Stress Biomarkers as an Objective Window on Experience

Abstract

Studies of stress are difficult because stress is often not clearly defined and can be seen as a stimulus, a response, or something in-between. Stress is usually measured through self-reports – such as hassles scales, perceived stress questionnaires, and life events scales – but there are sex, ethnic, socioeconomic, and cultural differences in how individuals do this reporting, and individuals may not be consciously aware of whether or to what degree they are stressed. Biological markers can provide an objective measure of stress, providing a means to make visible the invisible nature of the stress experience. However, these markers differ in the duration over which stress is measured, and they may be influenced by other conditions, such as endocrine disorders. Also, some measures are only valuable in laboratory settings, limiting those that can be used to understand stress levels in people’s daily lives. Investigators must insure that the measures used in their studies do not actually cause stress, and thus noninvasive measures are required. Studies using stress biomarkers have shown that culture change and modernization generally lead to an increase in mean stress levels. These studies also show that the stress experience is quite varied, with subtleties in how individuals and populations experience stress. The general stress response evolved as an adaptation to conditions quite different from those found today, and in many cases the response has become maladaptive, with prolonged high levels of stress, conceptualized as an enhanced allostatic load, leading to increased risk for development of chronic diseases.