Delayed Treatment May Be Better for Trauma Victims
Study in rats show animals respond better when treatment is postponed 24 hours
THURSDAY, Nov. 9 (HealthDay News) -- Delayed treatment intervention might be more effective than early treatment for suppressing fearful memories after a traumatic event, according to the results of a study of rats published online Nov. 7 in the Proceedings of the National Academy of Sciences Early Edition.
Stephen Maren, Ph.D., and a colleague from the University of Michigan in Ann Arbor, conditioned rats to receive an electric shock to the foot immediately after an auditory tone. The rats were then subjected to "extinction trials" where the auditory tone was delivered without the footshock. Extinction trials were conducted either within 15 minutes of conditioning or 24 hours later.
Extinction trials conducted immediately after conditioning produced a short-term effect on fear suppression, but the response did not last into the next day. Instead, the rats continued to display freezing behavior in response to the tone. When extinction therapy was postponed until the day after conditioning, fear suppression lasted longer.
"These results reveal that the level of fear present at the time of intervention is a critical factor in the efficacy of extinction," the authors write. "Importantly, our work suggests that early intervention may not yield optimal outcomes in reducing post-traumatic stress, particularly after severe trauma."