HealthDay News — Individuals with cognitively stimulating jobs have a lower risk for dementia in old age than individuals with nonstimulating jobs, according to a study published online Aug. 18 in The BMJ.

Mika Kivimäki, Ph.D., from University College London, and colleagues conducted a multicohort study in the United Kingdom, Europe, and the United States to examine the association between cognitively stimulating work and subsequent dementia risk. Three associations were examined: cognitive stimulation and dementia risk in 107,896 participants; cognitive stimulation and proteins in a sample of 2,261 participants; and proteins and dementia risk in 13,656 participants.

The researchers found that 1,143 people with dementia were recorded during 1.8 million person-years at risk. Dementia risk was lower for participants with high versus low cognitive stimulation at work (age- and sex-adjusted hazard ratio, 0.77; 95 percent confidence interval, 0.65 to 0.92); this association was robust to additional adjustment (fully adjusted hazard ratio, 0.82; 95 percent confidence interval, 0.68 to 0.98). The risk for dementia was seen during the first 10 years of follow-up and from year 10 and onward (hazard ratios [95 percent confidence intervals], 0.60 [0.37 to 0.95] and 0.79 [0.66 to 0.95], respectively). Higher cognitive stimulation at work was associated with lower levels of proteins that inhibit central nervous system axonogenesis and synaptogenesis: slit homologue 2, carbohydrate sulfotransferase 12, and peptidyl-glycine α-amidating monooxygenase; these proteins were associated with increased dementia risk (fully adjusted hazard ratios per one standard deviation [95 percent confidence intervals], 1.16 [1.05 to 1.28], 1.13 [1.00 to 1.27], and 1.04 [0.97 to 1.13], respectively).

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“A possible mechanism for this association is the finding that cognitive stimulation is associated with lower levels of plasma proteins that might inhibit axonogenesis and synaptogenesis and increase dementia risk in old age,” the authors write.

Two authors disclosed financial ties to the biopharmaceutical industry.

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