The way a biomarker is conceptualized e. As such, choosing a stress-related biomarker to include in a study depends on the design of the study and the outcomes of interest. Table 3 provides further tools for how to choose the appropriate biomarker. Examples of how stress-related biomarkers can be modeled as either the predictor, the mediator, or the outcome in research studies. Essential questions for following best practices in choosing an appropriate stress-related biomarker.
One area of research that requires particularly careful consideration of biomarker selection is when biomarkers are used as an outcome in psychosocial intervention trials. The scientific community is often eager to find an objective biological indicator that a psychosocial intervention can improve health; this is typically done by measuring improvement in a biomarker from pre- to post-intervention. This approach is problematic for several reasons, including variability in baseline biomarker profiles, unknown reliability of biomarker assessment over time, unknown stability of these changes, and lack of evidence for the long-term impact of small changes in stress-related biomarkers on disease risk.
Therefore, biomarkers should not replace self-report, behavioral, and cognitive outcomes as primary outcomes in psychosocial intervention trials aimed at reducing stress or related goals. Despite stress exposure being an inevitable part of life, not everyone develops stress-related illnesses at the same speed. One primary reason for this is that stress exposures are not distributed evenly across social groups.
Women, young adults, members of racial-ethnic minority groups, divorced and widowed persons, and poor and working-class individuals report greater chronic stress and cumulative stress exposure across their lives Thoits, In addition, recent research has demonstrated that both psychological and physiological stress responses vary remarkably within and between people. Individual-level differences and environmental contexts interact to influence the psychological and physiological stress response trajectories.
These include socioeconomic and cultural factors, genetic and developmental factors, historical and current stressors, stable protective factors, and health behaviors. A model integrating these different levels of experience is presented by our group in detail in Epel et al. Transdisciplinary model of psychological stress: Integrating contextual, historical, habitual, and acute stress processes.
Figure 2 presents a transdisciplinary model that describes psychological stress as encompassing as a set of interrelated processes. These contextual factors include individual-level characteristics such as personality and demographics, the environment in which one lives, current and past stressor exposures, and protective factors—all of which combine to determine the baseline allostatic state of physiological regulation, and the lens through which stressors are perceived and assigned meaning.
Contextual factors and habitual processes together influence psychological and physiological responses to acute and daily stressors. These responses, if dysregulated, are thought to lead to allostatic load and ultimately biological aging and early disease. Reprinted from Frontiers in Neuroendocrinology Epel et al. Advanced statistical models can be used to examine variability in stress responses both psychological and physiological within and between people Bryk and Raudenbush, ; McArdle and Epstein, Between-person variability means that different people respond to the same stressor in a variety of ways.
Cortisol can be used as an example of variability in physiological stress responses Cortisol generally increases in response to laboratory-based acute stress tasks if they are uncontrollable and characterized by social-evaluative threat Dickerson and Kemeny, , such as the TSST described earlier Kirschbaum et al. However, around 30 percent of people do not mount a cortisol response, and there is tremendous variability in the size of the response.
Individual-level predictors of this variability include age, gender, sex steroid levels, smoking, coffee, and alcohol consumption Kudielka et al. Interestingly, these differences are not driven by differences in the emotional responses to the task as acute stressors are not strongly correlated to the physiological responses. In a review of 49 acute stress studies, only 25 percent reported a significant correlation between the two emotional and physiological responses Campbell and Ehlert, Empirical evidence supports a strong relationship between psychological stress and disease development.
These studies may be underestimating the impact of stressor exposure and the stress response on health, given that measuring these constructs has been challenging and limited. Recent work in the stress field has identified important aspects of psychological stress to capture in order to fully test the role that psychological stress plays in predicting disease; these include capturing the specific type s of stressor exposure, a wide range of psychological, cognitive, behavioral, and physiological responses to the exposure, and contextual and individual-level factors that moderate the impact of the exposure and response.
In this article, we identified ways for researchers to improve the language specificity when describing stress measures and offered guidance on how to choose the appropriate stress measure. We encourage the adoption of more precise language when writing about stress in academic papers, more careful selection of stress measures, with a focus on validated measures when possible, and theoretically driven integration of mechanistic pathways linking stress to health outcomes.
The ultimate goal of having sophisticated research on the relationship between stress, health, and well-being is to develop evidence-based ways to help people thrive in our stress-filled world.
Members of the Stress Measurement Network provided essential input on the thoughts presented here, and we thank them for their contribution. National Center for Biotechnology Information , U.
Journal List Health Psychol Open v. Health Psychol Open. Published online Jul 8. Author information Copyright and License information Disclaimer. Email: ude. This article has been cited by other articles in PMC. Abstract Despite the strong evidence linking psychological stress to disease risk, health researchers often fail to include psychological stress in models of health.
Keywords: health psychology, measurement, psychological distress, quantitative methods, stress. Introduction Epidemiological studies confirm that both experiencing a greater number of stressful events and reporting high perceived stress over long periods of time are associated with worse mental and physical health, and mortality Epel et al.
Measuring stressor exposures versus stress responses Stressor exposures can be measured with self-report questionnaires such as a life events checklist, assessed by an interviewer, or objectively determined based on proximity to an event e. Selecting stress measures Due to constraints on participant burden and other considerations, difficult choices about which type of stress to measure need to be made by researchers.
