Cognitive and sociodemographic risk factors for mortality in the Seattle Longitudinal Study.

Abstract

The relationship between cognitive function and survivorship was examined in a community-dwelling sample. Survival analysis was used to examine how level and change in intellectual functioning, verbal memory, perceptual speed, and psychomotor speed were related to mortality in a sample of 601 individuals who subsequently died (decedents; n = 342 men; n = 259 women; M = 73.81 years of age) and a control group of 609 survivors (n = 296 men; n = 313 women; M = 71.96). The sample of survivors was selected to be of similar age and to have a similar level of education as the decedents. Individuals in the lowest 25th percentile of performance (crystallized abilities, visualization abilities, verbal memory, and perceptual and psychomotor speed) had a significant risk for subsequent mortality compared to individuals in the highest 25th percentile. However, after adjusting for demographic variables and psychomotor speed, only perceptual speed remained a significant risk factor for mortality. Significant 7-year declines (lowest 25th percentile) in measurements of Verbal Meaning, Spatial Ability, Reasoning Ability, and Psychomotor Speed were risk factors for subsequent mortality relative to those who had the least amount of decline. The relationship between mortality and cognitive function tended to be a specific rather than a pervasive phenomenon, even after adjusting for sociodemographic factors and psychomotor speed. Decrease in cognitive performance tended to be a better predictor of subsequent mortality than was the level of cognitive performance.