People with a history of cognitively stimulating occupations during their 30s, 40s, 50s and 60s had a lower risk of mild cognitive impairment (MCI) and dementia after age 70, according to a new study from the Mailman School of Public Health at the Columbia University, the Columbia Aging Center and the Norwegian Institute of Public Health. The findings highlight the importance of cognitive stimulation during midlife to maintain cognitive function in old age.
This is the first study to fully advance this association with objective assessments rather than subjective assessments. The results were published in Neurology .
"Our study highlights the importance of mentally challenging work tasks for maintaining cognitive functioning in old age," says Vegard Skirbekk, Ph.D., professor of Epidemiology at the Columbia Mailman School of Public Health and the Columbia Center on Aging, who started the project. Author Trine Holt Edwin from Oslo University Hospital: "This study shows the importance of education and cognitive stimulation of working life for cognitive health in old age."
The researchers collected data from the Norwegian administrative register and combined it with occupational attributes of more than 300 jobs from the US Department of Labor, Employment and Training Administration´s Occupational Information Network (O*NET) 17 database. The routine task intensity index (RTI) was calculated as a measure of occupational cognitive demands based on O*NET measures. A lower RTI index indicates more cognitively demanding occupations. This research builds on previous findings showing trajectories of occupational physical activity.
The cluster-based trajectory model identified four clusters of distinct occupational cognitive demands based on the degree of routine tasks in participants´ occupations during their 30s, 40s, 50s, and 60s. The researchers analyzed the link between these trajectory groups and clinically diagnosed mild cognitive impairment and dementia in HUNT4 70+ study participants (2017-19). Additionally, the researchers took into account important risk factors for dementia, such as age, sex, educational level, income, general health, and lifestyle habits, from evaluations conducted in 1984–86 and 1995. –97.
After adjusting for age, sex, and education, the group with low occupational cognitive demands (the high RTI group) had a 37% increased risk of dementia compared to the group with high occupational cognitive demands .
"Education confounded most, but not all, of the association between occupational cognitive demands and MCI and dementia, suggesting that both education and occupational complexity are important for MCI and the risk of dementia," says Edwin.
The findings advance the field in several ways, according to the authors. "First, occupational cognitive demands have often been assessed using subjective, retrospective assessments. Furthermore, our use of occupational history registry data strengthens the existing evidence," says Yaakov Stern, principal investigator of the project at Columbia University. .
"Overall, our study demonstrates that high occupational cognitive demands are related to lower risks of mild cognitive impairment and dementia in old age ," Skirbekk noted, indicating that both education and occupational cognitive demands play a crucial role in reducing the risk of cognitive decline in old age. "However, we recommend commissioning further research to validate these findings and identify the specific occupational cognitive demands that are most advantageous for maintaining cognitive health in old age."
It is important to note that this study identifies associations rather than direct causes of dementia. Furthermore, the study did not distinguish between different cognitive requirements within the same occupational category, nor did it consider the evolution of job responsibilities over the years.
People with a history of cognitively stimulating occupations during their 30s, 40s, 50s, and 60s had a lower risk of mild cognitive impairment and dementia over age 70, highlighting the importance of occupational cognitive stimulation during midlife to maintain cognitive function in old age. Further research is required to identify the specific occupational cognitive demands that are most advantageous for maintaining cognitive function in old age.
Co-authors are Asta Kristine Håberg, Ekaterina Zotcheva, Bernt Bratsberg, Astanand Jugessur, Bo Engdahl, Catherine Bowen, Geir Selbæk, Hans-Peter Kohler, Jennifer R. Harris, Sarah E. Tom, Steinar Krokstad, Teferi Mekonnen and Bjørn Heine. Strand.