Stressor and stress response characteristics In addition to identifying stressor type s of interest, there are several key measurement considerations when choosing specific measures of stress to include in studies or analyzing existing stress measure data. Table 1. Types of stress by timescale. Type of stress Definition Relevance for health Chronic stress Chronic stressors are prolonged threatening or challenging circumstances that disrupt daily life and continue for an extended period of time minimum of one month.
People under the chronic stress are at greater risk of chronic illness, mortality, and accelerated biological aging Epel et al. Some life events can be positive e. Exposure to more stressful life events is linked with poorer mental health in addition to development and progression of cardiovascular disease, as well as mortality due to cardiovascular disease and cancer Chida et al. Experiencing a greater number of traumatic events across the life course is consistently associated with worse health and mortality Gawronski et al.
Daily hassles i. Greater emotional responses to these daily hassles are associated with worse mental and physical health Almeida, ; Charles et al.
Greater cardiovascular reactivity to acute stressors has been prospectively associated with increased risk of cardiovascular disease Brosschot et al. Open in a separate window. Types of stress response Responses to stressor exposures provide additional useful information beyond measuring stressor exposure alone. Additional characteristics of the stressor There are additional stressor exposure attributes that can be described and captured to thoroughly assess the exposure.
Characteristics of stress measurement Life stage during stressor exposure In addition to the timescale of the stressor, another important characteristic of stressor exposure is the developmental or life stage during which the stressor occurs.
Measurement assessment window The window of measurement is also essential to consider to avoid measurement error and improve specificity in hypotheses.
Summary of steps for selecting stress measures There are of course numerous considerations for selecting the appropriate stress measure for your study. Table 2. Summary of steps for choosing appropriate stress measures.
Steps for choosing an appropriate measure of psychological stress. Determine the type s of stress you intend to capture based on your research question and the uniqueness of your sample. Determine the timescale of the stressor exposure and how you will capture objective exposure. For the exposure variable, in particular, you may need to develop your own measure based on the uniqueness of your sample.
Identify which types of stress responses you are able to assess in your study design e. Determine the life stage in which the stressor occurs and choose a measure appropriate for that particular life stage. Identify additional characteristics of the stressor that are important to capture e. Look for well-validated scales that capture these aspects. It is common to use multiple scales to capture different aspects of the stress exposure and stress response, and the range of stress types that might be relevant for your sample.
Research on acute stress reactivity and physical health Decades of research have shown that heightened cardiovascular reactivity and delayed recovery to acute stressors are prospectively associated with increased cardiovascular disease risk Brosschot et al. Catecholamine and cortisol levels can be measured in the blood and urine.
Cortisol can also be detected in saliva and hair. Catecholamines can be measured in the blood, but this method has its flaws. Many people get apprehensive at the sight of the needle used to take the sample. This apprehension is enough to cause their catecholamine levels to skyrocket. For these reasons, an assay of catecholamines and their derivatives is mainly used for the diagnosis of pheochromocytomas and paragangliomas, two very rare types of tumours. Cortisol is easier to measure in the blood, but because its level varies greatly depending on the time of day, the time of collection is critical.
A cortisol assay is mainly used to assess adrenal gland dysfunction. The salivary rate remains the most widely used technique for measuring cortisol. Easy to obtain, even at home, samples can be repeated during the day. This makes it difficult to determine whether an individual is under intense stress.
Something one person might find extremely difficult, another would take in their stride, he says. But is measuring stress a good idea? The firms selling stress kits say they can help people see what impact their lifestyle is having on their health and make appropriate adjustments. Lynda Spain, a stress management consultant in Manchester, agrees that it's important to identify someone's stress level. Once she knows how stressed a client is she can take the next step and address it with cognitive behaviour therapy or other techniques.
But she doesn't use kits. And ask them if the mercury is at bursting point at the top or if they're halfway up and things are starting to get too much. Dr Porter says that trying to determine stress using quantitative measures is flawed. Saliva can be used to measure stress hormone levels, in clinical trials at least. And if you're stressed your pulse is likely to rise, as is your blood pressure. But it could be for lots of other reasons, too.
Doctors do not take these results particularly seriously in regard to stress, preferring to look at someone's wider circumstances, Dr Porter says. The studies need to be much bigger. Mian talks of benchmarking different stressors, looking at averages, age, sex, ethnic origins. It sounds like a big project, that is still largely unfinished. The Medistress test, Mian reminds me, has already been rolled out to professional football clubs.
A clinical rollout is on the horizon. Consumers are expected to navigate a gauntlet of products that claim to have potential medical benefits. Does the LCC test outperform salivary cortisol tests? Can it put a number on stress? It might, and it could. Does that make you feel stressed? You might want to get that measured. Chronic and acute stress in the body The story of stress starts in your brain. It involves the sympathetic nervous system, endocrine factors, blood biochemistry, cytokines, red blood cell hemodynamics… And the interesting thing about leukocytes is that they respond to all of those factors.
PMA stimulates white blood cells to produce oxygen free radical molecules, a process that is usually designed to fight off microbials.
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