Men who work in manual labour jobs may be more likely to develop dementia, controversial research suggests.
Dementia is an umbrella term for a range of conditions that cause a decline in brain function, with Alzheimer’s being the most common.
Exactly why it occurs is often unclear, however, the NHS states an individual can reduce their risk by maintaining a healthy lifestyle, with plenty of exercise.
Scientists from the University of Copenhagen have found, however, intense physical labour may be detrimental.
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The team analysed more than 4,000 men across 14 companies. Results suggest those who worked in hard physical occupations were up to 55% more likely to later develop dementia than the men in the most sedentary roles.
Although unclear, it has been suggested the muscles and joints may not be the only parts of the body worn down by intense manual work, with the brain potentially also being affected.
Dementia affects 850,000 people in the UK, a figure that is expected to rise to 1.6 million by 2040.
Physical activity is often said to help protect someone from dementia, with a separate University of Copenhagen study finding a healthy lifestyle can halve a person’s risk.
To better understand dementia’s cause, the team analysed participants of the Copenhagen Male Study, which collected information on the men’s occupation during the 1970s, when they were aged 40 to 59.
The men worked in a variety of professions, from a railway company and the Danish defence to postal services and the government.
The results, published in the Scandinavian Journal of Medicine & Science in Sports, suggest those who worked in the most labour intensive jobs were up to 55% more likely to develop dementia than their more sedentary counterparts.
This remained true after adjusting for other lifestyle factors that influence a person’s dementia risk, like smoking, alcohol consumption and high blood pressure.
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“The WHO [World Health Organization] guide to preventing dementia and disease on the whole mentions physical activity as an important factor,” said study author Dr Kirsten Nabe-Nielsen.
“But our study suggests it must be a ‘good’ form of physical activity, which hard physical work is not.
“Guides from the health authorities should therefore differentiate between physical activity in your spare time and physical activity at work, as there is reason to believe the two forms of physical activity have opposite effects.”
Previous research has suggested hard physical work may have a negative effect on the heart, blood and circulation, contributing to conditions like high blood pressure, clots in the heart and even heart failure.
Dementia has been linked to high blood pressure. Reduced blood flow to the brain can also starve the cells of the oxygen and nutrients they need to function.
The scientists stressed prevention is critical, with the brain often being damaged before symptoms come to light.
“A lot of workplaces have already taken steps to improve the health of their staff,” said co-author Professor Andreas Holtermann.
“The problem is it is the most well-educated and resourceful part of the population that uses these initiatives.
“Those with a shorter education often struggle with overweight, pain and poor physical fitness, even though they take more steps during the day and to a larger extent use their body as a tool.
“For workmen, it is not enough, for example, to avoid heavy lifts if they wish to remain in the profession until age 70.
“People with a shorter education doing manual labour also need to take preventive steps by strengthening the body's capacity via for example exercise and strength training.”
The scientists are investigating interventions that could help ease the negative impact of manual labour.
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