Longitudinal episodic memory trajectories in older adults with normal cognition

Objective To determine the longitudinal trajectories and normative standards of episodic memory in older adults.Methods Participants were drawn from the cognitively normal(CN) subgroup of the population-based HELIAD cohort, a fairly representative cohort of the older Greek population. Verbal and non-verbal memory were assessed using the Greek Verbal Learning Test and Medical College of Georgia-Complex Figure Test. Baseline and longitudinal associations of memory performance with age, sex and formal education were explored with linear regression analysis and generalized estimated equations.Results A total of 1607 predominantly female (60%) individuals (73.82 ± 5.43 years), with a mean educational attainment of 8.17(±4.86) years were CN at baseline. Baseline analysis revealed a continuum of memory decline with aging and lower educational attainment. Women performed better in composite and verbal memory measures, while men performed better in non-verbal memory tasks. A subgroup of 761 participants with available assessments after 3.07(±0.82) years remained CN at follow-up. Composite memory scores yearly diminished by an additional 0.007 of a SD for each additional year of age at baseline. Regarding verbal learning, immediate free verbal recall, delayed free verbal recall and delayed cued verbal recall, an additional yearly decrease of 0.107, 0.043, 0.036 and 0.026 words were respectively recorded at follow-up, for each additional year of age at baseline. Women underwent steeper yearly decreases of 0.227 words in delayed cued verbal recall. No significant longitudinal associations emerged for immediate non-verbal memory, delayed non-verbal memory and immediate cued verbal recall.Conclusions In the present study, aging (but not educational attainment) was consistently associated with steeper verbal memory decline.