Suicidality and Injury of the Prefrontal Cortex in Multiple Incidents of Mild Traumatic Brain Injury

Abstract

To the Editor The article by Bryan and Clemans 1 about the relationships between episodes of combat mild traumatic brain injury (mTBI) and suicide augments information on the role of repeated traumatic brain injury episodes in the genesis of brain injury and altered behavior. 2,3 The finding of a relationship between number of mTBI episodes and the likelihood of suicidality is consistent with prior observations demonstrating that the likelihood of an individual developing posttraumatic stress disorder increased with the number of episodes of combat mTBI that were associated with loss of consciousness (LOC). 4 We found that the relationship between posttraumatic stress disorder and the number of mTBI episodes was stronger for mTBI associated with LOC compared with the number of mTBI events that were not accompanied by LOC. We wonder if Bryan and Clemans 1 can comment on whether suicidality was related more strongly to episodes of mTBI with LOC compared with episodes without LOC. We would appreciate the thoughts of Bryan and Clemans 1 on the role of impulsivity in suicidality following mTBI. Our experience has been that impaired impulse control is associated with suicide attempts following combat mTBI. Individuals may flip into a suicidal state following an unpredictable setback. For example, we treated a veteran who had sustained multiple episodes of mTBI who received a note from a former acquaintance. The veteran thought the acquaintance intended to resume a romantic relationship. The veteran attempted suicide after discovering that the acquaintance did not desire romance. The attempted suicide was done impulsively. The veteran did not contact anyone to express distress. Impulsivity can reflect altered frontal lobe function. A recent study reported increased activation of the anterior cingulate and prefrontal cortex in combat veterans with histories of suicidal ideation. 5 We found that impaired olfaction increased with the number of mTBI events associated with LOC. 4 Because the olfactory cortex is located in the ventromedial prefrontal cortex, impaired olfaction may indicate prefrontal injury. The observation that an increased number of traumatic brain injury events are associated with increased risk of suicidality suggests that such individuals, their families, and caregivers should be targeted for interventions to prevent suicide including education to encourage the veteran to alert others when thoughts of suicide emerge. Families need education about mTBI to understand that even though the veteran may