We’ve been reporting on the importance of physical activity to keep your brain in good shape for many years now. The science is clear that staying physically active is essential to maintaining a sharp, fog-free, focused memory as you get older.
But could there be a situation in which physical activity has negative consequences and could actually harm the brain? The surprising answer is, yes…
Under certain circumstances physical activity can and does hurt your brain, according to researchers. It’s a process that has even been given its own term – the “physical activity paradox”.
A new study delves deeply into this issue and reveals how you can protect yourself….
Columbia University researchers were fascinated by the science to date that showed how leisure time physical activity is undoubtedly good for the brain, but that those working in occupations with high physical demands ended up with worse cognitive outcomes and a higher risk of dementia later in life.
Past Research Shows When Activity Hurts Memory
For instance, in one study, men aged 40 to 59 years old with physically demanding jobs had a whopping 48 percent higher dementia risk at ages 60+ than those working in predominantly sedentary occupations.
Another study found an increased dementia risk of those with high occupational physical demands after a follow-up of 21 years. And a third study found higher work-related physical activity in the decades of the 20s, 40s, and 50s increased the likelihood of Alzheimer’s later in life.
Prior studies examining this issue all have limitations, however. For one thing, they may ask participants to self-report activity, which is prone to error and bias. Or the researchers may assess physical activity at a single point in time, even though people often change jobs and physical requirements with them. Assessments may also take place too close to retirement, even though the disease process can start decades before a diagnosis is made.
To resolve these issues scientists at Columbia University, New York, set about conducting a more robust study which was published in the journal The Lancet in August.
Increased Dementia Risk by 34 Percent
The Columbia scientists used research from one of the world’s largest population-based studies of dementia, the HUNT4 70+ Study of people living in Norway. Their analysis included 7,005 men and women, 902 of which were clinically diagnosed with dementia and 2,407 with mild cognitive impairment. The team assessed trajectories of occupational physical activity between the ages of 33 to 65 and compared these results with the risk of dementia and mild cognitive impairment (MCI) at age 70+.
Data included workers from 305 occupations, and the scientists defined physical activity as requiring considerable use of arms and legs and moving the whole body. The examples given were climbing, lifting, balancing, walking, stooping, and handling of materials. They graded levels of activity on an intensity scale of one to five.
After making statistical adjustments to consider the effects on cognition of education, income, marital status, health, and lifestyle-related factors, the researchers found that, compared to participants with stable, low occupational physical activity throughout the period, those with high physically demanding jobs had an 80 percent greater risk of MCI and a 34 percent higher risk of dementia.
Why would this be?
Physical Work or Something Else?
In their study, common occupations with high physical workloads included salespersons, nursing and care assistants, construction workers, crop farmers and livestock producers.
The researchers suggested the reasons why these occupations could harm the brain are because they “are often characterized by a lack of autonomy, prolonged standing, hard work, rigid working hours, stress, a higher risk of burnout, and sometimes low socioeconomic status and inconvenient working days.”
Other factors that could apply, they suggested, include lack of recuperation from greater physical demands resulting in more ‘wear and tear’ and shorter recovery periods. Lack of cognitive stimulation, hearing loss, and exposure to pollution are additional factors to add to the mix.
This research seems like it’s just scratching the surface on the effects of high-demand physical work on the brain. While the Columbia team examined half a dozen factors, there are many additional factors that negatively impact brain health that were not considered and adjusted for in their study. So, while highly suggestive, more in-depth research is needed to understand the physical activity paradox.
However, one thing’s for sure, as the authors point out: “there is extensive evidence from observational and experimental studies on the benefits of leisure-time physical activity for brain health.”
And I’ll go one step further and point to other research that has revealed the overwhelmingly positive impact an anti-inflammatory diet can have on your cognitive function and how it can help you protect against memory loss as you age. So, whether you’ve been involved in physically demanding jobs or not, changing your diet and lifestyle to protect your brain can help you preserve your cognitive function for years to come.
The Awakening From Alzheimer’s Team
Trajectories of occupational physical activity and risk of later-life mild cognitive impairment and dementia: the HUNT4 70+ study https://www.sciencedirect.com/science/article/pii/S2666776223001400