Early neglect and abuse predict diurnal cortisol patterns in adults A study of international adoptees

Neglect and abuse early in life have been associated with increased and decreased cortisol levels, and also with an altered diurnal cortisol slope. In the present study, we investigated the long-term relationship between early maltreatment - at different levels of severity - and basal cortisol secretion in adults adopted as children. A sample of international adoptees was followed from childhood to adulthood. In childhood, adoptive parents had provided information about neglect and abuse prior to adoption. As adults, adoptees collected saliva samples four times a day. The relationship between early maltreatment and cortisol secretion was examined, primarily with multilevel analyses in 623 adoptees. Morning cortisol levels were lower in adoptees whose adoptive parents had reported severe neglect or abuse than in non-neglected or non-abused participants (respective estimates (standard errors (SEs)) and p-values: -0.33 (0.090), p=0.0002 and -0.63 (0.20), p=0.002). Relative to non-neglected adoptees, those who had allegedly experienced severe neglect also had a flatter diurnal slope (estimate (SE) and p-value: 0.028 (0.0088), p=0.002). In contrast, relative to non-abused participants, adoptees whose reported abuse was moderately severe had high cortisol levels and a steeper cortisol diurnal slope (respective estimates (SEs) and p-values: 0.29 (0.13), p=0.003 and -0.039 (0.012), p=0.01). Thus, early neglect and abuse appear to have associations with cortisol levels and the diurnal slope, even when children are raised in another environment after their early maltreatment. Our study suggests that the severity of the early maltreatment may be related to the basal cortisol pattern.