Post-traumatic stress disorder (PTSD) is a mental health condition characterized by a damaging reaction to exposure to traumatic events that pose (or seem to pose) a serious threat to life or well-being. Doctors and researchers are well aware that only some of the people exposed to highly traumatic circumstances will develop this condition. In a study published in 2014 in the Journal of Aggression, Maltreatment & Trauma, a team of American researchers explored the underlying reasons why some people develop PTSD in the aftermath of trauma while others do not. Emotional Trauma Psychologists and psychiatrists use the term trauma to describe a singular event or ongoing situation that overwhelms the natural human capacity to adjust to changing circumstances and maintain a sense of mental\/emotional equilibrium. As a rule, the types of events and situations responsible for overriding humans\u2019 coping capacity involve an actual threat to the life of the affected individual or a perception on the part of the individual that their life is at stake. Specific well-recognized sources of emotional trauma include rape and other forms of sexual assault, physical assaults, child abuse, participation in combat, exposure to an active combat zone, exposure to a natural disaster, involvement in a major accident and the development of serious forms of illness. Short-term reactions to emotional trauma commonly include an acute stress reaction known informally as shock, as well as some degree of denial about the reality of transpired events. If a person is seriously or severely affected by these or other symptoms within 30 days of the original trauma exposure, they may qualify for a diagnosis of a condition called acute stress disorder (ASD). Doctors consider making a diagnosis of PTSD in people who continue to experience a damaging reaction to traumatic events\/situations after a period of 30 days, as well in people who only start showing impairing symptoms of a traumatic stress reaction 30 days or more after an originating event or situation. How Many People Develop PTSD? The National Center for PTSD, a branch of the U.S. Department of Veterans Affairs, tracks the number of people in the U.S. who develop post-traumatic stress disorder in the aftermath of trauma exposure. Figures released by this institution in 2013 indicate that roughly 61 percent of all American men will be exposed to a highly traumatic event or situation at some point in their lifetimes; approximately 8 percent of these men will eventually meet the criteria for a PTSD diagnosis. Roughly 51 percent of all American women will be exposed to a highly traumatic event at some point in their lives; approximately 20 percent of these women will develop PTSD. Why Does PTSD Affect Certain People? In the study published in the Journal of Aggression, Maltreatment & Trauma, researchers from Winthrop University, Eastern Michigan University and Summa Health System used a project involving 195 college students to explore the underlying reasons why some people exposed to highly traumatic events\/situations develop PTSD, while others do not. All of these students (aged 18 to 42) took a series of tests that probed their personal history of trauma exposure, asked hypothetical questions about possible reactions to traumatic events\/situations and assessed the potential presence of PTSD symptoms. The researchers specifically wanted to know if the study participants\u2019 reactions to questions about actual events\/situations predicted the likelihood of developing PTSD. They pursued this goal by asking the participants if their trauma exposure was the result of their own actions or the actions of others, if their trauma exposure stemmed from shifting or ongoing circumstances and if their trauma exposure stemmed from a fairly isolated situation or from a more encompassing group of factors. The researchers also asked the participants to make the same judgments regarding a range of hypothetical traumatic situations\/events. After reviewing their data, the researchers found that roughly 12 to 16 percent of the study participants had symptoms that would likely qualify them for an official PTSD diagnosis. They concluded that the strongest predictor of developing these symptoms is the way in which a trauma survivor interprets the causes of trauma exposure. Specifically, the researchers found that people who attribute their trauma exposure to a wider variety of personal and societal influences have increased chances of feeling helpless or hopeless in the aftermath of trauma and therefore have the highest chances of developing relatively severe PTSD symptoms. The symptoms most likely to occur among such individuals are avoidance of reminders of traumatic events\/situations and a numbing of normal emotional responsiveness.