Reward‐related cognitive vulnerability to bipolar spectrum disorders

Bipolar spectrum disorders (BSDs) are characterized by extreme swings of mood (euphoria or irritability versus sadness), cognition (grandiosity and racing thoughts versus worthlessness and concentration difficulties), and behavior (supercharged energy and excessive goal-striving versus anhedonia and lethargy) occurring within the same individual. They are prevalent, associated with significant disability, and occur on a continuum of severity, from milder cyclothymia to bipolar II to full-blown bipolar I disorder. Individuals’ cognitive styles (i.e., the general filters they use to process information and construe events in their lives) may provide vulnerability to BSD symptoms and episodes. Indeed, individuals with BSDs exhibit cognitive styles with certain unique reward-relevant features and these cognitive styles have been shown to predict the onset and course of BSDs. According to the reward hypersensitivity theory, individuals with or vulnerable to BSDs possess a hypersensitive reward system, linked to a dopaminergic fronto-striatal neural circuit subserving approach motivation and goal-directed behavior, that overreacts to goals or reward-relevant cues. This hypersensitivity leads to excessive approach-related affect and incentive motivation in response to life events involving goal-striving and attainment, which in turn leads to hypomanic/manic symptoms. It also can lead to excessive downregulation or decrease in approach-related affect and motivation in response to nonattainment of goals or rewards (e.g., irreconcilable losses or failures), which in turn leads to bipolar depressive symptoms. Thus, a propensity toward excessive reward system activation and deactivation is the hypothesized vulnerability to BSDs in this model. The model also proposes that vulnerable individuals’ reward hypersensitivity leads to behaviors that increase their exposure (via “stress generation” processes) to the very goaland reward-relevant events that, in turn, precipitate excessive responses from their reward systems. To date, extensive self-report, behavioral, cognitive, life event, neurophysiological and neural evidence supports this reward hypersensitivity model of BSDs. High reward sensitivity may be a temperament trait that contributes to the development of reward-relevant cognitive styles. In line with this hypothesis, euthymic bipolar individuals have been found to exhibit a distinctive profile of cognitive styles characterized by perfectionism, self-criticism and autonomy rather than the dependency and approval-seeking styles observed among unipolar depressed individuals. Additionally, controlling for current mood symptoms, individuals with BSDs exhibit higher achievement motivation, goal-attainment dysfunctional attitudes (e.g., “A person should do well at everything”) and ambitious goal-striving styles than controls. The strongest evidence confirming that reward-relevant cognitive styles provide vulnerability to BSDs comes from a prospective study, which found that, controlling for initial mood symptoms and family history of bipolar disorder, adolescents with no prior history of BSD who exhibited an ambitious goal-striving cognitive style at baseline had a greater likelihood and shorter time to first lifetime onset of BSD than those without that cognitive style. Additionally, a cognitive style characterized by ambitious goal-striving mediated the predictive association between high self-reported reward sensitivity and shorter time to first onset of BSD in this adolescent sample, further suggesting that ambitious goal-striving is a vulnerability trait to BSDs that may account for some of the risk associated with reward sensitivity. Ambitious goal-striving cognitive styles, perfectionism, and a tendency to overgeneralize from success (rewards) have also been observed in individuals with no prior history of BSD but at behavioral risk for developing a bipolar disorder. Further, controlling for baseline hypomanic symptoms, a cognitive style to overgeneralize from success interacted with self-reported reward hypersensitivity to predict increases in hypomanic symptoms among adolescents with no prior history of BSD. Reward-relevant cognitive styles also affect the course of BSDs. In individuals with bipolar I disorder, ambitious goalstriving for financial success and popular fame predicted increases in manic symptoms over a three-month follow-up. In addition, controlling for past history of mood episodes and baseline symptoms, late adolescents with bipolar II disorder or cyclothymia who possessed self-critical or autonomous reward-relevant cognitive styles at baseline had a greater likelihood of hypomanic and manic episodes over a three-year follow-up than adolescents who did not exhibit these styles. Moreover, an autonomous cognitive style mediated the predictive association between self-reported reward hypersensitivity and prospective occurrence of hypomanic and manic episodes in this sample. Finally, in the same sample, reward-relevant life events interacted with reward-related cognitive styles to predict bipolar mood symptoms. Specifically, controlling for initial mood symptoms and total number of life events experienced, baseline perfectionistic and self-critical cognitive styles interacted with reward system-activating positive events to predict increases in hypomanic/manic symptoms, and with reward system-deactivating negative events (e.g., certain failures) to predict increases in depressive symptoms over follow-up. Reward-relevant cognitive styles may not always be maladaptive. Indeed, the high achievement motivation and ambitious goal-striving may contribute to high levels of creativity and achievement also exhibited by many individuals with BSDs or at behavioral risk for developing a bipolar disorder. The role of reward-relevant cognitive styles in the onset and course of BSDs has implications for psychosocial interventions for these disorders, particularly for cognitive-behavioral therapy (CBT), which has been shown to have efficacious prophylactic effects for BSDs. There may be added value to CBT interventions that specifically target achievement, ambitious goal-striving, and reward-oriented cognitive schemas in man-