Researchers at the University of South Florida and James A. Haley Veterans' Hospital have shown for the first time that a remote, fear-provoking memory disrupts the ability of rats to remember new information — a symptom common in people with post-traumatic stress disorder (PTSD). The animal model they developed may eventually lead to improved drug treatments for people with anxiety disorders such as PTSD.
James Woodson, PhD, will present the study results today at the American Society for Pharmacology & Experimental Therapeutics session at the Experimental Biology 2003 meeting in San Diego, CA. Dr. Woodson, a USF postdoctoral fellow, and David Diamond, PhD, a USF associate professor of psychology, pharmacology and therapeutics, study long-term intrusive emotional memories in rats to better understand the neurobiology of this critical component of PTSD. Both are also research scientists at the James A. Haley VA Hospital in Tampa.
"Intrusive memories are one of the cruelest aspects of post-traumatic stress disorder because people live in constant fear of these memories resurfacing," Dr. Diamond said. "Subtle reminders of their trauma can trigger panic attacks in people with PTSD many years after the original experience occurred."
The investigators demonstrated that when young adult rats have a fear-provoking experience they remember that experience for at least six months — one quarter of their lifespan. Furthermore, when the rats later in life were given a reminder of the fear-provoking experience, they exhibited behavioral symptoms similar to those in people with PTSD. For example, they avoided cues associated with the original experience and their long-term emotional memories impaired their ability to remember new information.
Using the animal model, Dr. Diamond and Dr. Woodson are continuing to investigate how the hippocampus, as well as other brain regions involved in emotional trauma, such as the amygdala, are affected by intrusive memories. The researchers also plan to test novel medications that may stop intrusive memories from disrupting behavior later in life.
Their research is supported by a five-year grant from the Veterans Adminstration.