The Physical Activity Paradox: New Study Links Physical Labor to Cognitive Impairment

A new study from 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 found a connection between consistently engaging in jobs with moderate to high levels of physical activity and a heightened risk of cognitive decline.

These findings underscore the necessity for creating preventive measures for those employed in physically demanding occupations to prevent cognitive impairment. The findings were recently published in The LancetFounded in 1823 by Thomas Wakley, The Lancet is a weekly peer-reviewed general medical journal. It is one of the world's oldest, most prestigious, and best known general medical journals. The journal publishes original research articles, review articles ("seminars" and "reviews"), editorials, book reviews, correspondence, as well as news features and case reports. The Lancet has editorial offices in London, New York, and Beijing. ” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>The Lancet Regional Health – Europe.

The Physical Activity Paradox

“It is critically important to understand how workplace physical activity levels relate to cognitive impairment and dementia,” observed Vegard Skirbekk, PhD, professor of Population and Family Health at Columbia Public Health. “Our work also highlights what is called the physical activity (PA) paradox – the association of leisure time physical activity with better cognitive outcomes, and how work-related physical activity can lead to worse cognitive outcomes.”

Methodology and Prior Research

Until now prior studies on occupational physical activity and dementia had been limited. Earlier studies have typically assessed occupation at a single time point in the individual’s career — often close to retirement — and have mainly been self-reported.

“Our findings extend those from previous studies by incorporating a life-course perspective into research on occupational physical activity and cognitive impairment,” said Skirbekk. “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 the risk of cognitive impairment in later adulthood.”

Skirbekk observes that the preclinical period of dementia may start up to two decades prior to symptom onset, therefore, a life-course approach where different occupations during the working life course are taken into account could provide more accurate information on the complex relationships between occupational characteristics and cognitive impairment.

Study Findings

Using one of the world’s largest population-based studies of dementia, the HUNT4 70+ Study, researchers assessed the association of occupational physical activity at ages 33–65 with the risk of dementia and mild cognitive impairment at ages 70+.

Included in the analysis were 7005 participants, 902 whom were clinically diagnosed with dementia and 2407 diagnosed with mild cognitive impairment. Skirbekk and colleagues assessed the association of trajectories of occupational physical activity at ages 33–65 with risk of dementia and mild cognitive impairment at ages 70+. Of the 7005 participants, half were women.

Risks for dementia and mild cognitive impairment among the 70-year-old and overpopulation were 15.5 percent among those with physically demanding work in the latter part of the working life, but only 9 percent among those with jobs that had low physical demands.

“Our results particularly underscore the need to follow up on individuals with high lifetime occupational, physical activity as they appear to have a greater risk of developing dementia,” noted Skirbekk. “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.”

Reference: “Trajectories of occupational physical activity and risk of later-life mild cognitive impairment and dementia: the HUNT4 70+ study” by Ekaterina Zotcheva, Bernt Bratsberg, Bjørn Heine Strand, Astanand Jugessur, Bo Lars Engdahl, Catherine Bowen, Geir Selbæk, Hans-Peter Kohler, Jennifer R. Harris, Jordan Weiss, Sarah E. Tom, Steinar Krokstad, Teferi Mekonnen, Trine Holt Edwin, Yaakov Stern, Asta Kristine Håberg and Vegard Skirbekk, 29 August 2023, The Lancet Regional Health – Europe.
DOI: 10.1016/j.lanepe.2023.100721

Co-author is Ekaterina Zotcheva, Norwegian National Centre of Ageing and Health.

This work was supported by the National Institutes of HealthThe National Institutes of Health (NIH) is the primary agency of the United States government responsible for biomedical and public health research. Founded in 1887, it is a part of the U.S. Department of Health and Human Services. The NIH conducts its own scientific research through its Intramural Research Program (IRP) and provides major biomedical research funding to non-NIH research facilities through its Extramural Research Program. With 27 different institutes and centers under its umbrella, the NIH covers a broad spectrum of health-related research, including specific diseases, population health, clinical research, and fundamental biological processes. Its mission is to seek fundamental knowledge about the nature and behavior of living systems and the application of that knowledge to enhance health, lengthen life, and reduce illness and disability.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>National Institutes of Health and the Research Council of Norway.