Neurotoxic Effects of Childhood Trauma
December 30, 2005
DeBellis (2004) defines maltreatment during childhood as neglect, physical, sexual and emotional abuse which constitutes a chronic and profound degree of stress. He pointed out that recent neuroimaging studies in adult PTSD and other anxiety disorders provide evidence for medial prefrontal and anterior cingulate dysfunction. Results from pediatric studies suggest that maltreated children have excessive cortisol secretion. DeBellis (2004) noted that elevated levels of catecholamines and cortisol may lead to adverse neural development through the loss of neurons, delays in myelination, abnormalities in developmentally appropriate pruning, or the inhibition of neurogenesis and decreases in the expression of brain-derived neurotrophic factor (BDNF).
In a review of the MRI studies on maltreated treated children, DeBellis (2004) noted “smaller intracranial and cerebral volumes, smaller total midsagittal area and middle and posterior regions of the corpus callosum, and larger ventricular volumes than in nonabused control subjects” (p.160). A positive correlation between intracranial volumes with age at onset of PTSD trauma suggested that stress is associated with disproportionately negative consequences if it occurs during early childhood. DeBellis hypothesized that childhood maltreatment has global adverse influences on brain development which may be cumulative. He observed in one of his research studies: “Symptoms of intrusive thoughts, avoidance, hyperarousal, and dissociation correlated positively with ventricular volume[ventriculomegaly associated with trauma], and negatively with intracranial volume and total corpus callosum and regional measures” (p.161).
In another research study of children and adolescents from his group, DeBellis noted: “Subjects with PTSD had smaller intracranial, cerebral and prefrontal cortex, prefrontal cortical white matter, and right temporal lobe volumes and areas of the corpus callosum and its subregions and larger frontal lobe CSF volumes [ventriculomegaly] than control subjects” (p.161). Neural volumes were positively correlated with age at onset of PTSD trauma and negatively correlated with duration of abuse. DeBellis suggested that PTSD in maltreated children may be regarded as a “complex, environmentally induced developmental disorder” (p.162). Magnetic resonance spectroscopy (MRS) has been used in studying the effects of trauma in maltreated children and adolescents. Levels of N-acetyl aspartate (NAA), a marker of neuronal integrity,in the anterior cingulate region of the medial prefrontal cortex, has been observed to be depressed in maltreated children and adolescents. This is also observed in persons diagnosed with schizophrenia. Parenthetically, studies of adult primates whose mothers were subjected to a variable foraging demand paradigm, i.e., uncertainty of food supply, during their early development also evidenced decreased NAA in their prefrontal cortex as well as dysregulation of their LHPA (limbic-hypothalmic-pituitary-adrenal) axis and increased expression of cortico-tropin-releasing hormone (CRH)-the latter being released during times of distress.
Brian Koehler PhD
New York University
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New York NY 10003
212.533.5687
brian_koehler@psychoanalysis.net
