Survival effects in cognitive function, cognitive style, and sociodemographic variables in the Seattle Longitudinal Study.

Survival effects in cognitive performance were examined in the Seattle Longitudinal Study (SLS) for a sample of 605 individuals who subsequently died (decedents) (n = 343 males; n = 262 females; M = 73.73 years of age) and a control group of 613 survivors (n = 299 males; n = 314 females; M = 71.91 years of age). A sample of survivors of similar age and have a similar level of education as the decedents was selected. Differences in cognitive functioning and cognitive style in level and change over time between decedents and survivors were studied. Decedents had lower levels of crystallized abilities (Verbal Meaning and Numerical Ability), visualization abilities (Spatial Orientation), verbal memory (Delayed Word Recall), perceptual speed (Identical Pictures), and Psychomotor Speed at last measurement. Decedents also had greater declines on Psychomotor Speed and Verbal Meaning at 7 and 14 years before the conclusion of the study. Survival effects were found to be ability-specific, appeared primarily in older adults, were more evident for males, and were observed up to 14 years before last measurement for specific abilities. Age-related changes in fluid ability appeared to be normative, whereas changes in crystallized abilities and perceptual speed may signify impending mortality.