Functional neuroimaging is playing an increasing role in psychiatry and has moved from academic isolation into clinical practice. This review examines the basis for the use of Single Photon Emission Computed Tomography, the most widely available functional modality, in the two important areas of dementia and parkinsonism. Its contribution to the diagnosis and management of patients is discussed and its likely impact in clinical trials indicated. As functional imaging moves closer to those most able to utilise its power its impact in these and other areas of psychiatry and neurology will increase further.
