ATLANTA – A single traumatic event when children are 8–12 years old might trigger neurophysiologic changes that predispose them to long-lasting vulnerability for a heightened startle response.
Dr. Robert S. Pynoos, director of outpatient trauma psychiatry at the University of California, Los Angeles, said he and his colleagues assessed 17 children who met the full criteria for posttraumatic stress disorder (PTSD), 8 with partial PTSD, and 16 age- and gender-matched controls without PTSD. They measured the startle magnitude to a binaural acoustic startle.
The groups with PTSD had experienced a single, circumscribed traumatic event in the past 14 months, Dr. Pynoos reported at the annual meeting of the International Society for Trauma Stress Studies. The traumatic events were serious–one child had been kidnapped and witnessed the rape of his or her mother.
Elapsed time since the event, IQ, ethnicity, and socioeconomic status had no significant effect on the findings. “Children with trauma but partial PTSD still [showed a] significant difference” he said, noting they could reduce their startle response by only 40%, compared with 50%-60% in controls. Children with full criteria PTSD were more severely impaired in their response, able to modulate it by only 30%, which is similar to a 3-year-old.
Humans and animals use the same four-neuron connection in startle; in humans, however, the amygdala can alter the response or the cortical system can inhibit it through many different mechanisms, said Dr. Pynoos. “All this is involved in modifying the startle reaction at the same point–before motor action. It is important to educate parents they cannot teach their children out of their responses. And we need to know [patients] may carry vulnerability into the future based on neurobiologic changes during this critical period.”
Dr. Pynoos said that he had no relevant disclosures.