Neuroimaging in dementia and depression

John O’Brien is a Senior Lecturer in Old Age Psychiatry at the Institute for the Health of the Elderly (Wolfson Research Centre, Newcastle General Hospital, Westgate Road, Newcastle upon Tyne NE4 6BE, Tel: 0191 256 3323; fax: 0191 219 5051; e-mail: j.t.o’[email protected]). Bob Barber is a consultant psychiatrist and Honorary Lecturer in Old Age Psychiatry at the Centre for the Health of the Elderly at Newcastle General Hospital. Neuroimaging is traditionally divided into structural and functional imaging. Structural imaging looks at brain structure or anatomy and includes computed tomography (CT) and magnetic resonance imaging (MRI). Functional techniques seek to examine the physiological functioning of the brain, either at rest or during activation, and include single photon emission computed tomography (SPECT), positron emission tomography (PET), MRI spectroscopy, functional MRI (fMRI) and encephalographic brain mapping. Although fMRI, MRI spectroscopy and brain mapping are likely to have clinical applications in the near future, the main imaging modalities of current clinical relevance to psychiatrists are CT, MRI and SPECT, which will be the focus of this article.