Researchers at the University of California Los Angeles have discovered a causal link between post-traumatic stress disorder and traumatic brain injuries. One group of rats was made to suffer a traumatic brain injury while another was left alone. Then, two days after the blow, both groups of rats were exposed to frightening stimuli. The unscathed rats responded appropriately to the stimuli, while the brain-injured rats severely overreacted. The findings suggest that one traumatic blow to the brain primes us for another, even if one is physical and the other is psychological.
