Stress And The Cortisol Diurnal Profile — Is Only “High” Critical?
Objective: Results of recent studies on the diurnal profile of cortisol are presented. Their relevance concerning the child's brain and development are discussed.
Methods: Literature review. Keywords were (early) childhood and stress, toxic stress, traumatic stress, HPA-axis, cortisol diurnal profile and mental health.
Results: Traumatic stress can have significant effects on the child's brain that may eventually result in neurotoxic tissue injury (toxic stress). The psychobiological stress reaction is essentially regulated via the HPA-axis. It was generally believed that mainly a persistent elevation of cortisol levels constituted a marker for health risks. More recent studies indicate that chronic stress may have variable effects on cortisol levels depending on the time window analyzed. Afternoon levels seem to be elevated, whereas morning levels show a tendency to decline over time. This results in a blunted profile which is seen as a specific risk factor for acute subjective stress experience as well as mental health impairment (e.g. dissocial behavior, chronic fatigue, depression) in the long run.
Conclusion: Studies of childhood stress should include a focus on the dynamics of the cortisol diurnal profile. Lowered levels especially in the morning may point to the presence of traumatic stress. The resulting blunted profile indicates possible risk for wellbeing and health.
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