PTSD Can Develop Even Without Memory of the Trauma

Reports new study in Biological Psychiatry

Philadelphia, PA, August 14, 2014

There are many forms of memory and only some of these maybe critical for the development of posttraumatic stress disorder (PTSD),reports a new study by researchers at the University at Albany and theUniversity of California Los Angeles. Their findings, published in the currentissue of Biological Psychiatry,suggest that even with no explicit memory of an early childhood trauma,symptoms of PTSD can still develop in adulthood.

There are case reports of people who have experiencedterrible life events that resulted in brain damage, some of whom developedsyndromes similar to PTSD even though they had no recollection of the eventitself.

These reports suggest that explicit memory may not be anabsolute requirement for PTSD, whereas other forms of learning, such as fearconditioning, may be required.

Explicit memory is the type of memory that can bevoluntarily recalled from prior experience and articulated.

To test this hypothesis, Dr. Andrew Poulos and hiscolleagues conducted a study designed to answer a basic question: If traumaticearly life memories are lost, what persists of this experience?

In the laboratory, the researchers exposed juvenilerodents to a single session of unpredictable stress. Later, as adults, theytested the animals for their memory of the event and also measured their fearresponse.

"We found that our rodents, which failed to remember theenvironment in which they were traumatized, showed a persistent increase inanxiety related behavior and increased learning of new fear situations. Theseheightened levels of fear and anxiety corresponded with drastic changes in thedaily rhythms of the circulating hormone corticosterone," said Poulos.

Corticosterone is a hormone that, in part, regulates thebody's stress response. Interestingly, within the amygdala, a brain regioncrucial for the learning of fear, levels of a receptor for corticosterone werealso increased.

Poulos added, "Future experiments in our laboratory willallow us to determine if this increase in glucocorticoid receptors within theamygdala and/or aberrant hormone levels sets up the organism for increased fearand anxiety."

All together, these findings indicate that notremembering a traumatic event does not preclude an organism from experiencingsome of the negative consequences of trauma, such as anxiety and heightenedfear.

"These data highlight the importance of the many ways inwhich the brain processes traumatic experiences. Psychotherapy tends to focusheavily on the articulation of trauma memories. However, the current studyhighlights that these explicit memories may not represent all brain processesthat drive distress and disability," commented Dr. John Krystal, Editor of Biological Psychiatry. "In other wordsthere may be a mismatch between what people think and how they feel about theirtraumatic experiences. Thus, there may be role in treatment for measuring otherdimensions of response, such as physiologic arousal, through which some ofthese other forms of learning are expressed."

The article is "Amnesia for Early Life Stress Does NotPreclude the Adult Development of Posttraumatic Stress Disorder Symptoms inRats" by Andrew M. Poulos, Maxine Reger, Nehali Mehta, Irina Zhuravka, Sarah S.Sterlace, Camille Gannam, David A. Hovda, Christopher C. Giza, and Michael S.Fanselow (DOI: 10.1016/j.biopsych.2013.10.007). Thearticle appears in BiologicalPsychiatry, Volume 76, Issue 4 (August 15, 2014), published by Elsevier.


Notes for editors
Full text of the article is available to credentialedjournalists upon request; contact Rhiannon Bugno at +1 214 648 0880 or wishing to interview the authors may contact Dr. Andrew Poulos at+1 518 591 8886 or

Theauthors' affiliations, and disclosures of financial and conflicts of interestsare available in the article.

JohnH. Krystal, M.D., is Chairman of the Department of Psychiatry at the YaleUniversity School of Medicine, Chief of Psychiatry at Yale-New Haven Hospital,and a research psychiatrist at the VA Connecticut Healthcare System. Hisdisclosures of financial and conflicts of interests are available here.

AboutBiological Psychiatry
Biological Psychiatry is the official journal ofthe Society ofBiological Psychiatry,whose purpose is to promote excellence in scientific research and education infields that investigate the nature, causes, mechanisms and treatments of disordersof thought, emotion, or behavior. In accord with this mission, thispeer-reviewed, rapid-publication, international journal publishes both basicand clinical contributions from all disciplines and research areas relevant tothe pathophysiology and treatment of major psychiatric disorders.

Thejournal publishes novel results of original research which represent animportant new lead or significant impact on the field, particularly thoseaddressing genetic and environmental risk factors, neural circuitry andneurochemistry, and important new therapeutic approaches. Reviews andcommentaries that focus on topics of current research and interest are alsoencouraged.

BiologicalPsychiatryis one of the most selective and highly cited journals in the field ofpsychiatric neuroscience. It is ranked5th out of 135 Psychiatry titles and 14th out of 251Neurosciences titles in the Journal Citations Reports® published by ThomsonReuters. The 2013 Impact Factor score for Biological Psychiatry is9.472.

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