The Conundrum of Physical Work: Correlation with Cognitive Decline Uncovered in Recent Research

A novel investigation has revealed that a career’s worth of high physical exertion on the job is linked to an increased likelihood of experiencing cognitive decline in later years. This study builds upon prior research by adopting a longitudinal approach, examining work-related physical activities from the age of 33 until 65, and its consequent effects on cognitive capabilities beyond 70 years of age. The research included more than 7,000 subjects, and found that individuals with labor-intensive careers faced a 15.5% chance of cognitive difficulties, in contrast to a 9% chance for those with jobs requiring less physical labor. These outcomes highlight the urgent need for strategies to alleviate dementia risks in such labor-intensive professions.

The Norwegian National Centre of Ageing and Health, in collaboration with the Columbia Mailman School of Public Health and the Butler Columbia Aging Center, has identified a pattern linking ongoing physical exertion in moderate to high-intensity jobs with an elevated risk of cognitive degradation.

The implications of this study emphasize the importance of devising protective measures for workers in strenuous jobs to shield them from cognitive decline. The study’s results were recently presented in The Lancet Regional Health – Europe journal.

The Paradox of Physical Activity

“The relationship between the level of physical activity at work and the subsequent onset of cognitive impairment and dementia is of paramount significance,” stated Vegard Skirbekk, PhD, a professor at Columbia Public Health. He points out the ‘physical activity (PA) paradox,’ which refers to the beneficial cognitive effects linked with physical activity during leisure time, as opposed to the adverse cognitive impacts associated with physical labor.

Research Techniques and Background Studies

Previous research into the link between occupational physical activity and dementia was not extensive. Historically, studies have focused on a single point within an individual’s career, often near the point of retirement, and primarily relied on self-reported data.

“By integrating a life-course viewpoint, our study expands on the results of earlier research concerning work-related physical activity and cognitive decline,” Skirbekk explained. Instead of focusing on a single career stage, this study tracks occupational physical activity from the ages of 33 to 65, offering a comprehensive view of the participants’ job histories and their relation to cognitive decline risk in their later years.

Skirbekk notes that dementia’s preclinical phase could begin up to twenty years before symptoms become apparent. Hence, considering various occupations over one’s career may yield more precise insights into the intricate dynamics between job characteristics and cognitive impairment.

Research Outcomes

The research utilized data from one of the world’s largest population-based dementia studies, the HUNT4 70+ Study, to evaluate the correlation between occupational physical activity from ages 33 to 65 and the risk of dementia and mild cognitive impairment after age 70.

The study encompassed 7,005 individuals, with 902 receiving a clinical dementia diagnosis and 2,407 identified with mild cognitive impairment. It investigated the relationship between occupational physical activity over the course of middle age and the risk of dementia and mild cognitive impairment in the elderly, with an equal representation of women among the participants.

Results showed that individuals over 70 who had engaged in physically demanding jobs had a 15.5 percent risk of cognitive ailments, while those in less physically demanding positions had only a 9 percent risk.

“Our findings especially highlight the necessity of monitoring individuals with a high cumulative occupational physical activity as they seem to be at a higher risk for dementia,” Skirbekk remarked. He suggests that future studies should evaluate the interplay between occupational physical activity levels, occupational modifications or technological advancements that change activity levels, and other job factors in relation to the risk of dementia and mild cognitive impairment at advanced ages. Such research would deepen our understanding of the link between occupational history and cognitive decline.

Reference: “Trajectories of occupational physical activity and risk of later-life mild cognitive impairment and dementia: the HUNT4 70+ study” by Ekaterina Zotcheva et al., published on 29 August 2023 in The Lancet Regional Health – Europe.
DOI: 10.1016/j.lanepe.2023.100721

Ekaterina Zotcheva of the Norwegian National Centre of Ageing and Health is a co-author.

The study was financed by the National Institutes of Health and the Research Council of Norway.

Frequently Asked Questions (FAQs) about Occupational Cognitive Decline

More about Occupational Cognitive Decline

• The Lancet Regional Health – Europe study
• Columbia Public Health research on PA paradox
• HUNT4 70+ Study details
• NIH support for occupational cognitive decline research
• Research Council of Norway