Mentally Stimulating Activities at Work During Midlife and Dementia Risk After Age 75: Follow-Up Study From the Kungsholmen Project

• Published in: The American journal of geriatric psychiatry 2009-03, Vol.17 (3), p.227-236
• Main Authors: Karp, Anita, Ph.D, Andel, Ross, Ph.D, Parker, Marti G., Ph.D, Wang, Hui-Xin, Ph.D, Winblad, Bengt, M.D., Ph.D, Fratiglioni, Laura, M.D., Ph.D
• Format: Article
• Language: English
• Subjects: Age Factors; Aged; Aged, 80 and over; Alzheimer disease; Cohort Studies; Confidence Intervals; dementia; Dementia - diagnosis; Dementia - epidemiology; education; Educational Status; elderly; Follow-Up Studies; Humans; Incidence; Internal Medicine; Logistic Models; Longitudinal Studies; Male; occupation; Occupations - classification; Occupations - statistics & numerical data; Odds Ratio; population-based study; Proportional Hazards Models; Risk Factors; Sex Factors; Surveys and Questionnaires; Sweden - epidemiology
• ISSN: 1064-7481; 1545-7214
• DOI: 10.1097/JGP.0b013e318190b691

Objectives Previous research has suggested that mental stimulation in different life periods may protect against dementia or delay disease onset. This study aimed to explore the association between work complexity factors at midlife and dementia risk in late life under the hypothesis that high work complexity may modulate the increased dementia risk due to low education. Design Population-based follow-up study. Setting Urban. Participants A cohort of 931 nondemented subjects, aged 75+ years from the Kungsholmen Project, Stockholm, examined twice over 6 years. Measurements Incident dementia cases were identified using Diagnostic and Statistical Manual of Mental Disorders, 3rd-Edition Revised criteria. Primary occupations were assigned into categories according to the Nordic Occupational Classification and matched to the 1970 U.S. Census to score the level of work complexity with data, people, and things by using a preformed matrix. Results Lower dementia risk was associated with complexity of work with both data (age and gender adjusted relative risk [aRR]: 0.85, 95% confidence interval [CI]: 0.75–0.95) and with people (aRR: 0.88, 95% CI: 0.80–0.97). Adjusting for education led to similar results, although no longer statistically significant. Further, the highest degrees of complexity of work with data that involves analyzing, coordinating, and synthesizing data were associated with lower dementia risk even among lower educated subjects (relative risk: 0.52, 95% CI: 0.29–0.95). No gender differences were detected. Conclusions This study suggests that work complexity with data and people is related to lower risk of dementia and that the highest levels of work complexity may modulate the higher dementia risk due to low education.