Childhood maltreatment has been found to be strongly associated with major depressive disorder (MDD), particularly among females; however, it remains unclear why some individuals exposed to abuse or neglect subsequently experience MDD while others do not. Researchers have hypothesized that "alterations in corticotrophin-releasing hormone (CRH) mediate the development of MDD" and linked increased activation of the hypothalamic-pituitary-adrenal axis (HPA) to severe stress in early life. This study, part of a larger longitudinal investigation, explored whether "resting levels of cortisol, heart rate, and pattern of stress response to a psychosocial stressor differed" between female youth exposed to maltreatment (defined as physical, sexual, and emotional abuse and neglect) and a control group matched on age and postal code (p. 62).
Female youth (n = 67) aged 12 to 16 with no prior history of depression or cognitive impairment were recruited from three child protection agencies; a control group comprised of youth (n = 25) with no history of maltreatment was selected from a pre-existing database of youth willing to participate in research. Visited by a public health nurse, youth completed two self-report instruments measuring child maltreatment, had their heart rate (HR) monitored, and saliva samples taken. Psychiatric stress was assessed by a trained clinician using the Trier Social Stress Test (TSST), the Schedule for Affective Disorders and Schizophrenia for School-Aged Children. "The time prior to the TSST was conceptualized as a resting measure of cortisol, while the post-TSST period was considered cortisol reactivity" (p. 63).
Complex statistical analyses "examined differences between maltreated and control youth in resting and post-TSST levels of cortisol and HR" (p. 63). Both groups showed a similar decline in levels of cortisol during the resting period. Youth in the control group experienced an increase in cortisol levels following the TSST and a gradual flattening over time; maltreated youth exhibited a blunted cortisol response not associated with current systems of MDD. No differences were found in resting and reactivity levels of HR. The authors conclude the findings add to evidence linking chronic stress to "reduced physiological responsiveness to new stressors over time" (p. 66). Future research is necessary to clarify the clinical relevance of these results; however, the authors suggest blunted cortisol response may put maltreated youth at risk for impairment in both physical and emotional health.