People with PTSD may relive their traumatic experiences because they overgeneralize their memories, according to recent findings from a group of American researchers. The unwanted reliving or re-experiencing of highly traumatic experiences is one of the four core symptoms of post-traumatic stress disorder (PTSD), a condition affecting a sizable number of American men and women. In a study published in December 2014 in the Journal of Traumatic Stress, researchers from four U.S. institutions sought to determine the role that overgeneralization of memory plays in triggering the reliving of trauma in people with PTSD. The researchers concluded that memory overgeneralization may be the underlying cause of this symptom. PTSD and the Reliving of Trauma As its name implies, post-traumatic stress disorder appears in the aftermath of exposure to highly traumatic events or situations that overtax the human ability to cope with stress and maintain an ongoing sense of mental well-being. Specific sources of trauma most likely to trigger the onset of the disorder include combat exposure and sexual assault exposure. Additional known PTSD triggers include childhood exposure to sexual or physical abuse, natural disaster exposure, terrorism exposure, involvement in major accidents and the development of a life-threatening illness. In some cases, PTSD is an extension of a shorter-term diagnosable condition called acute stress disorder (ASD), which lasts up to a month after a traumatic event or situation. In other cases, post-traumatic stress disorder appears a month or more after trauma exposure in people who never had ASD. Some people with PTSD relive the memories of their traumatic experiences in great detail during waking hours; the accepted term for this waking intrusion of memory is a \u201cflashback.\u201d Other people relive their traumatic experiences in the form of nightmares. In either case, the memories are unwanted and significantly destabilize the well-being of affected individuals. Potential causes of PTSD-related flashbacks and nightmares include events or situations that serve as reminders of the trauma source and seemingly random thought processes that bring the individual back to a traumatic experience. Memory Generalization Essentially all human beings past the earliest stages of life have specific and general memories. Specific memories are relatively detailed recollections of events or situations that allow a person to develop a personalized sense of the past. On the other hand, general memories are much less detailed accounts of the past that give a person the flexibility to apply knowledge gained through prior experiences to new situations and events. Psychologists and psychiatrists know that any given individual can have an overly specific memory or an overly general memory. In effect, people with overly general memories introduce \u201cstatic\u201d into the memory process and increase their chances of incompletely or incorrectly applying past experiences to current circumstances. Memory Overgeneralization and PTSD In the study published in the Journal of Traumatic Stress, researchers from the Veterans Administration, Rutgers University\u2019s New Jersey School of Medicine, the Department of Veterans Affairs and Harvard Medical School used a project involving 114 veterans of military service to explore the role that memory overgeneralization plays in the reliving of traumatic experiences in people with PTSD. The researchers essentially wanted to know if the brain networks of individuals affected by the disorder are unusually prone to triggering recall of traumatic experiences when even highly vague potential reminders of those experiences arise in the mind. To this end, all of the study participants underwent detailed testing of their memory and learning patterns. In addition, each participant provided information on the specific nature of his or her PTSD symptoms. After analyzing the data from the memory testing and considering other potential intervening factors, the researchers concluded that the unwanted re-experiencing of traumatic events and situations is indeed linked to a tendency to overgeneralize memories and misapply those memories to current circumstances. The researchers also concluded that, for the typical person with PTSD, the frequency of flashbacks or nightmares is linked to the extent of memory overgeneralization. The study\u2019s authors note that people with PTSD don\u2019t appear to have other memory or learning problems capable of contributing to the likelihood of reliving their traumatic experiences. They believe that their findings help explain why individuals affected by the disorder develop flashbacks or nightmares; however, they also note that memory overgeneralization in a person with PTSD can also occur in a much wider range of ordinary, everyday circumstances.