It may sound counter-intuitive, but physically demanding jobs may raise the risk of dementia later in life.
For decades, the consensus has been regular physical activity shields the brain from degradation and keeps it clear of dangerous plaque.
However, a study in The Lancet found people who work in jobs that required medium to high physical activity, like salespeople – retail and other – nursing and care assistants, crop farmers and animal producers, have a greater risk of dementia or mild cognitive impairment (MCI), an early sign of the disorder.
Those who worked a ‘demanding’ job between the ages of 33 and 65 had a 72 percent higher risk of dementia and MCI in their 70s than people who had office jobs.
Physically demanding jobs are those that include climbing, lifting, balance, walking and stooping
Those who worked a ‘demanding’ job between the ages of 33 and 65 had a 72 percent higher risk of dementia and MCI in their 70s – the physical demands include climbing, lifting, balance, walking and stooping
While there was no definitive reason given for the increased risk, the study authors concluded the strain of physical labor required by high-demand jobs puts stress on the body and mind.
Greater physical demands, lack of downtime or time to recuperate and the 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 time standing, manual labor, stress, higher risk of burnout and a tough schedule, including rigid working hours and inconvenient working days.
These types of jobs can also put a person more at risk of hearing loss and exposure to pollution, both of which adversely effect cognition.
Additionally, individuals working in strenuous jobs may also differ in genetics and socioeconomic status, further confounding differences in cognition. Scientists propose that people with more physically demanding jobs may have had lower early-life cognitive abilities, which could have influenced their schooling and job opportunities.
A plausible explanation for the increased risk, scientists said, was that more physical demand later in adulthood has previously been linked to a smaller hippocampus and poorer memory performance.
The hippocampus is the part of the brain responsible for memory and learning and people working in demanding jobs have been found to perform worse on cognitive tests later in life.
Meanwhile, lower physically demanding jobs often include downtime for breaks, a more accommodating schedule and can include occupations such as engineering or teaching, which can be cognitively stimulating and lead to better cognitive development over time.
While previous studies on occupational physical activity and dementia have been limited and focused on occupation only close to a person’s retirement, this study gathers more data by looking at physical activity on the job over many years of a person’s adult life.
Approximately seven million people in the US and one million people in the UK have a type of dementia.
Dr Vegard Skirbekk, study author and professor of Population and Family Health at Columbia Public Health, said: ‘Our findings extend those from previous studies by incorporating a life-course perspective into research on occupational physical activity and cognitive impairment.
‘Whereas previous studies have also mainly focused on a single measurement of occupation, we include occupational trajectories from ages 33–65 to give a broader picture of the occupational histories of the participants and how these relate to risk of cognitive impairment in later adulthood.’
Researchers analyzed data from one of the world’s largest population-based studies of dementia, the HUNT4 70+ Study, which collected data from 2017 to 2019 of adults in Norway.
It included 7,005 people aged 33 to 65 years old and assessed the association of the risk of dementia when they were 70 years and older.
Ninety-two people in the study were clinically diagnosed with dementia and 2,407 were diagnosed with MCI.
Researchers say their study indicates the importance of developing strategies for people in physically demanding jobs that can prevent cognitive impairment later in life.
Despite this study’s findings, it is in contradiction to another recent study that found the opposite – that the risk of dementia actually increases among adults who spend more than 10 hours per day engaging in sedentary behaviors.
The study, conducted by the Norwegian National Centre of Ageing and Health and Columbia Mailman School of Public Health and the Butler Columbia Aging Center, was published in The Lancet Regional Health – Europe.
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