Stability, growth, and decline in adult life span development of declarative memory: cross-sectional and longitudinal data from a population-based study.
Five-year changes in episodic and semantic memory were examined in a sample of 829 participants (35-80 years). A cohort-matched sample (N=967) was assessed to control for practice effects. For episodic memory, cross-sectional analyses indicated gradual age-related decrements, whereas the longitudinal data revealed no decrements before age 60, even when practice effects were adjusted for. Longitudinally, semantic memory showed minor increments until age 55, with smaller decrements in old age as compared with episodic memory. Cohort differences in educational attainment appear to account for the discrepancies between cross-sectional and longitudinal data. Collectively, the results show that age trajectories for episodic and semantic memory differ and underscore the need to control for cohort and retest effects in cross-sectional and longitudinal studies, respectively.
Rönnlund
Michael
M
Department of Psychology, Umeå University, Umeå, Sweden. michael.ronnlund@psy.umu.se
Nyberg
Lars
L
Bäckman
Lars
L
Nilsson
Lars-Göran
LG
D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004522:Educational Status; D005500:Follow-Up Studies; D006801:Humans; D008016:Life Change Events; D008569:Memory Disorders / Q000175:diagnosis* / Q000453:epidemiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D011159:Population Surveillance / Q000379:methods*; D012660:Semantics; D012720:Severity of Illness Index