In this project we will examine the basic cognitive and biological mechanisms that contribute to hyper- responsivity to reward in individuals diagnosed with bipolar (BP) disorder. Over the past 30 years, several theorists have conceptualized mania as the manifestation of dysregulation in an underlying neurobiological system, the Behavioral Activation System (BAS). This brain-based motivational system is hypothesized to underlie positive affect and related behaviors in the context of cues for incentive. In general, research supports the BAS model of BP disorder. Elevated BAS sensitivity has been documented both for persons who are at risk of manic episodes and for those with BP disorder, even during remission. That is, both groups report elevated reward sensitivity on self-report scales. Beyond self-reported sensitivity, people at high risk for manic episodes have been found to demonstrate stronger psychophysiological reactions after positive stimuli than those at low risk. Drawing on the BAS model, we have begun to examine more specific cognitive and behavioral components of reward responsivity in BP disorder. We have found that people with BP disorder display greater increases in positive affect, success expectancies, and goal-setting after receiving reward than do those with no disorder. Beyond evidence for group differences, BAS-relevant characteristics have been found to predict increases in mania over time. Evidence to date, then, suggests that remitted BP disorder is associated with greater reward responsivity, and that related processes help predict the course of mania. In study one, at the University of Miami;we will examine cognitive processes that underlie reward responsivity in BP disorder. In study two, at Stanford University, we will examine biological processes that underling reward responsivity in BP disorder. Both studies will involve comparing people with BP-1 disorder in remission against age-, sex-, and employment-status-matched controls with no mood disorders. By pursuing these aims, we hope to elucidate biological and cognitive processes that could trigger manic symptoms in contexts involving reward. Understanding these processes could help identify times when individuals are at increased risk for manic symptoms and strategies to prevent symptoms. Moreover, the planned study is expected to refine neurobiological models of this disorder.
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