Cognitively Stimulating Jobs May Protect Against Dementia

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 by researchers at Columbia University Mailman School of Public Health, The Robert N. Butler Columbia Aging Center, and the Norwegian Institute of Public Health. The findings highlight the importance of cognitive stimulation during midlife for maintaining cognitive function in old age.

The study is the first to fully advance the association between cognitively stimulating occupations and reduced risk for MCI and dementia with objective assessments rather than subjective evaluations. The results are published in Neurology.

“Our study highlights the importance of mentally challenging job tasks to maintain cognitive functioning in later life,” says Vegard Skirbekk, PhD, professor in the Heilbrunn Department of Population and Family Health and the Columbia Aging Center, who initiated the project. First author Trine Holt Edwin from Oslo University Hospital, adds, “This study shows the importance of education and cognitively stimulating work life for cognitive health in older age.”

The researchers collected data from the Norwegian administrative registry and coupled it with occupational attributes of more than 300 jobs from the Occupational Information Network (O*NET) database17 of the U.S. Department of Labor, Employment & Training Administration. Routine task intensity (RTI) index was computed as a measure of occupational cognitive demands based on measures from O*NET. A lower RTI index indicates more cognitively demanding occupations. This research builds upon previous findings showing trajectories of occupational physical activity.

Group-based trajectory modeling identified four groups of distinct occupational cognitive demands according to 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 MCI and dementia in participants in the HUNT4 70+ Study (2017-19). Additionally, the researchers accounted for important dementia risk factors such as age, gender, educational level, income, overall health, and lifestyle habits from assessments made in 1984-86 and 1995-97. 

Within age groupings, the researchers looked at such occupations as primary school teacher, salesperson, nurse and caregiver, office cleaner, civil engineer, and mechanic, among others.

After adjusting for age, sex, and education, the group with low occupational cognitive demands (the high RTI group) had a 37 percent higher 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 matter for MCI and dementia risk,” says Edwin.

The findings advance the field in several ways, according to the authors. "First, occupational cognitive demands have often been assessed via retrospective, subjective evaluations. Additionally, our utilization of registry data on occupational histories strengthens the existing evidence,” says Yaakov Stern, PhD, in the Department of Neurology at Columbia University Vagelos College of Physicians and Surgeons and principal investigator of the project at Columbia.

“Overall, our study demonstrates that high occupational cognitive demands are related to lower risks of MCI and dementia in later life,” noted Skirbekk, indicating that both education and occupational cognitive demands play a crucial role in lowering the risk of later-life cognitive impairment. “However, we recommend the commissioning of further research to validate these findings to pinpoint 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 causation of dementia. Moreover, 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. 

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.

The study was supported by a collaboration of the HUNT Research Centre (Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology (NTNU)), Trøndelag County Council, Central Norway Regional Health Authority, the Norwegian Institute of Public Health, and the Cognitive Neuroscience Division, Department of Neurology, Columbia University Vagelos College of Physicians and Surgeons