September 10, 2021
Numerous studies have found that a mentally challenging job may help to lower the risk of Alzheimer’s disease and other forms of dementia. A new analysis suggests why: mental stimulation may be linked to proteins the blood that allow brain cells to forge new connections throughout adulthood.
A rich network of brain connections is thought to be an important component of what is called cognitive reserve, which can help the brain to compensate against some of the deterioration of the brain that aging can bring, before it develops into full blown dementia. Indeed, if some brain cells are lost while aging, enough healthy cells and connections remain to keep thinking and memory skills intact.
Studies have shown that attaining many years of formal education may help to ward off dementia in old age, possibly by building up higher levels of cognitive reserve. Lifelong learning, through an intellectually stimulating job, may likewise help to build up cognitive reserve. Just as muscles need to be stressed and challenged to grow, so must the brain. “Use it or lose it,” the saying goes.
For this very large study, researchers analyzed work and medical records from 107,896 men and women living in the United States, Britain and Europe. The researchers had detailed information on how mentally challenging their work was. A cognitively stimulating “active” job included one that required completing demanding tasks, but where people had a fair amount of control and autonomy in getting the job done. Non-stimulating “passive” jobs were ones with low demands and lack of job control.
Study participants were tracked for an average of 17 years to see if they developed Alzheimer’s disease or other forms of dementia. The researchers found that those who had mentally stimulating jobs were 23 percent less likely to develop Alzheimer’s disease or other forms of dementia than those who did not have intellectually stimulating jobs. The association persisted even after considering factors like age, sex, and medical conditions like diabetes, heart disease and stroke that can increase the risk of dementia.
The researchers also noted that having lots of years of formal education and a mentally stimulating job afforded even more brain protection. Those with lots of schooling and a challenging job were 37 percent less likely to develop dementia than their peers with neither. The combination of high work demands and low control at work, on the other hand, which would create a highly stressful work environment and high levels of job strain, might increase the risk for dementia rather than protect against it, the authors noted.
Further analysis of blood samples in more than 15,000 of the participants suggested one reason why stimulating work may help to gird the brain. The researchers found that those who had high levels of mental enrichment at work tended to have blood composition differences — including lower levels of a handful of blood proteins that might inhibit the formation of connections between brain cells. Lower levels of these proteins are associated with the development of new axons, the long projections that connect one brain cells to another, and synapses, the messenger-rich interfaces between brain cells that allows two brain cells to communicate, thereby potentially helping to increase cognitive reserve and to lower the risk of dementia.
The findings, published in the British medical journal The BMJ, build on earlier studies showing the benefits of work for brain health. A study from 2020 found, for example, that women who had paying jobs as young adults into middle age had slower rates of age-related memory decline than women who did not have paying jobs. Another study, from 2015, found that over many years, professionals whose jobs require such skills as strategizing, speaking, resolving conflicts and managing others may be less likely to suffer from memory and thinking problems than those with less demanding jobs.
While many factors determine who ultimately develops Alzheimer’s disease, these and other studies suggest that having a job that challenges the intellect may help to keep the mind sharp into old age.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Sources: Mika Kivimaki, Jaana Pentti, Keenan A. Walker, et al: “Cognitive stimulation in the workplace, plasma proteins, and risk of dementia: three analyses of population cohort studies.” The BMJ, August 19, 2021. Serhiy Dekhtyar, “Cognitive stimulation at work and dementia” (editorial). BMJ, August 19, 2021.
