Biological Response to Brief Psychological Challenge

The proposed study will examine physiologic responses to acute psychological challenge in the laboratory among healthy adults. It is widely accepted that there is an increase in circulating markers of inflammation following a single bout of laboratory stress. This increase in systemic inflammation is believed to contribute to the damaging health effect of psychological stress. However, to date, the biological mechanisms by which psychological stress is transduced into inflammation are unclear. The investigators' preliminary evidence suggests that mitochondrion may play a role, with stress-induced increases in circulating levels of mitochondria- derived signaling molecules that are known to modulate immune cell function and the production of pro-inflammatory cytokines. To test this possibility, the investigators plan to conduct a crossover experimental trial examining physiological responses to an evaluative speech task under laboratory conditions. The investigators have previously used this task to induce physiological arousal. The investigators plan to recruit 60 non-smoking volunteers (50% female, aged 20-50 years) and test these participants on two occasions separated by at least a month. On one occasion the participants will be exposed to the speech task. On the other occasion, the participants will rest quietly for the same period. Conditions will be counterbalanced. At both visits cardiovascular responses (heart rate, blood pressure, and heart rate variability) will be assessed as measures of autonomic activation before, during and after the task period. Participants will also have an intravenous catheter inserted and blood drawn at ten time points over the two hour testing period on each occasion. Blood samples will be sent to laboratories at the University of Pittsburgh and at Columbia University for the assessment of mitochondria-derived signalling molecules, inflammatory markers, and cortisol levels.