ANN ARBOR—Contrary to conventional wisdom, it might be most effective to delay intervention for victims of severe psychological traumas such as military combat or rape, according to new research at the University of Michigan.

The research, detailed in the Proceedings of the National Academy of Sciences (PNAS) this week, suggests that the effectiveness of an early intervention may depend on the level of acute stress. Early intervention in some cases could make the situation worse, the research says.

Extremely taumatic events can trigger crippling and persistent psychological reactions, including post-traumatic stress disorder (PTSD). The U-M research found that delaying intervention by 24 hours may make it easier to reverse the impact of the trauma.

Stephen Maren, a U-M psychology professor and associate director of the interdepartmental Neuroscience Program, studies how the brain reacts to emotions such as fear. Maren and U-M colleague Chun-Hui Chang compared two strategies” early and delayed interventions” for reducing a post-traumatic stress-like condition in rats.

The rats were first submitted to fear conditioning that involved presenting the animals with an auditory tone followed by the delivery of a foot-shock. The animals were then exposed to ” extinction trials” ” the tone without the foot-shock” either 15 minutes later or after 24-hours, in the case of the delayed intervention.

The purpose of the extinction training is to reverse or dull the memory of the initial trauma by uncoupling the tone from the foot-shock. Maren and Chang discovered that contrary to current conventional wisdom, the delayed intervention was more effective at suppressing the fearful memory

More than one-third of Americans suffer from an anxiety disorder at least once in their lifetime, but research is finding some proven ways to overcome such conditions, Maren said. Such fear reactions are designed to help us survive, but researchers are finding ways to help people cope.

The solution to overcoming fears, anxieties or phobias, Maren says, seems to be repeated exposure to the fear-related stimuli in safe conditions until people realize the perceived threats are not dangerous. Although it is clearly important to manage acute stress after a traumatic event, the current work suggests that therapeutic interventions for fear memories might be most effective days or possibly weeks after a traumatic event.

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