Acute stress potentiates anxiety in humans

Abstract

Background: Stress is an important factor in the development and maintenance of anxiety disorders. Stress also potentiates anxiety-like response in animals, but empirical evidence for a similar effect in humans is still lacking.

Methods: To test whether stress increases anxiety in humans, we examined the ability of a social stressor (speech and a counting task) to potentiate the facilitation of startle in the dark. Measures of subjective distress and of hypothalamic-pituitary-adrenal axis and autonomic nervous system activity (e.g., salivary cortisol, alpha-amylase, blood pressure, and heart rate) were also taken to confirm the effectiveness of the stress manipulation.

Results: Startle was significantly facilitated in the dark. This effect was potentiated by prior exposure to the social stressor. The social stressor induced increases in salivary cortisol and alpha amylase as well as increases in blood pressure, heart rate, and subjective distress.

Conclusion: The findings indicate that stress potentiates anxiety. Animal studies suggest that such an effect might be mediated by glucocorticoid effects on corticotropin-releasing hormone in limbic structures.

Figure 1

Schematic representation of the procedure. Following a 10-min preparation, participants in the social stressor condition gave an 8-min unstructured speech on abortion after which they counted backwardly from 1000 in decrements of 13 for 2 min in front of a male and a female “judge” in white lab coats (total duration of social stressor = 10 min). A video camera relayed the speaker's image to a TV screen that the speaker could see while talking. In the control condition, participants rested for about 20 min. The startle test was initiated twenty minutes after the end of the social stressor. It started with six habituation startle stimuli, immediately followed by the FSD test. The FSD test started with an additional six startle stimuli (under lighted conditions) followed by three alternating 60-sec blocks of startle stimuli delivered under lighted conditions or in complete darkness, counterbalanced across subjects. The saliva samples were collected and BP was measured at the five following time points; prior to speech preparation (t -2 min), immediately after and 9 min after the social stressor (t +23 min and t + 32 min), before startle habituation (t +41 min), and after the dark/light startle test (t + 55 min). In addition, subjects were asked to indicate their level of distress on a Likert scale ranging from 1 (not at all distressed) to 10 (extremely distressed) prior to the speech preparation (t -2 min), just before (t +11 min) and after (t +23 min) the social stressor.

Figure 2

Startle magnitude and facilitation of startle in the dark (difference scores) during light and dark conditions following the stressor or no stressor.