LONDON — People with mentally stimulating jobs are less likely to suffer from cognitive decline and develop dementia as they grow old, a new study finds.
An international team says one possible reason is that mental stimulation appears to have a connection to lower levels of certain proteins in the brain. These substances can prevent brain cells from forming new connections.
Scientists have suspected that cognitive stimulation prevents or postpones the onset of dementia. However, trial results have varied and the most recent long term studies have suggested that leisure time cognitive activity does not reduce risk of dementia.
Exposure to cognitive stimulation at work typically lasts considerably longer than cognitively stimulating hobbies, yet work-based studies have also failed to produce compelling evidence of these benefits. The team, led by University College London researchers, set out to examine the association between cognitively stimulating work and subsequent risk of dementia.
Their findings, published by The BMJ, are based on studies from the United Kingdom, Europe, and the United States looking at links between work-related factors and chronic diseases, disability, and mortality.
More control over your work benefits the brain
Study authors looked at three specific associations: cognitive stimulation and dementia risk in more than 107,800 participants with an average age of 45; cognitive stimulation and proteins in a random sample of 2,261 participants; and proteins and dementia risk in 13,656 participants.
Researchers measured cognitive stimulation at work at the start of the study and tracked participants for an average of 17 years to see if they developed dementia. Cognitively stimulating “active” jobs include demanding tasks and high job decision latitude (or job control). Meanwhile, non-stimulating “passive” jobs are those with low demands and lack of job control.
After adjusting for potentially influential factors, including age, sex, education, and lifestyle habits, results show the risk of dementia was lower for participants with highly stimulating jobs compared with less stimulating work.
‘Active’ jobs benefit workers of all ages
This findings remained constant after further adjustments for a range of dementia risk factors in childhood and adulthood, including cardiometabolic diseases like diabetes, coronary heart disease, and stroke.
Study lead author Professor Mika Kivimäki says the link did not differ between men and women or those younger and older than 60. However, there is an indication that the association is stronger for Alzheimer’s disease than other forms of dementia. Prof. Kivimäki adds that cognitive stimulation displays a link to lower levels of three proteins tied to dementia onset.
“The findings that cognitive stimulation is associated with lower levels of plasma proteins that potentially inhibit axonogenesis and synaptogenesis and increase the risk of dementia might provide clues to underlying biological mechanisms,” Kivimäki and the team write in a media release.
Researchers note their findings are only observational, so they can’t establish a cause for this link. The team could not rule out the possibility that some of the observed dementia links may be due to other unmeasured factors.
South West News Service writer Stephen Beech contributed to this report.