SPECIFIC HIPPOCAMPAL VOLUME REDUCTIONS IN INDIVIDUALS AT RISK FOR ALZHEIMERS-DISEASE

Our goal was to ascertain the involvement of the temporal lobe in the preclinical (not yet diagnosable) stages of dementia of the Alzheimer' s type (DAT) by using MRI-derived volumes. We assessed anatomical subd ivisions of the temporal lobe on three groups of carefully screened ag e- and education-matched elderly individuals: 27 normal elderly (NL), 22 individuals with minimal cognitive impairment (MCI), who did not fu lfill DAT criteria but were regarded at high risk for future DAT, and 27 DAT individuals. We found hippocampal volume reductions of 14% for the MCI and 22% for the DAT group compared to the NL group. Utilizing regression analyses and after accounting for gender, head size, age, g eneralized atrophy (CSF), and other temporal lobe subvolumes, the hipp ocampal volume separated NL from MCI individuals, correctly classifyin g 74%. For NL and MCI groups combined the hippocampal volume was the o nly temporal lobe subvolume related to delayed recall memory performan ce. When contrasting MCI and DAT individuals, the fusiform gyrus volum e uniquely improved the ability of the hippocampal volume to separate MCI from DAT individuals from 74 to 80%. Our cross-sectional data sugg est that, within the temporal lobe, specific hippocampal volume reduct ions separated the group at risk for DAT from the normal group. By the time impairments are sufficient to allow a diagnosis of DAT to be mad e, in addition to the medial temporal lobe volume reductions, the late ral temporal lobe is also showing volume reductions, most saliently in volving the fusiform gyrus. (C) 1997 Elsevier Science Inc.