For many people, the daily physical and mental activity is found as much within their working lives as within leisure time. However, new research may add nuance to the accepted idea that the “best studied way to prevent or slow the onset of dementia is to stay active, both physically and mentally, every day.“ With a potential link between occupational stress and dementia, providers and patients should also consider the qualities of the physical and mental activity.

Self-directed and Externally-Directed Activity

While clearly an active lifestyle is a critical beneficial factor in deterring cognitive decline, Frontiers in Human Neuroscience recently published a study of 100 participants over age 60 that indicated “physical stress, comprising physical demands and work conditions, was associated with smaller hippocampal volume and poorer memory performance.”1 Individuals who reported feeling physically drained during their careers throughout the workday (whether from office work or manual labor) showed increased risk factors for dementia. 

Exercise increases brain volume by raising levels of chemicals that promote new brain cell formation and new neural connections. But the research suggests self-directed exercise may produce a result which externally-directed (or controlled) physical activity may not. In general, self-directed activity produced healthier outcomes than controlled activity. 

As a New York Times article reporting on this study put it:

 “Context matters. In studies with lab rodents…similar amounts of exercise can lead to contrasting health outcomes, depending on whether the animals run voluntarily on wheels…[or] with researchers manipulating the pace and duration of their exertions [on a treadmill].” 

Understanding Occupational Stress and Dementia

An enriching work environment may protect against age-related cognitive impairment. However, occupational stress, including work that is physically and mentally taxing, may “deplete the brain reserve and accelerate age-related changes through a variety of neural and systemic processes.” 

Prior to this research, only one study linked occupational stress to brain structure. It found that burnout in middle-aged workers was related to decreased volumes of several brain regions, but not the hippocampus.2 The most recent research cited used an assessment of subjective occupational experiences (a 77-item Work Design Questionnaire), MRI scans, and the Virginia Cognitive Aging Project cognitive battery to assess cognitive function over time, and showed the surprise result of physically active individuals with reduced hippocampus volumes. While the study does not show that physically demanding work causes brains to change it does show that “they are related in some way,” according to lead researcher Dr. Agnieszka Z. Burzynska.

Employment as a Cognitive Health Risk Factor

Physicians know that an appointment isn’t a rapid discussion of symptoms. Details about patients’ lives — what they do for work, how they spend their time, whether they smoke or drink, and more — also provide important context and insight. 

Clinicians already know health risks of sedentary jobs, which put patients at increased risk for weight gain and/or low cardiovascular activity. Based on the Burzynska study, providers ought to consider work-specific stress a potential indicator for cognitive impairment risks, as well.

To determine if a work environment is a cognitive health risk factor, providers should go beyond asking what patients do. Question whether their work conditions and physical stresses leave patients feeling drained at the end of the day. If so, an early regimen of cognitive assessment may ensure an accurate longitudinal analysis of brain health. 

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References:

Burzynska AZ, Ganster DC, Fanning J, Salerno EA, Gothe NP, Voss MW, McAuley E and Kramer AF (2020) Occupational Physical Stress Is Negatively Associated With Hippocampal Volume and Memory in Older Adults. Front. Hum. Neurosci. 14:266. doi: 10.3389/fnhum.2020.00266

Blix, E., Perski, A., Berglund, H., and Savic, I. (2013). Long-term occupational stress is associated with regional reductions in brain tissue volumes. PLoS One 8:e64065. doi: 10.1371/journal.pone.0064065