Over the past ten years, research has elucidated the important role of stress in psychopathology and physical illness. Investigators in this field have used a variety of paradigms, including naturalistic and experimental designs, and have measured both psychological and biological indicators of stress.

In experimental studies, stress has been induced by exposing the research participants to aversive sensory stimuli or psychological experiences. Commonly used sensory stimuli are noise and exposure to extreme temperatures. Psychological stressors have included demanding cognitive tasks and social evaluation. However, the most commonly used psychological stressor has been the Trier Social Stress Test (TSST; Kirshbaum, Pirke, & Hellhammer, 1993). This paradigm was designed by the Kirschbaum laboratory in Germany in the early 1990s, and various derivatives of it have been used to induce stress in over 20 published investigations.

The TSST is a social and cognitive stressor. It involves making a speech and performing an oral arithmetic task in front of an audience. Participants are told they will make a five-minute speech about why they are good candidates for an open job position. They are given 10-minutes to prepare their speech and then they give their speech in view of 2-3 adult judges while being video- and audio-taped. After completing the speech, participants must orally subtract one number repeatedly from a large number for five-minutes. If they make a mistake, they must begin again. The total stressor duration is 20-minutes.

Cortisol, a neurohormone released when the stress system is aroused, is often used to index stress responsivity. When humans perceive an event as stressful, a cascade of physiological events occurs along the hypothalamic-pituitary-adrenal (HPA)-axis, which result in cortisol release. The HPA-axis has been the focus of significant research in the past decade, because it appears to play a pivotal role in physical and mental illnesses. It is well established that, under normal conditions, cortisol release follows a circadian rhythm, whereby it is highest in the morning and decreases throughout the day in the absence of a stressor. Thus, if cortisol release were depicted on a graph, it would appear as a negatively sloping line.

Reports from the Kirschbaum laboratory show a robust cortisol response after presentation of the TSST. Published data indicate that cortisol overrides the diurnal decline in response to the TSST, resulting in a steep positively sloping line (Kirschbaum, Kudielka, Gaab, Schommer, & Hellhammer, 1999; Kirschbaum, Strasburger, & Langkrak, 1993). While studies from the Kirschbaum laboratory consistently show this robust pattern, reports from other research teams vary, with some showing a significant cortisol increase (Altemus, Redwine, Leong, Yeung-Mei, Porges, & Carter, 2001) and others failing to replicate this pattern (Jones, Rollman, & Brooks, 1997; Young, Lopez, Murphy-Weinberg, Watson, & Akil, 2000).

The purpose of the current study was to administer the TSST paradigm in an attempt to replicate the Kirschbaum laboratory findings. All aspects of the procedures outlined by the Kirschbaum laboratory were followed explicitly. Participants were given 10-minutes to prepare a speech and then gave their presentation in front of a panel of 2 judges while being video- and audio-taped. After the speech, they performed the oral arithmetic task, also in front of the judges while being recorded. Saliva cortisol samples were taken at regular intervals to assess the pattern of cortisol release during and after the stress-induction task. It was predicted that cortisol release would override the dirurnal decline of cortisol after exposure to the TSST paradigm.

Method

 Participants

Participants were 14 undergraduate students (13 female) from a southeastern university. The age range of the sample was 18-21 (M=19.21, SD=.89 ) and included the following ethnic categories: African American (N=5), Caucasian (N=8), and Asian (N=1). Participants were recruited from introductory psychology classes. They were asked to refrain from consuming alcohol and caffeine, exercising rigorously and smoking the night before their participation.

 

Measures

Salivary cortisol sampling. Saliva cortisol samples were taken at 11 points, every six minutes, during the study session. Lemon crystals were used to induce saliva. After saturating a cotton ball for one minute, participants placed it directly into a specimen tube provided.

Stress-induction paradigm. Participants were told that after a preparation period, they would take the role of a job applicant and give a speech for five minutes. They were instructed to introduce themselves and convince a panel of judges that they are the best candidate for a job opening. Furthermore, they were told the judges were specially trained to monitor their nonverbal behavior, and later a voice frequency analysis and an evaluation of their speech performance would be conducted. Following these instructions, participants were given 10 minutes to prepare their speech during which time they could make notes using paper and pencil provided; however, they were not allowed to use any notes during the actual speech.

After the speech preparation period, participants were asked to give their speech in front of two judges while being video- and audio-taped for 5-minutes. After the speech, they were asked to subtract the number 13 from 1022 as quickly as possible without making any mistakes. If they made a mistake, one of the judges said, "Stop. 1022," indicating participants should start the task over. The arithmetic task lasted 5-minutes.

 

Procedure

 All testing was conducted individually during the morning hours (9-10:30am) to minimize the effects of individual differences in the diurnal rhythm of cortisol. Participants gave a saliva cortisol sample every 6^th minute during the experiment. Individuals signed the informed consent form and then practiced paired associate memory tests; these were given before and after the stressor but results will not be reported in the current paper. Participants answered questions regarding their compliance with the study restrictions.

Results

Cortisol levels were significantly positively intercorrelated across time. Correlations among successive cortisol values ranged from r= .85-.99, with all significant at the .01 level, indicating good reliability in the cortisol data.

A repeated-measures analysis of variance with cortisol as the dependent variable and time as the independent variable was conducted. The time variable represented the 7 cortisol values from sampling every 6-minutes, beginning with baseline (before stressor onset) through 12 minutes after the stressor ended. Results revealed that cortisol level did not significantly change over time after the stressor began, F(6, 6)=.90, p=.55 (see Figure 1). Thus, contrary to the hypothesis, cortisol did not significantly increase or override the diurnal decline of cortisol after exposure to the TSST. These results do not replicate the Kirschbaum laboratory findings.

 

Altemus, M., Redwine, L. S., Leong, Y-M, Frye, C. A., Porges, S. W., & Carter, C. S. (2001). Responses to laboratory psychosocial stress in postpartum women. Psychosomatic Medicine, 63, 814-821.

Jones, D. A., Rollman, G. B., & Brooke, R. I. (1997). The cortisol response to psychological stress in temporomandibular dysfunction. Pain, 72, 171-182.

Kirschbaum, C., Kudielka, B. M., Gaab, J., Schommer, N. C., & Hellhammer, D. H. (1999). Impact of gender, menstrual cycle phase, and oral contraceptives on the activity of the hypothalamic-pituitary-adrenal axis. Psychosomatic Medicine,61(2), 154-162.

Kirschbaum, C., Pirke, K.-M., & Hellhammer, D. H. (1993). The Trier Social Stress Test- A tool for investigating psychobiological stress responses in a laboratory setting. Neuropsychobiology, 28, 76-81.

Kirschbaum, C., Strasburger, C. J., & Langkrar, J. (1993). Attenuated cortisol response to psychological stress but not to CRH or ergometry in young habitual smokers. Pharmacology, Biochemistry and Behavior, 44, 527-531.

Young, E. A., Lopez, J. F., Murphy-Weinberg, V., Watson, S. J., & Akil, H. (2000). Hormonal evidence for altered responsiveness to social stress in major depression. Neuropsychopharmacology, 23(4), 411-418.

 

Figure 1.

Cortisol Release After Exposure to the TSST

 

Posted: June 11, 2002

Manuscript Correspondence to:

Anna Bollini

Department of Psychology, Emory University

Atlanta, GA 30322

abollini@learnlink.emory.edu

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