ARTICLE IN BRIEF
Investigators found that the relationship between depression symptoms and suicide risk was strengthened in the group of service members who'd sustained multiple traumatic brain injuries.
Service members sustaining repeated traumatic brain injuries (TBIs) are at a higher suicide risk than those who sustain just one, even when common suicide risk factors are taken into account, according to new research published in the May 15 online edition of JAMA Psychiatry.
The study also found that the relationship between depression symptoms and suicide risk was strengthened in the group of service members who'd sustained multiple TBIs.
The findings offer new insight into the well-established link between traumatic brain injuries and suicide risk and researchers say they might help provide guideposts for future care among military personnel, who are sometimes dogged by suicidal thoughts for years after service.
A May 15 article in The New York Times found that the suicide rate among members of the military has risen steadily over the 12-year period of the Iraq and Afghanistan wars. The suicide rate in the military used to be well below the civilian rate, but now the rates are nearly the same — more than 18 people for every 100,000, according to the report.
Craig Bryan, PsyD, associate director of the National Center for Veterans Studies at the University of Utah, said the study stemmed from his observations as chief of a clinic when he was on active duty for four years, through 2009, in Iraq. The data in the study, from 161 subjects, come from that clinic.
“What we found was that as service members incurred more traumatic brain injuries during their lives, the likelihood of them experiencing suicidal thoughts — both during their entire life [and] during the past year — increased significantly,” Dr. Bryan said. “In particular, those who had a history of multiple TBIs were three to four times more likely to have been suicidal during their whole life or during the past year.”
Among those who had had no TBIs during their lifetime — either in or out of the military — the incidence of suicidal thoughts was 0 percent compared with 6.9 percent for those who'd sustained a single TBI and 21.7 percent for those who'd experienced more than one TBI (p=.009).
A similar pattern was found for suicidal ideation within the past year — 0 percent for those who had not had a TBI, 3.4 percent for a single TBI, and 12 percent for those who had more than one TBI (p=.04).
He said a second TBI made a major difference — researchers initially broke out the groups into the number of TBIs but “it didn't change the results.”
“What really mattered was that second traumatic brain injury,” Dr. Bryan said. “There's something about that second injury that provides sort of a long-term vulnerability, not only in depression and anxiety, but also suicide risk.”
All of the TBIs involved with the study were mild, or concussions. It's been established that mild TBI generally causes greater suicide risk than more severe TBI — perhaps because of the type of damage caused to the brain, and perhaps because of expectations among service members and their loved ones that they should be all right since their injury was only “mild.”
When the effects of depression, post-traumatic stress disorder, and TBI symptom severity were controlled for, multiple TBIs were still associated with a greater suicide risk (p=.03).
Researchers also found that the relationship between depression symptoms and suicide risk strengthened in those with multiple TBIs.
Dr. Bryan said that if you took three patients, all with a history of TBIs, those with two or more brain injuries and depression symptoms might merit more concern. “You actually might consider them to be a little bit higher risk for suicide… even if they all kind of present in very similar ways,” he said.
Dr. Bryan said it's not a matter of discharging military personnel once they sustain a second traumatic brain injury — since most service members sustaining these injuries will be fine — but of making sure that those at heightened risk get the help they need.
Important considerations are making sure that those who've incurred TBIs get actual bed rest — a challenge in the culture of toughness in the military — and that the nature of their jobs be changed when it's required.
“Many service members, even those who have been severely injured, many of them still want to be in the military,” Dr. Bryan said. “So maybe they can't go and be in combat anymore, but they can do other jobs within the military, whether administrative, leadership, or something like that, so they can still contribute to the mission.”
POST-TRAUMATIC STRESS IS A FACTOR
Robert Ruff, MD, PhD, professor of neurology at Case Western Reserve University who has studied how multiple TBIs lead to neurological deficits in veterans, said the results sounded reasonable. A study by his team found that that the likelihood of a service member developing post-traumatic stress disorder (PTSD) was associated with the number of TBI events involving a loss of consciousness.
Dr. Ruff said the severity of PTSD might play a bigger role than the study let on. “They found that the link between TBI events and suicide risk was related to severity of depression, rather than severity of PTSD,” Dr. Ruff said. “However, given that they also found that both depression and PTSD were related to number of TBI events, it is possible that both depression and PTSD were linked to suicide risk. The noise inherent in their data may have limited their ability for a PTSD-suicide link to achieve statistical significance in their regression analysis.”
He said the study could have given more attention to increased or altered impulsivity. “My group's experience has been that the poor impulse control is a major issue associated with suicide attempts and suicide deaths,” he said. “The individuals may flip into a suicidal state following a setback and these setbacks can be unpredictable.”
Dr. Ruff cited the case of a veteran who got a note from her ex-boyfriend and thought he wanted to resume a romantic relationship. But she attempted suicide when she found out he was contacting her because he was in a 12-step program and had to contact prior acquaintances.
Remaining to be studied, Dr. Ruff said, is how the TBI events lead to depression and PTSD. “One possibility is that damage to the anterior inferior frontal cortex, including the ventromedial prefrontal cortex (vmPFC) could potentiate a depressed mood,” he said. “In addition, the vmPFC modulates the amygdala. Damage to the vmPFC will reduce inhibition of the amygdala and facilitate the genesis of anxiety and fear, leading to PTSD.”
Timothy Rice, MD, a psychiatrist at Mount Sinai School of Medicine, said the study is important in showing a direct link between multiple TBIs and suicide risk.
“The direct link is important and furthers the argument that mental health clinicians should incorporate directly inquiring about a history of TBI into the standard psychiatric assessment,” he said.
Veterans Affairs administration could incorporate a TBI assessment into their standard intake and admission interviews. And mental-health trainees should receive instruction on how to get a detailed history on TBI, including severity and its effects on function, and training on how to incorporate that information into a treatment plan.
A group out of Sydney, Australia, he notes, has developed a program, for those who've sustained a TBI, to reduce a feeling of hopelessness, a “modifiable risk factor that has been shown to have a greater predictive power for suicide than depression,” Dr. Rice said.
“Future work should focus on deficits within a neurobiologically-oriented dimensional model to better understand the mechanism of action for suicide risk in patients with TBI,” he said. “Impaired emotional regulation and resultant poor frustration tolerance may be a key target of study.”