Neuropharmacology and receptor studies in the elderly

Functional brain imaging has provided unique and exciting opportunities to strengthen our knowledge of the biologic substrate of the aging brain and n europsychiatric disorders. Positron emission tomography (PET) is a particul arly powerful tool for quantifying the neurobiologic correlates of cognitio n, mood, and behavior. Initial PET studies of aging, psychiatric disorders, and neurodegenerative disease focused primarily on generalized physiologic parameters such as cerebral blood flow and metabolism, and early neurorece ptor imaging studies relied on relatively nonselective markers. New, select ive receptor radioligands now offer a previously inaccessible means to inve stigate the dynamic relationships among neurochemistry, aging, and psychopa thology in vivo. This approach has substantial advantages over peripheral ( platelet and cerebrospinal fluid) markers, neuroendocrine challenge studies , animal models, and postmortem receptor binding assays. Advances in tracer kinetic modeling, magnetic resonance imaging facilitated PET image analysi s, radiochemistry techniques, instrumentation, and image processing have he lped pave the way for increased emphasis on functional imaging studies of n europsychiatric disorders. The capability to correct PET image data for the confounding effect of cerebral atrophy permits relationships among age-rel ated brain changes and neurobiologic disease mechanisms to be more accurate ly examined in the elderly.