Are physically-demanding jobs a risk for dementia?

Nursing is one of the occupations that might be at higher risk of developing dementia, due to its physical demands. — AFP

The job you do could influence your cognitive decline in old age, according to an international team of researchers.

They reveal that jobs involving medium or high levels of physical activity are associated with an increased risk of cognitive impairment and dementia.

The researchers from the Norwegian National Centre of Ageing and Health, as well as the Columbia Mailman School of Public Health and the Butler Columbia Aging Center in the United States, looked at the possible association between occupations exercised during working life, more specifically between the ages of 33 and 65, and the development of cognitive disorders from the age of 70 onwards.

Published in the journal The Lancet Regional Health – Europe, the study analysed 7,005 people, 2,407 of whom developed mild cognitive impairment and 902 of whom developed some form of dementia.

Previous studies have looked at this subject, but focused only on “a single measurement of occupation”, and not on the participants’ occupational history over a period of more than three decades.

This is an important detail, given that the silent phase of dementia can begin up to 20 years before symptoms appear.

This research suggests that having a job that involves a certain level of physical activity, i.e. of a medium to high level, is associated with an increased risk of cognitive impairment.

In detail, the risk of dementia and mild cognitive impairment was 15.5% for participants who had a physically-demanding job in the latter part of their working life, compared to 9% for those whose job required little or no physical activity.

These findings could ultimately lead to the development of new strategies to limit these effects.

“It is critically important to understand how workplace physical activity levels relate to cognitive impairment and dementia.

“Our work also highlights what is called the physical activity paradox, i.e. the association of leisure time physical activity with better cognitive outcomes, and how work-related physical activity can lead to worse cognitive outcomes,” said study author and population economist Professor Dr Vegard Skirbekk in a news release.

Numerous studies have demonstrated the benefits of exercise, and physical activity in general, on mental health and cognitive function.

In an article dating from 2019, the French Brain Research Foundation explained that exercising could induce “an improvement in cognitive abilities, and ... could even protect against certain brain pathologies such as neurodegenerative diseases and depression”.

At the time, however, the focus was on physical activity during leisure time, not as part of a professional activity.

Examples of occupations subject to moderate to high levels of physical activity provided by the study authors include salespeople, nurses, care workers and farmers.

All of these jobs are subject to numerous physical inconveniences, including prolonged standing, extended or staggered working hours, and tasks that are difficult to perform, as the researchers point out.

“Future research should assess how occupational physical activity and interventions to reduce occupational physical activity or technological changes leading to altered activity, in combination with other characteristics of the job, relate to dementia and mild cognitive impairment risk in older ages.

“This will further our understanding of the association between occupational histories and cognitive impairment,” concludes Prof Skirbekk. – AFP Relaxnews