Suicidal behavior and mild traumatic brain injury in major depression.

Traumatic brain injury (TBI) is associated with psychiatric illness, suicidal ideation, suicide attempts, and completed suicide. We investigated the relationship between mild TBI and other risk factors for suicidal behavior in major depressive episode. We hypothesized that mild TBI would be associated with suicidal behavior at least partly because of shared risk factors that contribute to the diathesis for suicidal acts. Depressed patients (N = 325) presenting for treatment were evaluated for psychopathology, traumatic history, and suicidal behavior. Data were analyzed using Student t -test, chi-square statistic, or Fisher exact test. A backward stepwise logistic regression model (N = 255) examined the relationship between attempter status and variables that differed in the TBI and non-TBI patients. Forty-four percent of all subjects reported mild TBI. Subjects with TBI were more likely to be male, have a history of substance abuse, have cluster B personality disorder, and be more aggressive and hostile compared with subjects without TBI. They were also more likely to be suicide attempters, although their suicidal behavior was not different from that of suicide attempters without TBI. Attempt status was mostly predicted by aggression and hostility, but not the presence of TBI. Of note, for males, a history of TBI increased the likelihood of being a suicide attempter, whereas the risk was elevated for females regardless of TBI history. Our data suggest that suicidal behavior and TBI share antecedent risk factors: hostility and aggression. Future studies may yield confirmation using a prospective design.