(HealthDay News) — Individuals with a history of cognitively stimulating occupations from ages 30 to 65 years have lower risk for mild cognitive impairment (MCI) and dementia in later life, according to a study published online April 17 in Neurology.

Trine H. Edwin, MD, PhD, from Oslo University Hospital in Norway, and colleagues examined the association between registry-based trajectories of occupational cognitive demands from ages 30 to 65 years and clinically diagnosed MCI and dementia at age 70 years and older. Occupational cognitive demands were measured by routine task intensity (RTI), with lower RTI indicating a more cognitively demanding occupation. The relative risk ratios (RRRs) of MCI and dementia were estimated after adjustment for multiple confounding variables.

The researchers identified four RTI trajectory groups based on longitudinal RTI scores for 305 unique occupations: low, intermediate-low, intermediate-high and high RTI (20.4, 22.5, 37.1 and 19.9%, respectively). After adjusting for age, sex and education, participants in the high versus the low RTI group had a higher risk for MCI and dementia (RRRs [95% confidence intervals], 1.74 [1.41 to 2.14] and 1.37 [1.01 to 1.86], respectively). The point estimates were not appreciably changed in a sensitivity analysis controlling for income and baseline health-related factors (RRRs [95% confidence intervals], 1.66 [1.35 to 2.06] and 1.31 [0.96 to 1.78], respectively).

“These results indicate that both education and occupational cognitive demands play a crucial role in lowering the risk of later-life cognitive impairment, consistent with the cognitive reserve hypothesis,” the authors write.

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