The biological effects of acute psychosocial stress on delay discounting.

Organisms prefer to receive rewards sooner rather than later because they excessively discount the subjective value of future rewards, a phenomenon called delay discounting. Recent studies have reported an association between cortisol-which is secreted by the hypothalamic-pituitary-adrenal (HPA) axis-and delay discounting. However, no study has examined whether acutely induced psychosocial stress modulates delay discounting. Thus, the present study examined the effect of acute psychosocial stress and its hormonal and inflammatory correlates on the rate of delay discounting. To accomplish this purpose, we assessed the participants' discounting rates using the questionnaire version with inter-temporal choice before and after an acute psychosocial stress task (the Trier Social Stress Test; TSST). The results demonstrated that TSST increased rates of delay discounting in only cortisol responders (not in non-responders), indicating the possible influence of the pathway from the HPA axis to the dopaminergic systems under acute stress. Furthermore, the findings of correlation analysis indicated a U-shaped relationship between baseline level of C-reactive protein and delay discounting rate, suggesting a complex relationship between inflammatory markers and delay discounting rate.