This article describes a protocol for inducing psychological stress in participants, which enables researchers to measure psychological, physiological and neuroendocrine responses to stress within single participants or between groups.
This article demonstrates a psychological stress protocol for use in a laboratory setting. Protocols that allow researchers to study the biological pathways of the stress response in health and disease are fundamental to the progress of research in stress and anxiety.1 Although numerous protocols exist for inducing stress response in the laboratory, many neglect to provide a naturalistic context or to incorporate aspects of social and psychological stress. Of psychological stress protocols, meta-analysis suggests that the Trier Social Stress Test (TSST) is the most useful and appropriate standardized protocol for studies of stress hormone reactivity.2 In the original description of the TSST, researchers sought to design and evaluate a procedure capable of inducing a reliable stress response in the majority of healthy volunteers.3 These researchers found elevations in heart rate, blood pressure and several endocrine stress markers in response to the TSST (a psychological stressor) compared to a saline injection (a physical stressor).3 Although the TSST has been modified to meet the needs of various research groups, it generally consists of a waiting period upon arrival, anticipatory speech preparation, speech performance, and verbal arithmetic performance periods, followed by one or more recovery periods. The TSST requires participants to prepare and deliver a speech, and verbally respond to a challenging arithmetic problem in the presence of a socially evaluative audience.3 Social evaluation and uncontrollability have been identified as key components of stress induction by the TSST.4 In use for over a decade, the goal of the TSST is to systematically induce a stress response in order to measure differences in reactivity, anxiety and activation of the hypothalamic-pituitary-adrenal (HPA) or sympathetic-adrenal-medullary (SAM) axis during the task.1 Researchers generally assess changes in self-reported anxiety, physiological measures (e.g. heart rate), and/or neuroendocrine indices (e.g. the stress hormone cortisol) in response to the TSST. Many investigators have adopted salivary sampling for stress markers such as cortisol and alpha-amylase (a marker of autonomic nervous system activation) as an alternative to blood sampling to reduce the confounding stress of blood-collection techniques. In addition to changes experienced by an individual completing the TSST, researchers can compare changes between different treatment groups (e.g. clinical versus healthy control samples) or the effectiveness of stress-reducing interventions.1
1. Set Up
2. Pre-stress Measurements
3. The TSST
4. Post-stress Recovery Measurements
5. Data Analysis
6. Optional: Additional Salivary Cortisol Assay Protocol Information (reproduced from Salimetrics salivary cortisol assay kit insert)
7. Representative Results:
The representative data presented here is compiled from a review of the literature and two studies that were conducted in our lab during the afternoon with healthy adult male participants. These data are intended to approximately represent the results that might be found using the protocol presented in this article.
This TSST protocol (Figure 1) induces increases in self-reported anxiety (as measured by the State Trait Anxiety Inventory; Figure 2), heart rate (Figure 3), and salivary cortisol concentrations (Figure 4). The experimental protocol illustrated in Figure 1 is meant to provide one example of how various measurements might be made during a data collection session with the TSST. The timing of measurements and the inclusion of different measures will be dictated by the specific research question. If using an intervention that is intended to reduce anxiety and/or stress response, blunted or attenuated increases in these measures are predicted.
Figure 1. Experimental protocol. Note: Trier Social Stress Test (TSST); State Trait Anxiety Inventory (STAI); 5-minute Pre Stress period (PS); 10-minute Anticipatory Stress period (speech preparation) (AS); 5-minute Speech period (S); 5-minute Math period (M).
Figure 2. Representative state anxiety scores. Note: State Anxiety score calculated from 20-iten state anxiety measure of State Trait Anxiety inventory (STAI). Representative scores reflect data collected in our lab and published in literature.
Figure 3. Representative heart rate data. Note: Heart rate in beats per minute (BPM). Representative values reflect data collected in our lab and published in literature.
Figure 4. Representative salivary cortisol data. Note: Cortisol concentration in uL/dL. Representative values reflect data collected in our lab and published in literature.
