Early cortisol awakening response as a biological risk marker in young children

Abstract

Background : Recent research suggests that atypical cortisol awakening response (CAR) is an outcome of negative factors, such as post traumatic stress disorder (PTSD) (Johnson et al., 2008) and insomnia (Backhaus et al., 2004), in adults. While a positive CAR is present in the vast majority of adults, less is known about the normal development of this response in children. Without a clear sense of typical emergence in early childhood, it is uncertain if risk factors can be standardly associated with the magnitude of CAR during development. Our study aims to expand current research on CAR to children under the age of 8 years. We aim to understand how CAR manifests in young children and how methodological, familial, and child-specific factors contribute to positive CAR (responders). Methods : Fifty-two children (54% female) and mothers participated, ranging in age from 1 to 8 years (M: 4.88, SD: 1.72). Mothers were asked to complete several questionnaires and were sent a “cortisol packet” with instructions to obtain child saliva samples when they awoke (T1) and 45 minutes later (T2) across 2 days. “Responders” were identified as children whose cortisol levels increased from T1 to T2. Results : No difference in responder group by child age was found in this sample. It may suggest a step-like model, such that emergence of positive CAR would begin in infancy (38%: Saridjan, 2010) and that rates may start to increase only around age 10 (60%: Freitag, 2009) until they stabilize in adulthood (75%: Wust, 2000). In contrast to previous literature, methodological variables, such as daily routine and time between samples (Griefahn & Robens, 2011), were not significantly associated with responder status. However, results were consistent with Saridjan and colleagues (2010), demonstrating that lower family income was associated with greater likelihood of being a responder. Maternal psychopathology had no effect on child CAR status. Interestingly, for child-specific factors, internalizing and externalizing scores had the opposite effect such that, for every increase in externalizing score the risk of being in the responder group increased by 13.5%; however, for every increase in internalizing score, the risk of being a responder decreased by 10%. Conclusions : Future research should aim to understand the effects of pure internalizing and externalizing versus comorbidity on cortisol in larger samples.

Keywords

• preschoolers
• cortisol awakening response
• stress
• risk factors
• internalizing problems
• externalizing problems