Plasticity of memory for new learning in very old age: a story of major loss?

Longitudinal survivors of the Berlin Aging Study (N = 96, mean age = 84 years, range 75-101 years) were instructed and trained in a mnemonic skill to examine plasticity of episodic memory performance in very old age. Performance gains after mnemonic instruction were modest, and most individuals were unable to further enhance their performance during 4 sessions of mnemonic practice. Whereas the proportion of variance explained by measures from the broad fluid-ability domain (e.g., perceptual speed) increased with training, the proportion of variance explained by crystallized-ability domain (e.g., word knowledge) and sociobiographical variables decreased. Furthermore, prior 6-year longitudinal changes (loss) in perceptual speed predicted individual differences in plasticity. Results suggest that aging-induced biological factors are a prominent source of individual differences in cognitive plasticity in very old age.