Showing papers by "Angela Clow published in 2020"

Stress, the cortisol awakening response and cognitive function.

Abstract: There is evidence that stress-induced disruption of the circadian rhythm of cortisol secretion, has negative consequences for brain health. The cortisol awakening response (CAR) is the most prominent and dynamic aspect of this rhythm. It has complex regulatory mechanisms making it distinct from the rest of the cortisol circadian rhythm, and is frequently investigated as a biomarker of stress and potential intermediary between stress and impaired brain function. Despite this, the precise function of the CAR within the healthy cortisol circadian rhythm remains poorly understood. Cortisol is a powerful hormone known to influence cognition in multiple and complex ways. Studies of the CAR and cognitive function have used varied methodological approaches which have produced similarly varied findings. The present review considers the accumulating evidence linking stress, attenuation of the CAR and reduced cognitive function, and seeks to contextualize the many findings to study populations, cognitive measures, and CAR methodologies employed. Associations between the CAR and both memory and executive functions are discussed in relation to its potential role as a neuroendocrine time of day signal that synchronizes peripheral clocks throughout the brain to enable optimum function, and recommendations for future research are provided.

Salivary cortisol as a non-invasive window on the brain.

Abstract: The validation of accurate and meaningful assessment of cortisol in saliva samples has proved revolutionary in stress research. Its many advantages have expanded the scope of investigation from traditional laboratory and clinical settings to include multidisciplinary and community-based research. These developments have given rise to a wealth insight into the links between stress and health. Here we highlight the potential of salivary cortisol as both a product and mediator of brain function, instrumental in disturbing brain health. However, the subtleties of salivary cortisol as a measure can be underestimated, leading to misinterpretation of findings. These issues are explored, with a particular emphasis on necessary methodological rigor. Notwithstanding great promise, there is undeniably more to learn so we conclude by making recommendations for future research including use of salivary cortisol in the development of integrative predictive models of stress-related risk factors and resilience across the life course.

Salivary Bioscience, Human Stress and the Hypothalamic–Pituitary–Adrenal Axis

Abstract: Since validation in the late 1990s measurement of cortisol in saliva has revolutionised the study of human stress. Cortisol secretion is controlled by the brain and in addition to being a principal regulator of circadian rhythms, it is the body’s main stress hormone. The use of salivary measures has spawned an exponential growth in studies exploring individual differences in reactions to stress and consequent impact on health and circadian rhythms. Several key features have facilitated this work: saliva samples can be self-collected both within and outside of laboratory settings; stress-free repeated sampling enables examination of short-term changes in concentration. Researchers have utilised these advantages to measure relationships between stress and health and have explored an astonishingly wide array of research questions that have shone a torch on how the way we feel affects our physical and mental health and well-being. In this chapter, we explore the main approaches to using salivary cortisol in human stress research both within the laboratory and in the domestic setting. We highlight crucial methodological considerations when measuring basal diurnal cortisol patterns as well as stress reactivity. Key findings from this body of work will be summarised as well as exciting potential future directions discussed.