Temporal Stability of Cortisol Reactivity to Stress and Reward Responsivity in the Context of Depression and Anhedonia

Abstract

Theoretical and empirical work suggest that reactivity to stress and responsivity to reward are correlated domains of functioning, and that dysfunction in the stress and reward systems may underlie Major Depressive Disorder (MDD). The goals of the current study are to examine: (1) the longitudinal stability of cortisol reactivity to stress and behavioural reward responsivity; (2) longitudinal changes in cortisol reactivity to stress and behavioural reward responsivity; (3) moderating variables (depression symptoms, anhedonia symptoms, sex, childhood maltreatment, and life stress) in the stability and change of cortisol reactivity to stress and behavioural reward responsivity; and (4) the co-variation of cortisol reactivity to stress and behavioural reward responsivity over time. The current study includes 77 adults (52 with a lifetime history of MDD, 25 never-depressed) who were well-characterized in terms of their diagnostic and symptom profiles, and who participated in a laboratory stress challenge (the Trier Social Stress Task; TSST) and a computerized Probabilistic Reward Task (PRT) at two time points approximately six months apart. My results indicated that there was general stability in both cortisol reactivity to stress and reward responsivity over time (i.e., Time 1 scores significantly predicted Time 2 scores); however, stability was also associated with moderating variables. There were also changes in both cortisol reactivity and reward responsivity over time (i.e., increases or decreases at a group level); however, these changes were related to moderating variables. Finally, my results suggested that cortisol reactivity to stress and behavioural reward responsivity co-varied over time. This is the first study to examine the longitudinal stability of both cortisol reactivity to a social evaluative stress task and behavioural reward responsivity. Further, this study is the first to examine how cortisol reactivity and reward responsivity co-varied across two time points. My findings provided an important foundation in identifying factors that may be relevant in altering the stability of cortisol reactivity and reward responsivity, and suggested that changes in anhedonia symptomatology and exposure to stressful life events may be particularly relevant to the stability of the stress and reward systems over time.