A method of diagnosing Lewy Body Dementia in a human patient by assessing the level of dopamine transporter in at least one region of the patients central nervous system, where a lowered level of dopamine transporter in the patient is indicative of Lewy Body Dementia. In embodiments of the invention, assessment of dopamine transporter levels includes assessing binding of a dopamine transporter ligand to the dopamine transporters using PET or SPECT.