An Investigation of the Comorbidity and Relationship Between Post-Traumatic Stress Disorder, Personality Disorders and Axis-I Disorders in a Psychiatric Outpatient Population of Active Duty Armed Forces Personnel.

Main Objectives: To investigate the types of traumatic events that lead to post-traumatic stress disorder (PTSD) and whether personality disorder (PD) acts as a possible exacerbating factor in the experience of PTSD and other Axis-I disorders from the Diagnostic and Statistical Manual for Mental Disorders (American Psychiatric Association; APA, DSM-IV, 1994), and also to establish differences in the prevalence of particular PD s among participants with PTSD and those without PTSD. Design and Setting: The study employed a retrospective, comparative between and within groups design. Participants were recruited from Army and RAF military outpatient psychiatric settings (Department of Community Psychiatry; DCP) around the UK. Participants: Participants were a U K sample population of active duty armed forces personnel presenting for treatment at a DCP. Of the sample population (n = 46), 21 met criteria for PTSD on the Posttraumatic stress Diagnostic Scale (PDS; Foa, 1995) and were assigned to the experimental PTSD group. As the remaining 25 participants did not meet PTSD diagnostic, they formed the N on-PTSD group. All female personnel were excluded from the study, as were males presenting with an organic or psychotic disorder. Main outcome measures: Each participant completed the PDS and the Millon Clinical Multiaxial Inventory-Ill (MCMI-III; MQlon, 1994) and was interviewed by the Trainee Clinical Psychologist using the Structured Clinical Interview for DSM-IV Axis II disorders (SCID-II; First, Gibbon, Spitzer, Williams & Benjamin, 1997). Results: No significant differences were found between the two groups regarding the presence of PD or types of PDs identified. Participants with PTSD were found to have more Cluster A PDs and participants in the Non-PTSD group had more Cluster B PDs. In this study, the presence of PD made no difference to PTSD symptom severity. Alcohol dependence was not observed to be a significant comorbid Axis-I disorder in either group. The comorbid PTSD-PD group had higher MCMI-III mean BR scores for anxiety, dysthymia, major depression, somatoform and delusional disorder compared with the other groups. No difference was observed between the groups on the number or types of traumas experienced. Participants who just failed to meet PTSD diagnostic criteria may have influenced the results, although this finding was not statistically significant Conclusion: PTSD may be underdiagnosed when trauma is not the obvious presenting problem; therefore the disorder should be screened for during routine psychiatric interviews. Relying on cut-off scores on PTSD diagnostic tools may result in those individuals with subthreshold levels of PTSD being misdiagnosed. Diagnostic measures should not be used in isolation of other clarifying information.