Uncontrollability and unpredictability in post-traumatic stress disorder: an animal model.

The disturbances observed in animals subjected to unpredictable and uncontrollable aversive events resemble post-traumatic stress disorder (PTSD) symptoms and thus may constitute an animal model of this disorder. It is argued that the similarity between animals' symptoms and those of trauma victims may reflect common etiological factors. Relevant experiments in which animals exhibit generalized fear and arousal, discrete fear of a conditioned stimulus (CS), analgesia, and avoidance are reviewed with the view that these manifestations may be analogous to the PTSD symptom clusters of persistent arousal, reexperiencing, numbing, and avoidance, respectively. Finally, animal paradigms are suggested to test the validity of the model and specific hypotheses are derived from the animal literature regarding trauma variables that are predictive of particular PTSD symptom clusters.