Cortisol response to synacthen stimulation is attenuated following abusive head trauma.

Background: Child abuse and other early-life environmental stressors are known to affect the hypothalamic-pituitary-adrenal axis. We sought to compare synacthen-stimulated cortisol responses in children who suffered inflicted or accidental traumatic brain injury (TBI).

Methods: Children with a history of early-childhood TBI were recruited from the Starship Children's Hospital database (Auckland, New Zealand, 1992-2010). All underwent a low-dose ACTH(1-24) (synacthen 1 μg IV) test, and serum cortisol response was compared between inflicted (TBI(I) ) and accidental (TBI(A) ) groups.

Results: We assessed 64 children with TBI(I) and 134 with TBI(A) . Boys were more likely than girls to suffer accidental (P < 0·001), but not inflicted TBI. TBI(I) children displayed a 14% reduction in peak stimulated cortisol in comparison with the TBI(A) group (P < 0·001), as well as reduced cortisol responses at + 30 (P < 0·01) and + 60 min (P < 0·001). Importantly, these differences were not associated with severity of injury. The odds ratio of TBI(I) children having a mother who suffered domestic violence during pregnancy was 6·2 times that of the TBI(A) group (P < 0·001). However, reported domestic violence during pregnancy or placement of child in foster care did not appear to affect cortisol responses.

Conclusion: Synacthen-stimulated cortisol response is attenuated following inflicted TBI in early childhood. This may reflect chronic exposure to environmental stress as opposed to pituitary injury or early-life programming.