1. A system for automated differential diagnosis of dementia, including: a knowledge base that comprises a plurality of brain scan images exhibiting patterns of a plurality of types and degrees of dementia and one or more healthy brain scan images; a processor configured to: receive information related to a patient's brain scan image having at least one hypometabolic region; generate feature vectors for a statistical map of the patient's brain scan image, the statistical map showing one or more statistically significant hypo-metabolic regions; weight the feature vectors to indicate a relative ability of individual vectors to differentiate between types of dementia; compare the statistical map of the patient's brain scan image to the brain scan images in the knowledge base; and identify a brain scan image in the knowledge base having a hypo-metabolic region pattern similar to the statistical map of the patient's brain scan image; and a user interface to which dementia diagnosis information is output for user review; wherein the diagnosis information includes an image of the patient's brain scan image with highlighted hypo-metabolic regions; wherein the highlighting is color-coded to indicate a type of dementia; wherein different colors correspond to different types of dementia.