Do positive emotions predict symptomatic change in bipolar disorder

Bipolar disorder (BD) is a chronic psychiatric illness associated with profound functional impairment and morbidity (1). Despite advances in treatments (2), the risk of relapse remains high. Thus, it is important to refine our understanding of mechanisms that may contribute to interepisode dysfunction and predict subsequent relapse. Several lines of evidence converge to suggest the importance of positive emotional disturbance in BD. First, one hallmark feature of BD is an abnormally elevated mood characteristic of periods of mania (3, 4). Second, people at risk for BD (as defined by high scores on self-report screens) and those diagnosed with BD exhibit heightened positive emotional responses (5). For example, two studies demonstrated that BD is associated with greater self-reported excitement at the prospect of earning rewards compared to controls (6, 7). People at high risk for BD exhibit more robust startle eye-blink attenuation to positive photos, an indirect marker of positive affect, compared to low-risk participants (8). At-risk BD samples also report greater positive affect and exhibit elevated cardiac vagal tone, an autonomic correlate of positive emotion, across distinct types of emotional films (9). Third, experience-sampling studies suggest that people with BD reported elevated positive affect across many different contexts in their daily lives compared to controls (10). Taken together, these studies suggest that BD may be associated with elevated positive emotionality. Despite robust findings, prior work on positive emotion in BD has tended to assess positive emotion in terms of one-dimensional ‘happiness’ or ‘positivity’ constructs. Recent work in affective science has supported the validity of differentiating multiple positive emotions (11–13) that broaden and build cognitive and social resources (11, 14). Indeed, four distinct positive emotions have begun to receive empirical attention; these include pride, compassion, happiness/joy, and amusement. First, pride is a self-oriented emotion that signals elevated status, relevant for negotiating social hierarchies (14–16). Compassion [also referred to as sympathy (17)] is conceptualized as an other-oriented emotion that promotes shifting attention away from oneself and toward vulnerable individuals (18, 19). Happiness/joy is a reward-oriented emotion that refers to the high-arousal state felt when the environment signals an imminent improvement in resources, and one must expend energy to acquire reward (13, 14, 20, 21). Amusement, a knowledge-oriented emotion, is experienced during a cognitive shift from one knowledge structure to another, such as during a joke’s punch line, and is thought to facilitate creative thinking (22, 23). Three positive emotions that have received less empirical support are love, awe, and contentment. Love is a multifaceted term that includes the positive component of Bowlby’s attachment behavioral program (e.g., 18). Awe has been discussed as an emotional response to novel and complex stimuli that current knowledge structures must assimilate (24). Finally, contentment is experienced when one’s resource needs have been satisfied (11). Given these varieties of positive emotion, where might we expect to see more fine-grained deficits in BD? Our research group has completed two studies implicating specific positive emotions in BD. Results indicated that people at risk for BD report greater state and trait joy and pride relative to compassion (9, 25). These findings dovetail with a growing literature suggesting that risk for BD involves a heightened focus on the pursuit of rewards and achievement of ambitious goals (26). No studies, however, have yet examined specific positive emotions in a clinically diagnosed BD sample. Furthermore, few studies have examined associations between positive emotion and clinical course in BD. Initial evidence, however, suggests that self-reported sensitivity to reward predicts increases in manic symptoms (7, 26). It will be important to ascertain the role positive emotion plays in predicting symptom severity and function in BD.