Differential effects of acute stress and social anxiety on self-control in younger and older people

The delay discounting paradigma has been shown useful to measure self-control vs. impulsivity on a behavioural level. It has been found that in general older people have lower discounting rates that younger ones, i.e., they are more self-controlled. Aim of the present study is to investigate whether older vs. younger people differ in the degree to which self-control is influenced by acute stress and social anxiety. The sample consists of 72 cognitively healthy, community dwelling participants between 18 and 40 years (mean 23) and 64 between 60 and 80 years (mean 70). The Montreal Imaging Stress Task (MIST) was used to induce acute stress. The MIST is a computerized control and stress task combining challenging arithmetic problems with social-evaluative threat and has previously been found to increase cortisol level, heart rate, and alphaamylase levels, and to reduce respiratory sinus arrhythmia. The Kirby Delay Discounting Questionnaire was used to measure self-control on a behavioural level; participants were offered choices between monetary rewards available immediately and larger rewards available after delays ranging from 1 week to 6 months. A significant stress x anxiety interaction was found in the young sample, but not in the old sample. Younger people with low social anxiety were more self-controlled than people with high social anxiety when not stressed and decreased in their self-control under acute stress. This effect is reversed in the older sample, although not significantly. These results suggest that the effects of stress and social anxiety on self-control might change with age.