In this article, we demonstrated how to conduct the Trier Social Stress Test in a healthy volunteer. The TSST is a standardized laboratory social stressor that induces robust and reliable increases in psychological, physiological and neuroendocrine measures. The TSST is a useful alternative to physical stressors such at the cold presser test or treadmill walking, and reproduces the more naturalistic psychological stress of performance in the presence of an evaluative audience.
Many aspects of the TSST can be modified to meet the needs of various research programs. The measurement time points demonstrated in this article represent a minimum of sampling. Many experiments may require additional sampling points and measurements to best capture changes in stress response. The length of the anticipatory, speech and math periods (generally ranging from 5-10 minutes), the inclusion or omission of recovery period(s), and the composition of the evaluative audience during the speech and math performances (ranging from a video camera to a panel of evaluators) can be modified. The TSST can be administered to groups as well as individuals.7 Additional measures of HPA- or SAM-axis activation, activity of the sympathetic and parasympathetic nervous system, or psychological self-report of stress can be included to assess response to the TSST. For example, some research groups may find it useful to measure heart rate variability, electrodermal response, blood pressure, startle or eye blink response, or changes in body temperature in response to the TSST. For a review of measures commonly used to assess autonomic nervous system activity, please see Mendes, 2009.7 Recently, some research groups have also begun to investigate changes in immune response to the TSST.8 Many options for assessing psychological response to the TSST are also available (e.g. the Profile of Mood States, visual analogue scales, or Likert-type ratings of stress, anxiety or relaxation).
Differences in individual response to the TSST are an important concern when using this protocol. In healthy adult samples, the TSST has been reported to increase salivary cortisol levels two to three fold in approximately 70-80% of participants, however responses vary widely among individuals.1 Researchers have documented effects of age,1 gender,9, 10 birth weight,11 resilience/attachment style,12, 13 childhood abuse,14 education,15 personality traits,16 use of nicotine/alcohol/caffeine1 or use of medications (particularly sedatives, anxiolytics or hormone-based contraceptives),17, 18 cognitive behavioral therapy,19 compassion meditation,8 and the presence of music20 on TSST response in healthy populations. Recently, researchers have suggested measurements that are taken prior to a waiting period before the TSST are important and may reveal information about individual stress reactivity.21 For a more thorough discussion of individual differences in assessment of salivary hormones, and overview of the use of salivary hormone assessment in social neuroscience, see Schultheiss & Stanton, 2009.22 For a more detailed presentation of individual differences in TSST performance, see Kudielka et al., 2009.23
In addition to individual differences, cortisol is subject to circadian fluctuation, with high levels in the morning then decreasing through the day. If cortisol changes will be used as a measure in response to the TSST, it is important to collect samples at consistent time points for accurate analysis and to avoid confounding TSST-induced cortisol changes with the cortisol response that occurs upon awakening in the morning.
Although many reports have focused on using the TSST to study stress response in healthy, adult populations, this protocol is appropriate for use in clinical populations and has been adapted for use with children.24 This protocol may contribute to important understanding about the role of various biological pathways involved in stress-related disorders or developmental variability of the stress response.
The authors have nothing to disclose.
Thank you to Jessica Ottmar for protocol suggestions and contributions to the representative data. Special thanks to Sabrina Blackledge, Lauren Kohoutek and Kerisa Shelton for demonstrating this protocol.
Name of the equipment/Supply | Company | Catalogue number |
---|---|---|
BSL Psychophysiology System, Mac OS Including MP36 Data Acquisition Unit and three lead electrocardiogram electrodes | BioPac Systems Inc. | BSLPSY-M |
State Trait Anxiety Inventory | Mind Garden, Inc. | STAID-B |
Salivary Cortisol Enzyme Immuno Assay Kit | Salimetrics | 1-3002 |
2.0 ml polypropylene vials | Fisher Scientific | 05 40B 146 |
BioRad Microplate Reader, Model 680, with Microplate Manager software | BioRad | Plate Reader: 168 1000 Software: 1706800 |