Conclusions

This chapter has reviewed the neurobiology of stress and memory as it applies to traumatized children and questions related to delayed recall of childhood abuse. Studies of the effects of memory have shown that stressful events are remembered differently than normal events. For instance, evidence from "flashbulb" memory studies showed that emotional events are remembered better than neutral events. Other studies showed that the central features of emotional events are remembered better than peripheral details. Studies in normal children have shown that stressful memories in general are remembered accurately and are typically more resistant to suggestion.

Results from studies of abuse victims related to their ability to remember their abuse events have been varied. Due to the complex nature of abuse, underreporting, and the difficulties of verification, research in this area has been very difficult.

Studies have shown that memory is subject to distortion. However, implausible memories are more difficult to "implant" than plausible memories, making it less likely that individuals can have memories of traumatic memories "implanted." On the other hand, abuse-related patients with mental disorders have greater memory impairment, making it more likely that they may have "source memory" errors. Consistent with this are studies showing that abused PTSD patients are more susceptible to suggestion on the Deese/Roediger-McDermott paradigm. For these reasons, therapists should proceed with caution in discussions of early abuse and not provide suggestions about abuse that the patient is not aware of.

Neurobiological studies have implications for the recall of abuse. Patients with abuse-related mental disorders have a wide range of memory impairments. At its most extreme, patients with early abuse and DID have a complete breakdown of autobiographical memory, making the accurate recall of personal life experiences more difficult. Patients with abuse-related mental disorders also have smaller hippocampal volume, which we hypothesize is stress related. Altered hippocampal function can be associated with an impairment of memory recall, or the accurate integration of individual elements of memory.

Abuse-related PTSD is also associated with increased amygdala function and decreased function of the medial prefrontal cortex/anterior cingulate. Increased amygdala function is associated with enhanced fear responses, while a failure of medial prefrontal function is associated with a failure of extinction, or inability to turn off the fear response. Deficits in medial pre-frontal function are also seen in women with early abuse and BPD. Given the enhanced brain responsiveness to reminders of the trauma, it is anticipated that patients with early-abuse-related psychopathology will avoid reminders of the abuse, which may lead to the development of amnesia.

Changes in stress-responsive hormonal systems may also have an effect on memory in patients with abuse-related mental disorders. Traumatic memories can be both enhanced and impaired depending on release of stress hormones such as cortisol and norepinephrine, as well as the effects of stress on brain areas involved in memory and emotion such as the hippocampus, amygdala, and prefrontal cortex.

Understanding how stress affects memory and the brain will have important implications for the treatment of traumatized children throughout their lives. This area also has implications for public health and for promoting the health of children.

Future studies should examine normal and stress-related memory in children and adults with early childhood abuse-related mental disorders.

Other studies should continue to assess brain circuits and systems involved in memory and the stress response and the effects of treatments on these brain systems. These studies need to expand beyond brain function to areas such as neuroreceptors and neurosignalling pathways. Finally, research should shift from exploring the consequences of abuse to investigating novel approaches toward prevention.

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