The burgeoning field of neuroeconomics, representing the interface between economics, psychology, and neuroscience, offers the opportunity to understand the neural mechanisms underlying a wide variety of human social behaviors. The proposed study, submitted in response to RFA-AG-06-011 Neuroeconomics of Aging (R21), will incorporate economic behaviors, including temporal discounting, risk tolerance, trust, and financial literacy into an ongoing longitudinal epidemiologic clinical-pathologic study of aging, the Rush Memory and Aging Project. We will test the hypothesis that Alzheimer's disease pathology accounts for individual differences in economic behaviors in older persons without dementia. Preliminary data is provided demonstrating that the majority of older persons without dementia accumulate Alzheimer's disease pathology (neurofibrillary tangles and amyloid) in neural systems that sub serve economic behaviors. These include regions that support analytic decision making including the dorsolateral prefrontal cortex, posterior parietal cortex, and anterior cingulate cortex, and regions that support affective decision making including nucleus accumbens, orbital frontal cortex, amygdala, anterior caudate nucleus, and anterior insular cortex. We introduce the term degraded rationality to refer to the consequences of pathological changes in the brain on both economic behaviors. The results have important implications for economic modeling of the economic decisions of older persons. The proposed study offers the possibility of identifying the pathologic basis individual differences in economic behaviors in older persons without clinical dementia. As the U.S. population ages, a greater understanding of economic decision making in old age as it applies to savings behavior, inter-generational transfers, retirement planning, advanced directives, and insurance decisions are needed. The results of the proposed study could lay the foundation for a series of studies that address these and other aspects of economic decision making in older persons without dementia.
