Experts have long warned about the potential dangers of a sedentary lifestyle. Many studies suggest that being physically inactive increases the risk of health issues.
However, the connection between being physically active and maintaining cognitive health has been less clear. Now, a new study from the University of Cambridge in the United Kingdom further emphasizes this uncertainty.
The research has found that people with desk jobs are far less likely to experience cognitive decline than those with physically active roles.
“The often-used mantra ‘what is good for the heart, is good for the brain’ makes complete sense, but the evidence on what we need to do as individuals can be confusing,” says lead author Shabina Hayat.
“With our large cohort of volunteers, we were able to explore the relationship between different types of physical activity in a variety of settings,” she adds.
The research appears in the International Journal of Epidemiology.
The study is based on data from the Epic-Norfolk Cohort, a long-term project involving some 30,000 participants aged 40 to 79. It aims to investigate links between daily activities, diet, and cancer.
Across an average of 12 years, investigators assessed participants’ cognition, including attention, memory, and visual processing speed. Researchers also administered a reading-ability test that roughly captured each individual’s IQ.
Among the data collected was information regarding levels of physical activity during work hours and leisure time. Measurements of an individual’s physical activity in the Cambridge study combined the two.
A total of 8,585 individuals from the Epic-Norfolk study served as the cohort for the new Cambridge study.
The study reports that those with desk jobs — which are typically sedentary roles — have a lower risk of cognitive decline. Moreover, people with lifelong desk-based careers were most likely to be among the study’s top 10% of cognitive performers.
Conversely, people whose jobs involve manual work have nearly three times the risk of developing poor cognition.
Hayat proposes that it may be the job itself that provides the benefit. “Because desk jobs tend to be more mentally challenging than manual occupations, they may offer protection against cognitive decline,” Hayat says.
“Our analysis shows that the relationship between physical activity and cognitive [function] is not straightforward,” Hayat admits.
“While regular physical activity has considerable benefits for protection against many chronic diseases, other factors may influence future poor cognition.”
The researchers also looked at the potential impact of education level on cognition, but found little evidence that it was relevant. Hayat says that “people who have less active jobs — typically office-based, desk jobs — performed better at cognitive tests regardless of their education.”
The team also looked into the relationship between leisure physical activity and cognition. They were unable to draw any strong associations, at least partially, because such activities were “confounded by education, social class, and occupation.”
Confusingly, the data also suggest that leisure physical activity may offer some cognitive protection, though this seems to contradict the study’s main finding that work-related physical activity does not.
The data “reveals a differential in the association between cognition and inactivity during work and leisure,” says the study. Though exactly what that is remains unclear, particularly in light of the lower leisure-time activity levels reported by those with physical jobs.
People who were physically active during work were less likely to be similarly active during their time off.
The study concludes with an argument for additional research:
“Further studies are needed, in particular, on inequalities across socio-economic groups and the impact of lower education, poor-quality work (shortage of beneficial physical and mental stimulation), particularly for manual labor, and the lack of opportunity and space to be physically active for leisure. All these are key drivers that provide fewer opportunities to build cognitive reserve to protect for cognitive impairment and dementia in later life.”
