Changes in brain morphology in Alzheimer disease and normal aging: is Alzheimer disease an exaggerated aging process?

BACKGROUND AND PURPOSE Whether Alzheimer disease (AD) represents exaggerated aging rather than a disease is controversial. Data about the effects of normal aging on the human brain are essential for clarifying this issue; however, whether coherent common patterns of regional morphologic brain changes emerge in the normal aged brain is unclear. Clarification of regional morphologic changes in the brain associated with normal aging and AD was sought using MR imaging. METHODS Ninety-two healthy volunteers and 26 mildly to moderately impaired patients with AD participated. Images were anatomically normalized, and voxel-by-voxel analyses were done. RESULTS In healthy volunteers, an age-related decline in the volume of the prefrontal cortex, insula, anterior cingulate gyrus, superior temporal gyrus, inferior parietal lobule, and precuneus was found. These decreases might contribute to the cognitive changes during normal aging. In patients with AD, a significant reduction of gray matter volume in the hippocampal formation and entorhinal cortex bilaterally was noted. CONCLUSION Morphologic changes associated with normal aging are clearly different from those seen with AD.