Every individual is unique. That may sound platitudinous and even useless. It does, however, get to the point of the question why some experience post-traumatic stress disorder (PTSD) while others do not despite shared or similar experiences like combat, natural disasters, personal tragedies, and so on. Every person is different from every other person, and that begins, first and foremost, in the brain. People process information differently and respond to stress and adversity differently. There are individuals who can experience combat or the stress associated with policing areas with high rates of violent crime and endemic poverty and not be emotionally affected. There are others, however, who are deeply affected by the same experiences to the point where they suffer emotionally and physically, be it with depression, headaches, disorientation, or anti-social tendencies.
The human brain is extraordinarily complex. Through advanced imaging technologies, though, researchers are learning more and more about how the brain responds to stress or trauma. Such research has shown that exposure, especially prolonged exposure, to traumatic events stimulates activity in the frontal lobe of the brain. It has also been determined that stress and trauma throws off the balance between the left and right hemispheres of the brain, the former responsible for logic and rationality and the latter for emotional responses. Under certain circumstances, and in certain individuals, changes to the brain that result from protracted or repeated trauma do not revert to their normal functioning; in effect, they stay stuck in a condition of heightened response. Because every person, and every brain, is unique, some are able to withstand the long-term effects of traumatic experiences “better” than others.
Some people are simply “wired” to respond to protracted periods of stress or trauma differently than others. There is no way to determine how each individual will endure such circumstances.