Ambulatory measurement of cortisol: Where do we stand, and which way to follow?

Abstract

Accumulating evidence supports the harmful effects of stress on health, including the development and progress of psychopathology (e.g. anxiety disorders), metabolic disorders (e.g. diabetes type II), inflammatory disturbances, and cardiovascular disease. These harmful effects are often expressed as disturbances in cortisol levels, patterns, or responses. Unfortunately, at present, cortisol assessment is only performed in the laboratory. This hinders rapid quantification, let alone being determined by individuals themselves, with self-testing devices or sensors. More accurate and timely detection of cortisol may have important implications for the prevention, diagnosis, and treatment of stress-related disorders as well as for those suffering from adrenal insufficiencies. The present review provides an overview of the most promising and challenging technologies for cortisol measurement. An important first conclusion might be that almost all reviewed technologies were at the proof-of-concept stage, meaning it was premature to interpret the findings in light of regulatory requirements for in vitro diagnostics. Nevertheless, several promising proto-types, including electrochemical sensors with wearable potential, were found and are consequently discussed. Overall the findings suggest that with significant additional investments and research efforts in the coming years, accurate, rapid, and repeated cortisol assessment in everyday life can become reality.