Topography of brain atrophy during normal aging and Alzheimer's disease.

The present study investigated the effect of age on total and regional brain volumes and compared age-associated changes in 20 healthy controls with those observed in 12 patients with Alzheimer's disease (AD). Weights and volumes of the whole brain and cerebrum, as well as the fractional volumes of the frontal, temporal, and parieto-occipital cortices, medial temporal structures, deep brain structures, and white matter were measured. Males had larger and heavier brains than females of comparable age. A small decline in brain volume with age was found (approximately 2 ml per year), but only within the white matter. In comparison, no further loss of white matter occurred in AD; however, the cerebral cortex was significantly reduced in volume, with the greatest loss from the medial temporal structures. This loss was related to disease progression; greater proportional loss was associated with more rapid decline in older patients. This study suggests that significant brain atrophy is not a consequence of advancing age. In addition, it suggests a regional specificity of damage in AD.