People react differently to stressful circumstances depending on their unique coping mechanisms and accessible support networks. According to studies on how trauma affects different groups, the vast majority of people who are not directly and personally impacted by a horrific catastrophe don't suffer any long-term effects. The majority of people who experience or participate in tragic occurrences are able, over time, to find a way to go on with their lives with minimal change in their ability to love, trust in, and have hope for the future.
People who, out of need, emotionally shut out unpleasant occurrences both during and after the incident might develop post-traumatic stress disorder (PTSD). This enables the experience to dictate how people plan their lives and often leads to their seeing upcoming stressful life occurrences in the context of their earlier trauma. Such a focus on the past progressively robs their life of purpose and enjoyment.
PTSD was first described and has symptoms as early as Ancient Greece. However, it wasn't until 1980 that the Diagnostic and Statistical Manual (DSM) of the American Psychiatric Association (APA) included the set of symptoms recognized as a mental disease as a result of the suffering of Vietnam War soldiers.
The effect of trauma varies in intensity depending on the victim's age, stage of development, and the kind of trauma experienced, such as whether it was relational and brought on by a close relative, an outsider, a war or natural catastrophe, etc.