Memory for traumatic experiences in early childhood

In animals, exposure to severe stress can damage the hippocampus. Recent human studies show smaller hippocampal volume in individuals with the stress-related psychiatric condition posttraumatic stress disorder (PTSD). Does this represent the neurotoxic effect of trauma, or is smaller hippocampal volume a pre-existing condition that renders the brain more vulnerable to the development of pathological stress responses? In monozygotic twins discordant for trauma exposure, we found evidence that smaller hippocampi indeed constitute a risk factor for the development of stress-related psychopathology. Disorder severity in PTSD patients who were exposed to trauma was negatively correlated with the hippocampal volume of both the patients and the patients' trauma-unexposed identical co-twin. Furthermore, severe PTSD twin pairs-both the trauma-exposed and unexposed members-had significantly smaller hippocampi than non-PTSD pairs.

A cognitive theory of posttraumatic stress disorder (PTSD) is proposed that assumes traumas experienced after early childhood give rise to 2 sorts of memory, 1 verbally accessible and 1 automatically accessible through appropriate situational cues. These different types of memory are used to explain the complex phenomenology of PTSD, including the experiences of reliving the traumatic event and of emotionally processing the trauma. The theory considers 3 possible outcomes of the emotional processing of trauma, successful completion, chronic processing, and premature inhibition of processing We discuss the implications of the theory for research design, clinical practice, and resolving contradictions in the empirical data.