Certain proteins might provide clues to underlying biological mechanisms, say researchers.
People with mentally stimulating jobs have a lower risk of dementia in old age than those with non-stimulating jobs, finds a study published by The BMJ today (August 18, 2021).
One possible explanation is that mental stimulation is linked to lower levels of certain proteins that may prevent brain cells forming new connections (processes called axonogenesis and synaptogenesis).
Cognitive stimulation is assumed to prevent or postpone the onset of dementia. But trial results have varied and 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 benefits.
So an international team of researchers set out to examine the association between cognitively stimulating work and subsequent risk of dementia and to identify protein pathways for this association.
Their findings 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.
Three associations were examined: cognitive stimulation and dementia risk in 107,896 participants (42% men; average age 45 years) from seven studies from the IPD-Work consortium, a collaborative research project of 13 European cohort studies; cognitive stimulation and proteins in a random sample of 2,261 participants from one study; and proteins and dementia risk in 13,656 participants from two studies.
Cognitive stimulation at work was measured at the start of the study and participants were tracked for an average of 17 years to see if they developed dementia.
Cognitively stimulating “active” jobs include demanding tasks and high job decision latitude (also known as job control), while non-stimulating “passive” jobs are those with low demands and lack of job control.
After adjusting for potentially influential factors, including age, sex, educational attainment, and lifestyle, risk of dementia was found to be lower for participants with high compared with low cognitive stimulation at work (incidence 4.8 per 10,000 person-years in the high stimulation group and 7.3 in the low stimulation group).
This finding remained after further adjustments for a range of established dementia risk factors in childhood and adulthood, cardiometabolic diseases (diabetes, coronary heart disease, and stroke), and the competing risk of death.
The association did not differ between men and women or those younger and older than 60, but there was an indication that the association was stronger for