Hippocampal Atrophy Disrupts Transfer Generalization in Nondemented Elderly

Abstract

Specific reductions in hippocampal volume in nondemented elderly individuals with mild cognitive impairment have been shown to correlate with future development of Alzheimer's disease (AD). Hippocampal atrophy (HA) is also correlated with cognitive impairments, leading to the promise of behavioral markers for early AD. Prior theo retical work has suggested that hippocampal dysfunction may selectively impair generalization involving novel recombinations of familiar stimuli. In this study, nondemented elderly individuals were trained on a series of con current visual discriminations and were then tested for transfer when stimulus features were recombined in new ways. Presence or absence of HA, revealed by neuroimaging, was not correlated with concurrent discrimination per formance ; however, individuals with mild HA showed significant decreases in transfer performance relative to nonatrophied participants. These preliminary results suggest that even very mild degrees of hippocampal atrophy may be associated with subtle behavioral impairments. (J Geriatr Psychiatry Neurol 2002; 15:82-90).