The hazards of cognitive aging.

After a review of findings from the Seattle Longitudinal Study of adult cognitive development, this paper discusses the application of event history analysis, a technique pioneered by sociologists, to data involving changes of states in individual behavior related to human aging. The dependent variable of interest for psychologists and other developmentalists should be the age (calendar or functional) at which the event occurs rather than its index in historical time. Using occurrence of significant decline in cognitive abilities as an exemplar, hazard functions are presented that allow the assessment of risk for future decline, as well as the prediction of the calendar age when individuals can expect cognitive decline under alternative assumptions.