Date of Award

2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Clinical Psychology (PhD)

Department

Clinical Psychology

First Advisor/Committee Member

Amy Mezulis

Second Advisor/Committee Member

Sheila Crowell

Third Advisor/Committee Member

Thane Erickson

Abstract

There is a well-documented relationship between stress and depression, although only recently has the field begun to articulate clear models regarding how stress exerts this effect. One prominent model highlights the disruptive impact of stress on reward processing, which relates to anhedonia – a cardinal symptom of depression. Vulnerability-stress models also play an important role in depression research and hold that individual differences in responses to stress may exacerbate the relationship between stress and depression. Pre-ejection period (PEP) reactivity to reward has been posited as an index of reward sensitivity and approach motivation and has been increasingly linked to depression. However, little research has examined the pathways to disrupted PEP responding. The current study examined PEP reactivity to reward as a mediator between stress and self-reported anhedonia symptoms. In addition, I examined whether individual differences in respiratory sinus arrhythmia reactivity to stress affected the impact of stress on PEP reactivity to reward. Participants were 72 youth, ages 11-15 years (M = 13.28, SD = 0.80). Adolescents completed two visits approximately 6 months apart. During the first visit, youth completed a stressor task while RSA reactivity was recorded. At the follow up visit, youth reported on their stress exposure and depressive symptoms, and they completed a reward activity during which PEP reactivity was assessed. The results of the simple mediation examining the effects of stress on PEP reactivity and anhedonia was not significant (Index of mediation = 0.05; CI [-0.20, 0.15]). There was support for the moderated mediation which examined the interaction between stress reactivity and stress exposure predicting differential effects on PEP reactivity to reward (Index of moderated mediation = -0.11, CI [-0.27, -0.01]). Specifically, stress exposure had a stronger effect on PEP reactivity for youth displaying increased RSA withdrawal to stress while youth with lower levels of RSA responding exhibited no effect of stress on PEP reactivity (b = -2.17; p = .05). In turn, those with smaller PEP changes to reward reported greater anhedonia symptoms (b = .05; p = .04). Although the findings of the study should be considered tentative, the pattern of results appears consistent with theoretical expectations and offer important implications for future research examining PEP and reward sensitivity.

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