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Individuals with intermittent explosive disorder, as well as people with a history of suicidal or self-injurious behavior, were found to be twice as likely to have a history of mild traumatic brain injury (mTBI) than those with other psychiatric disorders or healthy controls, according data from a study by Emil F. Coccaro, M.D., of the University of Chicago and Caterina Mosti, Ph.D., of Drexel University.
Mild TBI is highly prevalent, with more than 1.3 million injuries occurring in the United States each year. Additionally, some 15% of returning military service personnel are estimated to have sustained an mTBI. Since many people who experience mild head injury do not seek medical treatment, this is likely a significant underestimation, the authors wrote. While the resulting cognitive, physical, and emotional consequences typically resolve within three months of the injury, a growing body of research suggests that 10% to 31% of those with mTBI injuries suffer lingering physical symptoms and mood disturbances.
To explore the relationship between history of mTBI and aggression, the researchers interviewed 1,634 physically healthy adults (this group included 695 participants with intermittent explosive disorder, 486 participants with a current/lifetime diagnosis of a psychiatric disorder that was not intermittent explosive disorder, and 453 with no psychiatric disorder). During these interviews, study participants were asked to report any history of mTBI (defined as a blow to the head associated with mild neurological symptoms including any of the following: dizziness, disorientation, memory difficulties lasting less than 24 hours, or loss of consciousness of less than 30 minutes). The participants were also asked questions about aggressive and impulsive behaviors.
Among patients who had a mTBI, 11% had no evidence of psychiatric disorder, 12% had a psychiatric or personality disorder (other than bipolar or schizophrenia/psychotic disorders), and 24% had intermittent explosive disorder. About 25% of those with mTBI had suicidal and/or self-injurious behavior. Participants reporting two or more loss of consciousness episodes had the highest aggression scores of all groups.
“On the basis of these data alone, we cannot say whether the presence of high trait impulsivity and aggression led IED [intermittent explosive disorder] participants to be in circumstances that increase risk for mTBI or whether history of mTBI altered the brains of mTBI participants, leading to an increase in aggressive and impulsive behavior post-mTBI,” the authors wrote. “That said, impulsive-aggressive behaviors are present from very early life, and individuals with this temperament are likely to place themselves in circumstances associated with bodily injury, including mTBI.”
For related information on aggression following TBI, see the Psychiatric News article “Amantadine May Reduce Aggression in TBI Patients.”
(Image: Olimpik/Shutterstock)
