Dissociation is a disruption of the usually integrated functions of consciousness, memory or perception of the environment. Many individuals with PTSD reported dissociative experiences.

In this case-control study, 130 of veterans with chronic PTSD and 130 matched individuals from normal population who had not involved in war were selected. First patients' demographic data were recorded, and then some suggested contributing factors were evaluated.Dissociative symptoms were evaluated via dissociative experience scale (DES). In this scale, score above 30 shows significant dissociation. Respondents were also evaluated by dissociative disorder interview schedule (DDIS) which is a semi-structural interview to discover presence of any dissociative disorder

The mean age±SD of veterans was 41.46±5.09 years. The mean score of DES in case group was 26.01±12.31 and was 9.58±7.23 in control group (F=1.171, P<0.0001). In case group, 74 (56.48%) received diagnosis of dissociative amnesia, 9 (6.87%) had diagnosis of dissociative fugue and 5(3.81%) had diagnosis of depersonalization disorder. Non of control group received additional diagnosis of dissociative disorder. Positive history of self cutting (c2 = 26.35, P<0.001) opioid dependence (c2 = 16.28, P<0.001) were more prevalent in case group.

Additional diagnosis of dissociative amnesia was the most prevalent of dissociative disorders in veterans. It is suggested that many complaint of veterans with chronic PTSD could be rather due to their dissociative symptoms rather than PTSD per se. Similar mechanism which could result in PTSD, in veterans, can prone them to dissociative disorders.