Image analysis was done on Sun Microsystems, Inc. (Mountainview, CA) workstations using Cardviews software (Caviness et al. 1996).

In brief, structural scans were transferred to the Center for Morphometric Analysis-Charlestown Massachusetts General Hospital and coded and catalogued for blind analysis. Imaging analysis was done by 2 raters on Sun Microsystems, Inc (Mountainview, CA) workstations using Cardviews software.44 The datasets were positionally normalized to overcome variations in head position and then segmented into gray, white, and cerebrospinal fluid (CSF) tissue classes. The segmentation method uses a semiautomated intensity contour algorithm for external border definition and signal intensity histogram distributions for delineation of gray-white borders. Total cerebral volume (TCV) was defined as all tissue in the cerebrum, including CSF, and excluded cerebellum and brain stem