Fear Beyond Memory

In dealing with post-traumatic stress disorder (PTSD), psychotherapy traditionally tends to heavily focus  on the articulation of the patient’s memory of traumatic experiences. A study  led by University at Albany psychologist and neuroscientist Andrew M. Poulos,  however, posits that the brain processes other forms of memory, beyond explicit  recollection, that may be the drivers of distress and disability.

Hear More from Quilong MinThe findings of principal investigator Poulos and colleagues from UCLA, published in the August 2014 issue of Biological Psychiatry and funded by the National Institutes of Health, suggest that even with no explicit memory of an early childhood trauma, symptoms of PTSD, such as anxiety and heightened fear, can develop in adulthood.

Poulos and fellow researchers examined fear conditioning through early life trauma by exposing juvenile rodents to a single session of unpredictable stress. When the rodents became adults, the researchers tested the animals for their memory of the event and also measured their fear response.

“We found that our rodents, which failed to remember the environment in which they were traumatized, showed a persistent increase in anxiety-related behavior and increased learning of new fear situations,” said Poulos. “These heightened levels of fear and anxiety corresponded with drastic changes in the daily rhythms of the circulating hormone corticosterone.”

Corticosterone, in part, regulates the body’s stress response. The experiments by Poulos and the UCLA researchers found that within the amygdala, a brain region crucial for the learning of fear, levels of a receptor for corticosterone were also increased.

“Future experiments in our laboratory will allow us to determine if this increase in glucocorticoid receptors within the amygdala and/or aberrant hormone levels sets up the organism for increased fear and anxiety,” said Poulos.

Biological Psychiatry editor John Krystal believes the study may indicate a role in treatment for measuring other dimensions of response, such as physiological arousal, through which other forms of the brain’s processing of traumatic experiences are expressed.