A new study has found a clear link between consistently engaging in jobs with moderate to high levels of physical activity and a heightened risk of cognitive decline.
These findings emphasize the importance of implementing preventive measures for individuals employed in physically demanding occupations to stave off cognitive impairment.
The research was recently published in The Lancet Regional Health – Europe.
The Physical Activity Paradox
The study delves into what is known as the “physical activity (PA) paradox.” This paradox illustrates the stark contrast in the impact of leisure time physical activity and work-related physical activity on cognitive outcomes. Dr. Vegard Skirbekk, a professor of Population and Family Health at Columbia Public Health, emphasizes the critical importance of comprehending the relationship between workplace physical activity levels and cognitive impairment.
“It is critically important to understand how workplace physical activity levels relate to cognitive impairment and dementia,” notes Dr. Skirbekk. “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
Previous studies on occupational physical activity and dementia have had their limitations. They often assessed occupation at a single time point in an individual’s career, typically close to retirement, and mainly relied on self-reported data.
The study by Dr. Skirbekk and his team takes a different approach by incorporating a life-course perspective into the research on occupational physical activity and cognitive impairment.
“Whereas previous studies have 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,” explains Dr. Skirbekk.
The preclinical period of dementia can begin up to two decades before symptom onset. Hence, a life-course approach that considers various occupations throughout one’s working life provides a more accurate understanding of the intricate relationships between occupational characteristics and cognitive impairment.
The research, conducted using one of the world’s largest population-based studies of dementia, the HUNT4 70+ Study, assesses the association of occupational physical activity at ages 33–65 with the risk of dementia and mild cognitive impairment at ages 70+.
The analysis included 7005 participants, out of which 902 were clinically diagnosed with dementia, and 2407 were diagnosed with mild cognitive impairment.
Dr. Skirbekk and his colleagues studied the association of trajectories of occupational physical activity at ages 33–65 with the risk of dementia and mild cognitive impairment at ages 70+. Among the participants, half were women.
The results of the study reveal that the risks of 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 their 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,” Dr. Skirbekk emphasizes. “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.”
The implications of this study are profound. It calls for urgent attention to the well-being of individuals employed in physically demanding jobs, as they face an elevated risk of cognitive decline.
Employers, policymakers, and healthcare professionals need to take heed of these findings and consider measures to reduce the cognitive risks associated with physically demanding work.
Published 29 August 2023, The Lancet Regional Health – Europe; “Trajectories of occupational physical activity and risk of later-life mild cognitive impairment and dementia: the HUNT4 70+ study”