Introduction     Diagnosis of Mild Cognitive Impairment and Alzheimer's Disease Karen L. Bell, M.D.     Treatment Strategies for Dementia and Mild Cognitive Impairment Mary Sano, Ph.D.     Treatment of Depression, Agitation, and Psychosis in Dementia Davangere P. Devanand, M.D.     Recognition of Vascular Dementia, Dementia with Lewy Bodies, and Frontotemporal Dementia Lawrence S. Honig, M.D., Ph.D.     Neuropsychology of Mild Cognitive Impairment, Alzheimer's Disease, Dementia with Lewy Bodies, and Frontotemporal Dementia Penne Sims, Ph.D.     Neuroimaging in Dementia Scott A. Small, M.D.     Neurobiological Correlates       Metabolism in Imaging       Imaging Modalities       Diagnostic Specificity       Early Detection     Genetics of Neurodegenerative Disease: Alzheimer's Disease, Frontotemporal Dementia Jennifer Williamson-Catania, M.S.     Legal and Ethical Issues for Patients with Dementia Daniel G. Fish, Esq.     Posttest         Accreditation     Reference List     Acknowledgements		Neuroimaging in Dementia Scott A. Small, M.D. Metabolism in Imaging   The kinds of techniques we typically call functional imaging, including fMRI, PET, and SPECT, are probably the types of imaging that generate the most excitement. What is the function in functional imaging?   In 1945, Kety and Schmidt used a fixed principle to first quantitate cerebral blood flow in an area of the brain. In their first studies they did not take images, but rather measured input and output in the whole brain. Their fixed principle underlies most imaging today, and that is that brain metabolism is proportional to cerebral blood flow and to cerebral blood volume, and is inversely proportional to the amount of deoxyhemoglobin.         Brain Function and Brain Metabolism   Acute and chronic changes in metabolism correspond to two basic properties of neurons (bioelectricity and biochemistry) and to the two main physiological components of brain function (synaptic activity and synaptic strength). Courtesy of Dr. Scott Small     The function in functional imaging refers to metabolism. However, the brain is never in a steady state, so metabolism by definition is dynamic. Historically, metabolism has been divided into acute changes in metabolism—changes that occur over seconds—versus chronic changes that occur over minutes, hours, or longer.   These correspond nicely to two basic properties of the neuron. The first is bioelectricity: any acute change in bioelectricity will change acute metabolism, reflected as a spike in activity. The second and greater determinant of metabolism is biochemistry. This term includes the processes that are important for learning and memory and that are presumably targeted by most causes of dementia, including Alzheimer's, and memory decline associated with aging. These two properties map to the two main physiological components of brain function: bioelectricity to synaptic activity, and biochemistry to synaptic strength.   With this scheme in mind, the terms functional imaging and structural imaging can be confusing; if we use PET to measure a receptor, is that function or structure? If we use spectroscopy to measure a certain constituent of the neuron that is important for normal physiologic function, is that function or structure? Because of this confusion, these terms are now falling out of use.     PREVIOUS | NEXT