Hormonal and subjective distress comparability of two lab-based stressors : implications and future directions

The CO₂ Challenge is an innate stressor as it acts directly on CO₂ and PH sensitive receptors in the brain. The TSST is a conditioned stressor, e.g. an individual has to learn through experience that they should feel nervous or afraid to perform tasks in front of judges. Given the fundamental difference between the two stressors, the present study explores how comparable the stressors are using testosterone and cortisol reactivity to the CO₂ Challenge, and subjective stress, anxiety, and fear to the CO₂ Challenge and the TSST. Testosterone and cortisol reactivity are shown to interact to predict TSST subjective distress. However, hormonal reactivity to the CO₂ Challenge is not associated with CO₂ Challenge subjective distress, and the subjective distress for the CO₂ Challenge and the TSST are not associated. Different fear pathways in the brain are discussed, with the amygdala appearing to play a bigger role in the subjective distress to the TSST, and CO₂ and PH receptors, sensory cortex, and brainstem seeming to play a larger role in the subjective distress and hormonal reactivity to the CO₂ Challenge. Implications of different stressor circuitry in the brain and future directions are discussed.