Future Directions for Understanding Adolescent Bipolar Spectrum Disorders: A Reward Hypersensitivity Perspective

Abstract

The idea that bipolar spectrum disorders (BSDs) are characterized by enhanced sensitivity to rewarding stimuli is at the core of the reward hypersensitivity model, one of the most prominent and well-supported theories of BSDs. In this article, we present the reward hypersensitivity model of BSDs, review evidence supporting it, discuss its relevance to explaining why BSDs typically begin and consolidate during the period of adolescence, and consider three major unresolved issues for this model that provide important directions for future research. Finally, we present integrations of the reward hypersensitivity model with circadian rhythm and immune system models that should provide greater understanding of the mechanisms involved in BSDs, and then suggest additional directions for future research deriving from these integrated models.

The Interplay Between Reward-Relevant Life Events and Trait Reward Sensitivity in Neural Responses to Reward Cues

“…For example, according to the reward-hypersensitivity model of BSDs (Fig. 1; Alloy et al, 2016; Alloy & Nusslock, 2019; Depue & Iacono, 1989; Johnson et al, 2012; Nusslock & Alloy, 2017), people with a hypersensitive reward system excessively respond to goal- or reward-relevant cues. This reward hypersensitivity is hypothesized to lead to extreme approach-related affect (e.g., excitement, elation, or anger) and incentive motivation following exposure to specific life events.…”

“…The brain’s reward system subserves approach motivation and pursuit of rewards and goals (e.g., Haber & Knutson, 2010). The reward-hypersensitivity theory (Alloy & Abramson, 2010; Alloy et al, 2016; Alloy & Nusslock, 2019; Depue & Iacono, 1989; Johnson et al, 2012; Nusslock & Alloy, 2017), often applied to bipolar spectrum disorders (BSDs), hypothesizes that individual differences in trait sensitivity to rewards will combine with individuals’ exposure to life events that tend to activate or deactivate the reward system to influence state levels of reward responsivity. However, to our knowledge, as yet, no work has precisely tested these hypotheses.…”

Reward Sensitivity, Cognitive Response Style, and Inflammatory Response to an Acute Stressor in Adolescents

“…Both high and low reward sensitivity (conceptualized as the strength of reward processing and approach motivation) have been associated with elevated inflammation (see Nusslock & Miller, 2016 for a review). One potential way that elevated reward sensitivity could influence inflammatory profiles is by increasing the salience of goal-pursuit or failures (see Alloy & Nusslock, 2019, which also described potential mechanisms linking inflammation and reward sensitivity that are beyond the scope of this paper). In particular, reward drive, the facet of reward sensitivity that involves the intensity with which one pursues goals and desired outcomes, might be associated with inflammatory stress reactivity to reward/goalassociated stressors.…”

“…The immunocognitive model (Moriarity, et al, 2018) posits that perseverative response styles amplify the effect of arousal-related characteristics on inflammation in ways that increase risk for negative outcomes (specifically mood psychopathology). Given that individuals with high reward drive tend to experience heightened arousal during goal pursuit and perceive reward or performance-related stressors to be more salient (Alloy & Nusslock, 2019), it is plausible that perseverating on negative affect during goal-oriented stress amplifies the association between reward drive and inflammatory stress responses. Moriarity, Ng, and colleagues (in press b) found initial support for the interaction between reward sensitivity and ruminative response style as a predictor of resting levels of inflammatory proteins in young adults (specifically, C-reactive protein and interleukin-8).…”

Smoking as a Common Modulator of Sensory Gating and Reward Learning in Individuals with Psychotic Disorders

“…A second aim was to compare associations in individuals with schizophrenia to individuals with psychotic bipolar disorder. This is an important comparison because although individuals with bipolar disorder share genetic susceptibility with schizophrenia [ 51 ], experience perceptual disturbances and P50 sensory gating deficits [ 24 , 52 ], and show high rates of smoking [ 53 ], several theoretical models (for reviews, see [ 4 , 54 , 55 ]) and recent empirical studies [ 56 ] suggest a distinct profile of motivational disturbances in bipolar disorder that are potentially attributable to elevated (as opposed to blunted) reward responsiveness. Accordingly, individuals with bipolar disorder may differ from individuals with schizophrenia on important aspects of reward-based prediction and prediction error signaling.…”