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

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 case's 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). Acytisting 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% CT 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. (Am J Geriatr Psychiatry 2009; 17:227-236)