Cognitive Deficit and the Aging Brain: A Behavioral Analysis

Abstract

Cross-sectional comparisons were performed between young and old subject groups matched for socioeconomic status (SES) and vocabulary score on Raven's Colored Progressive Matrices, an incomplete figure recognition test (IFR), and a measure of auditory letter span (ALS). The elderly group's performance was relatively inferior on all three measures, but least so on the ALS, for which they were able to use their overlearned knowledge of English spelling patterns. Deficit on the unfamiliar “right-hemispheric” IFR was fully accounted for by deficit on Matrices. This loss on a test of cerebrally localizable process (IFR) and on a non-localizable test presumably indicative of diffuse neuronal depletion (Matrices) were comparable in extent, suggesting that basically homogeneous cerebral atrophy in aging equally affects focally and diffusely organized cerebral processes. Where previously acquired “structure” can be invoked (ALS), test performance is relatively preserved.