| College students tend to gain weight, increasing their risk for obesity and related health
outcomes. One possible explanation of weight gain in college students is high stress levels,
which is linked to increased consumption of food and obesity. One proposed mechanism linking
stress to overeating involves activation of the hypothalamic-pituitary-adrenal (HPA) axis,
resulting in cortisol release and downstream dopaminergic activity, both of which are implicated
in reward processing and delay discounting (DD). DD refers to a pattern of preference for
smaller, sooner rewards over those that are larger and delayed. Therefore, it is possible that stress
may increase DD of food rewards via dopaminergic pathways triggered by cortisol. The present
study examined the extent to which acute stress or a control condition increased DD among
college students with low vs high levels of chronic stress. College students (N = 76) were
categorized into low or high chronic stress groups using the Trier Inventory for Chronic Stress.
Participants completed baseline food and monetary DD tasks and were then randomly assigned
to either an acute stress condition (Trier Social Stress Test; TSST) or a control condition before
completing post-manipulation DD tasks. The acute stress manipulation was validated, as
significant increases in subjective stress and heart rate were observed relative to the control
condition. Magnitude effects were observed with baseline DD measures, as smaller rewards were
discounted more steeply than larger rewards, replicating previous studies. Importantly,
individuals with high chronic stress showed greater DD for monetary rewards, though no relation
to food rewards. This effect was stable across timepoints, suggesting trait-like differences in
STRESS AND DELAY DISCOUNTING
reward valuation. Contrary to hypotheses, acute stress did not alter DD for either food or
monetary outcomes, suggesting insensitivity to state-dependent effects. Overall findings indicate
that acute stress is insufficient to shift discounting rates, while chronic stress is more consistently
associated with DD. These results show the importance of considering chronic stress in future
discounting research and suggests that interventions targeting discounting rates may benefit from
focusing on chronic stress exposure rather than acute stress.
Keywords: cortisol, delay discounting, food, obesity, stress, TSST |