of the HPA axis after children’s exposure to severe stress. The persistence of HPA dysregulation is not fully known, yet indications are that HPA dysregulation can last up to at least 5 years (De Bellis et al., 1994a; Goenjian et al., 1996; Putnam and Trickett, 1997). While findings are not always consistent and studies are difficult to perform, there is an expanding literature on children, adults with past childhood abuse, and on animal models (for review, see Heim and Nemeroff, 2001).
Altered activity of the HPA axis in children has been found in several studies focusing on cortisol and catecholamine levels. Studies of traumatized children with depression found lower salivary cortisol in the morning and a rise, rather than an expected reduction, in cortisol by evening (Hart et al., 1996; Kaufman, 1991). Elevations in urinary norepinephrine were found in neglected children with depression (Queiroz et al., 1991). A pilot study of sexually abused girls found elevated 24-hour catecholamine excretion (De Bellis et al., 1994b). A larger study of maltreated children with PTSD, mostly from sexual abuse, were found to have elevated levels of 24-hour urinary free cortisol, dopamine, and norepinephrine (De Bellis et al., 1999a). The degree of elevation was correlated with duration of the trauma and with severity of symptoms. Elevated cortisol and catecholamine levels are also found in adult women who were sexually abused as children (Lemieux and Coe, 1995). On the other hand, cortisol is lowered in adults with PTSD from combat or Holocaust exposure (Yehuda, 2000).
There are other indications of HPA dysregulation. One finding was increased ACTH response to CRF challenge in depressed children undergoing current abuse (Kaufman et al., 1997). The opposite had been found in children with past trauma studied several years after the abuse had been disclosed (De Bellis et al., 1994a). The difference may be from individual variability or from short-term effects versus long-term adaptations of the HPA axis. Lastly, dysfunctions of the serotonin system, which has interactions with the HPA axis, have been found in abused children (Kaufman et al., 1998). For discussion of the association between HPA axis and serotonergic system functioning and suicide, see Chapter 4.
Significant alterations in the anatomy and physiology of the developing brain are proposed to result from childhood trauma. Some of the observed changes in brain development may be produced by chronically elevated catecholamine and cortisol levels, possibly through their effects on neuron metabolism or death, neurogenesis or migration patterns, and delays in myelination (reviewed by De Bellis, 2001).