Neuroanatomical correlates of cognitive aging: evidence from structural magnetic resonance imaging

To examine putative brain substrates of cognitive functions differentially affected by age the authors measured the volume of cortical regions and performance on tests of executive functions, working memory, explicit memory, and priming in healthy adults (18-77 years old). The results indicate that shrinkage of the prefrontal cortex mediates age-related increases in perseveration. The volume of visual processing areas predicted performance on nonverbal working memory tasks. Contrary to the hypotheses, in the examined age range, the volume of limbic structures was unrelated to any of the cognitive functions; verbal working memory, verbal explicit memory, and verbal priming were independent of cortical volumes. Nevertheless, among the participants aged above 60, reduction in the volume of limbic structures predicted declines in explicit memory. Chronological age adversely influenced all cognitive indices, although its effects on priming were only indirect, mediated by declines in verbal working memory.