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Many non-genetic factors affect our cognitive health and our risk of developing dementia later in our lives, from childhood education to healthy sleep, to lifestyle choices like diet and exercise. Now, researchers are finding that our work is a factor too.
For women, a new study shows that never having a job outside the home could double the risk of developing cognitive impairment by age 70. Meanwhile, men with jobs that involve physical labor like construction, researchers observed, are almost one and a half times more likely to develop dementia than those with less physical work.
Working women — both mothers and not — saw lower rates of cognitive decline compared to women who had never had a job outside the home.
According to a new study published in Neurology, women who held jobs for significant portions of their younger years experienced slower memory decline as they aged than women who had not joined the labor force.
“While there’s no debate that managing a home and a family can be a complex and full-time job, our study suggests that engaging in paid work may offer some protection when it comes to memory loss — possibly due to cognitive stimulation, social engagement, or financial security,” Elizabeth Rose Mayeda of the UCLA Fielding School of Public Health in Los Angeles said in a news statement. “We found the timing of labor force participation did not appear to matter.”
Mayeda and her fellow researchers followed 6,189 women with a mean baseline age of 57 for an average of 12.3 years, and assessed their memory performance once every two years. Participants were placed into five groups based on their work-family profile from ages 16 to 50: working married mothers; working single mothers; working non-mothers; non-working married mothers; and non-working single mothers, accounting for factors like race and ethnicity, childhood socioeconomic status and education.
The researchers found that the average memory score decline was similar for non-working married and single mothers. Between ages 60 and 70, memory score declined more notably among women who had never worked, compared with women who had. Non-working mothers were twice as likely to develop memory impairment at age 70 as working married mothers.
Michelle Mielke of the Mayo Clinic and Bryan James of Rush University in Chicago wrote in an op-ed accompanying the study that the research is particularly relevant for women because of how gender norms of work, parenthood, and marriage have evolved in the past century, and how many more women are now in the labor force.
“Of studies in the dementia field that have incorporated sex and gender, the vast majority focus on sex differences or sex-specific factors including pregnancy, the menopausal transition and use of hormone therapy, genetics, or differences in biomarker profiles,” they wrote. The factor of participation in the workforce has not been closely examined.
“Though not a limitation to the internal validity of this study, it should be noted that this association can only be generalized to American women,” Mielke and James wrote. “This is important, considering societal and historical differences in women’s workforce participation across countries, along with some evidence that disparities in dementia risk between men and women are different in other contexts.”
Nearly two-thirds of those living with Alzheimer’s in the U.S. are women, they noted. The authors added: “Policies that help women with children participate in the workforce may be an effective strategy to prevent memory decline in women.”
Men with jobs that involved physical labor had as much as one-and-a-half times greater dementia risk than those with sedentary jobs.
Exercise — sports, running, and other cardiovascular fitness activities — can reduce inflammation and promote cardiovascular health including blood flow to the brain, which in turn has been shown to benefit cognitive health and prevent or delay the onset of Alzheimer’s and related dementias. But not all physical activity is beneficial.
Research led by scientists at the University of Copenhagen in Denmark has found that sustained, repetitive physical labor can have the opposite effect.
A recent study published in the Scandinavian Journal of Medicine & Science in Sports shows that demanding work involving continuous exertion, heavy lifting, repetitive movements, static postures and long periods of time on one’s feet — such as work in construction — may have the opposite effect of recreational exercise, and could increase the likelihood of developing dementia.
Adjusting for factors like age, socioeconomic status, marital status, mental health, lifestyle choices like smoking and drinking, and health factors like body mass index, the researchers determined that participants who reported that they engaged in high levels of physical labor had nearly 1.5 times the rate of dementia than people who reported less physical kinds of work.
According to Danish researcher Kirsten Nabe-Nielsen who led the study, agencies such as the World Health Organization provide advice on dementia prevention that includes engaging in physical activity, and this research presents convincing evidence that such recommendations need to come with more nuance: “Our study suggests that it must be a ‘good’ form of physical activity, which hard physical work is not,” she said in a news statement. “Guides from the health authorities should therefore differentiate between physical activity in your spare time and physical activity at work, as there is reason to believe that the two forms of physical activity have opposite effects.”