For the first time ever, researchers at the University of California, Los Angeles (UCLA) have found evidence of a causal link between traumatic brain injury (TBI) and post-traumatic stress disorder (PTSD).
An association between TBI and PTSD – the “signature wounds” of the Iraq and Afghanistan wars – has been observed for several years.
A 2008 study found that 44 percent of soldiers with a TBI were also diagnosed with PTSD. The connection between the two conditions seemed to some to be quite simple – the event that results in the TBI is also very frightening, leading to PTSD.
However, in light of the UCLA study, published in the journal Biological Psychology, some researchers now believe the link is deeper. The study indicates that the physical damage from the TBI alters the brain in a way that makes the victim more likely to develop PTSD.
The study was conducted in rats, where the researchers were able to separate physical from emotional traumas.
The rats were divided into two groups, and one group was subject to brain trauma. Then, 2 days after the brain trauma, all the rats underwent “fear conditioning.”
The researchers found that rats with the earlier TBI became more fearful than the control group of rats.
Michael Fanselow, senior author of the study, described that “it was as if the injury primed the brain for learning to be afraid.”
After examining the rats’ brains, the researchers found that the amygdala – which regulates the fear response in the brain – of the rats who had the TBI was in a more excitable state.
Their research indicates that when a person is exposed to a traumatic event, the brain is more capable of learning fear. It further suggests that if two soldiers were exposed to the same psychological trauma and one had previously suffered a TBI, the one who had suffered the TBI would be more likely to develop PTSD than the soldier with the uninjured brain.