If you suspect your stressful job is killing you, a new study says you may be right — especially if you're a woman.
After analyzing data on nearly 140,000 workers from three continents, researchers found that those with "high-strain" jobs were 22% more likely than their peers to suffer a stroke. The risk was particularly acute for women, who were 33% more likely to have a stroke if their jobs fell into this most stressful category.
The findings, published Wednesday in the journal Neurology, combine results from six previous studies that examined the relationship between work stress and stroke risk. Each of the studies included a baseline assessment of people's job strain, then tracked their health for 3.4 years to 16.7 years. The workers ranged in age from 18 to 75.
Many of the workers had demanding jobs, but not all of those jobs were considered stressful. The researchers, from China, used a well-established method to categorize jobs into four categories.
To do this, they considered whether a job involved a high degree of "psychological job demand." That's a measure of the mental load required to carry out tasks, the amount of management and coordination required to finish those tasks and the time pressure imposed by deadlines, among other things. The researchers also considered how much latitude workers had in deciding how to carry out their assignments, a factor known as "job control."
Dr. Jennifer Majersik, a stroke neurologist at the University of Utah, described the four categories in an editorial that accompanied the study. Jobs on the low end of the spectrum for both psychological demand and control are considered "passive," such as manual labor gigs. These stand in contrast to "active" jobs that combine high psychological demand and high control (think doctors and engineers).
In between are "low-strain" professions that feature low psychological demand and high control, such as scientists and architects, Majersik wrote. Finally, there are "high-strain" jobs that pair high psychological demand with a lack of control; waitresses, nursing aides and other service-industry occupations typify this category, she wrote.
The risk of stroke was lowest for people with low-strain jobs, the Chinese researchers found. They were followed by people with passive and active jobs, though the differences were so small that they could have been due to chance. The only difference big enough to be considered statistically significant was for people with high-strain jobs; the stroke risk for these unlucky workers was 22% higher than for people in the low-strain category.
Unfortunately, high-strain jobs were not that rare. In six studies included in the analysis, the percentage of jobs classified as "high strain" ranged from 11.1% to 26.6%. One of those six studies involved U.S. workers, and 20.4% of them had high-strain jobs.
When the researchers analyzed women separately from men, they found that gender mattered. For women (who made up 91% of the study sample), having a high-strain job was associated with a 33% increased risk of stroke compared with having a low-strain job. If high-strain jobs did not exist, strokes among working women would fall by 6.5%, the study authors calculated.
The data suggest that high-strain jobs raise stroke risk for men as well, but with only 12,323 men in the study, their results weren't statistically significant.
The researchers also ran their numbers separately for different kinds of stroke. They found that having a high-strain job raised the risk of an ischemic stroke — the type that occurs when a clot cuts off blood supply to the brain — by 58%. (Ischemic strokes account for about 87% of all strokes, according to the American Stroke Assn.) However, the increased risk of a hemorrhagic stroke — the kind that happens when a blood vessel ruptures and causes blood to accumulate in the brain — wasn't statistically significant.
There are plenty of ways a high-strain job could make someone more vulnerable to a stroke, the researchers wrote. Stressed-out workers might cope by smoking, eating fast food, skipping out on the gym or making other choices that increase their stroke risk. Long-term stress also messes with blood pressure, which can destabilize plaques in the arteries, and can weaken the immune system by boosting the body's production of the hormone cortisol.
Previous studies also have linked high-stress jobs to an increased risk of cardiovascular disease, which also can be a risk factor for stroke.
Whatever the biological explanation, the study highlights the need to find ways to turn high-strain jobs into low-strain jobs. Employers could redesign jobs to give workers more control over their tasks, and workers could use cognitive behavioral therapy, relaxation therapy or other psychological methods, the study authors wrote.
"It is of vital importance for individuals with high-strain occupations to address lifestyle issues," they wrote. "Successful interventions could have a major public health impact."