Today’s older adults are cognitively fitter than older adults were 20 years ago, but when and how they decline is no different than in the past
Psychological Science, 34:1, 22–34 (2023)
History-graded increases in older adults’ levels of cognitive performance are well documented, but little is known about historical shifts in within-person change: cognitive decline and onset of decline. We combined harmonized perceptual-motor speed data from independent samples recruited in 1990 and 2010 to age-match 2,008 longitudinal observations (Mage.observations=78 years, 50% women) from n=228 participants in the Berlin Aging Study (BASE) and n=583 participants in Berlin Aging Study II (BASE-II). We used nonlinear growth models that orthogonalize within- and between-person age effects and control for retest effects. At age 78, the later-born BASE-II cohort substantially outperformed the earlier-born BASE cohort (d = 1.20, 25 years of age differences). Age trajectories however were parallel, with no evidence of cohort differences in amount/rate of decline or onset of decline. Cognitive functioning has shifted to higher levels, but cognitive decline in old age appears to proceed similarly to how it did two decades ago.