Foreword

The ability to assess the biomarker cortisol as an index of Hypothalamic Pituitary Adrenal (HPA) axis activity has provided enormous insights about the relations between psychosocial and physical environmental characteristics and the human stress response. Having a reliable and valid index of stress has also proven invaluable in examining the role of stress in mental and physical health. The ability to assess cortisol in saliva samples has opened up vast new areas of scientific exploration, particularly at the borders of social science with public health and medicine. The collection of salivary cortisol is a relatively unobtrusive procedure that can then be analyzed at low cost. It is remarkable that this book on salivary cortisol as a human stress biomarker is authored by a group of scientists from Scandinavia since, along with some prestigious scientists in Germany, much of the pioneering work on neuroendocrine biomarkers of stress has emanated from Sweden and Norway.

This volume arrives at an opportune moment with exponential growth in the use of salivary cortisol as a biomarker of stress coupled with remarkable interdisciplinary research on the borders of the social sciences and health. Thus we can ask two key questions about salivary cortisol and scientific research: What have we learned about the utility of salivary cortisol as a biomarker of stress? How should we use this tool to assess emerging scientific questions? Reading this book provides in depth answers to these questions.

This book provides a balanced, careful, and thorough review of literally hundreds of studies relating salivary cortisol indices to sociodemographic background characteristics of individuals such as socioeconomic status and gender, psychosocial working conditions (e.g., job control), perceived stress, and psychological resources such as social support. Studies of associations between salivary cortisol and biomarkers of cardiovascular and immune function as well as sleep processes are reviewed along with work on the relations between salivary cortisol and major health outcomes (e.g. cardiovascular disease, breast cancer) as well as mental health (e.g., depression). The authors identified all potentially relevant articles then applied systematic conceptual and methodological inclusion criteria to filter out irrelevant or sloppily conducted studies. They then systematically analyzed the remaining studies, tabling results in a manner that is easy to read and understand. Each table is organized by methods of saliva collection according to variables of interest (e.g., sociodemographic background, disease outcomes). The results of hundreds of studies are then discussed within each topic area taking into account the patterns of findings and implications for measurement and theory. As the reader will be able to see herein, the quality of data and the clarity of conclusions about salivary cortisol as a stress biomarker vary considerably because of measurement protocols, statistical and methodological controls, and important conceptual issues having to do with static versus dynamic measures and inter versus intra person comparisons.

The authors have done all of us who are interested in the interplay among environment, personal background, stress, and disease, a marvelous favor. They have extensively and accurately reviewed what we know about salivary cortisol as an index of human stress. The authors have provided direction as well for how future research on salivary cortisol as a biomarker of stress should proceed.