.
Dr. Vegard Skirbekk, study author and professor of population and family health at Columbia Public Health, said: “Our findings extend those of previous studies by integrating a life course perspective into research on Occupational physical activity and cognitive impairments.
“While previous studies have also primarily focused on a single measure of occupation, we include occupational trajectories aged 33 to 65 to provide a broader picture of participants’ employment histories and how they relate to risk of cognitive impairment in later adulthood.”
The researchers analyzed data from one of the world’s largest population-based dementia studies, the HUNT4 70+ study, which collected data from 2017 to 2019 on adults in Norway.
It included 7,005 people aged 33 to 65 and assessed the association of dementia risk when they were 70 and older.
Ninety-two people in the study were clinically diagnosed with dementia and 2,407 were diagnosed with MCI.
The researchers say their study indicates the importance of developing strategies for people in physically demanding jobs that can prevent cognitive impairments later in life.
Despite this study’s findings, it contradicts another recent study that found the opposite: dementia risk actually increases among adults who spend more than 10 hours a day engaging in sedentary behaviors.
THE studyconducted by the Norwegian National Center for Aging and Health, the Columbia Mailman School of Public Health and the Butler Columbia Aging Center, was published in The Lancet Regional Health – Europe.