1. A method for classifying a brain, the method comprising: processing image data including a brain cortex to generate segmented image data for the brain cortex; generating a three dimensional (3D) model of the brain cortex based on the segmented image data; using at least one processor, performing spherical harmonic shape analysis of the 3D model, including computing a number of spherical harmonics required to delineate a unit sphere to the 3D model; and classifying the brain cortex based on the number of spherical harmonics required to delineate the unit sphere to the 3D model.