Biological Response to Brief Psychological Challenge

The investigators plan to conduct a crossover experimental trial examining physiological responses to a socio-evaluative speech task under laboratory conditions. Participants will attend two laboratory sessions. At one session participants will take part in a brief laboratory stress task and at the other participants will rest for the same period. Measures of cardiovascular response will be assessed at both sessions. In addition, blood will be drawn at multiple time points across a 125 minute period to assess changes in circulating levels of cortisol, catecholamines, markers of inflammation and cell free mitochondrial DNA in response to the task. The investigators expect that the stress task will induce a specific increase in ccf-mtDNA, which will statistically mediate subsequent peak circulating Interleukin-6 and Tumor Necrosis Factor-α levels. In secondary analyses, the investigators will examine whether stress-induced increases in circulating cortisol, epinephrine, and norepinephrine levels correlate with increases in ccf-mtDNA. These studies will establish the kinetics and magnitude of psychological stress-induced ccf-mtDNA release, the association with early stress mediators, and whether ccf-mtDNA mediates the inflammatory response to acute stress in humans.