NEW YORK — Exercise is often recommended as a near-universal panacea these days for afflictions of both the mind and body. Want to get in better shape? Hit the gym! Feeling down lately? Breaking a sweat usually helps. Plenty of people shell out big bucks every month for gym memberships to maintain a certain amount of regular movement, but noteworthy new research suggests daily physical activity isn’t always a positive. Scientists report that working a job requiring medium or high levels of occupational physical activity was linked to an increased risk of cognitive impairment.
Researchers from the Norwegian National Centre of Aging and Health, Columbia University’s Mailman School of Public Health, and the Butler Columbia Aging Center collaborated on the study. The work highlights the urgent need to develop new strategies for individuals in physically demanding occupations to help prevent cognitive impairment.
“It is critically important to understand how workplace physical activity levels relate to cognitive impairment and dementia,” observes Vegard Skirbekk, PhD, professor of Population and Family Health at Columbia Public Health, in a media release. “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.”
What did previous studies on dementia and physical activity at work report?
Up until now, earlier relevant studies focusing on occupational physical activity and dementia had been quite limited. Such projects typically analyzed occupations at a single point in time during a person’s career, in the majority of cases close to retirement age, and with data being collected in a self-reported manner.
“Our findings extend those from previous studies by incorporating a life-course perspective into research on occupational physical activity and cognitive impairment,” Prof. Skirbekk adds. “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 risk of cognitive impairment in later adulthood.”
Study authors explain that the early, preclinical period of dementia may start up to two decades earlier than the appearance of symptoms. Thus, they theorized that accounting for and studying different occupations during working life may help provide more information on the complex and nuanced relationships connecting one’s job or career and cognitive health.
By the numbers
Via one of the biggest ever population-based studies of dementia, the research team assessed the association between occupational physical activity at ages 33-65 years old to subsequent dementia and cognitive impairment risk at ages 70+. A total of 7,005 people were included; 902 were clinically diagnosed with dementia, while 2,407 had been diagnosed with mild cognitive impairment.
Researchers analyzed the connection between occupational physical activity trajectories in adult life (ages 33-65) and dementia/cognitive impairment risk in old age (70+). Half of the included subjects were female.
The risk of developing dementia and mild cognitive impairment among subjects aged 70 or older came in at 15.5 percent for those with a physically demanding job during the latter part of their working life. Yet, the same risk was just nine percent among others 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,” Prof. Skirbekk concludes. “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 study is published in The Lancet Regional Health – Europe.