Comorbid intermittent explosive disorder and posttraumatic stress disorder: Clinical correlates and relationship to suicidal behavior.

OBJECTIVE: Posttraumatic stress disorder (PTSD) is associated with both aggressive and suicidal behavior. Recent research suggests that the diagnosis of intermittent explosive disorder (IED), an impulse-control disorder characterized by repeated impulsive aggressive behavior, may help to identify individuals at risk for attempting suicide. Given the relationship between anger and PTSD, there is likely to be an increased prevalence of IED among individuals with PTSD; however, little is known about the overlap in these two disorders, including how individuals with comorbid IED and PTSD may differ from those with either disorder alone. The purpose of this study is to examine the clinical correlates of comorbid IED and PTSD and the contribution of these two disorders (among others) to lifetime suicide attempt and characteristics of suicidal behavior.

METHOD: In a large sample of community research volunteers (N=1460), we compared individuals with PTSD, IED, and comorbid PTSD and IED on measures of current mood, trait aggression, and trait impulsivity. We also examined the contributions of PTSD, IED, and other syndromal and personality disorders to the prediction of lifetime aggression and lifetime suicide attempt, and their relationship to characteristics of suicide attempts, including level of intent, use of violent versus non-violent means, and the medical seriousness of the attempt.

RESULTS: Comorbid PTSD and IED was associated with significantly elevated levels of depression, anxiety, anger, aggression, and impulsivity, as well as with high rates of comorbidity with other psychiatric disorders. IED (β=.56, p<.001), but not PTSD, significantly and uniquely predicted lifetime aggressive behavior. Both IED and PTSD were associated with lifetime suicide attempt in multivariate analysis (ORs: 1.6 and 1.6, ps<.05). The results show that IED, when comorbid with PTSD, identifies a subgroup of individuals with particularly high levels of aggressive behavior and a high rate of suicide attempt (41.4% in this sample).

CONCLUSION: These findings add support to the notion that the diagnosis of IED may aid in identifying individuals at risk for aggressive and suicidal behavior.