Survivors of traumatic brain injuries (TBI) are three times more likely to die prematurely than the general population, often from suicide or fatal injuries, according to an Oxford University-led study.
A TBI is a blow to the head that leads to a skull fracture, internal bleeding, loss of consciousness for longer than an hour or a combination of these symptoms.
The recent skiing accident that left Formula one legend Michael Schumacher in a coma is an example of a TBI.
Researchers at Oxford University and the Karolinska Institute in Stockholm examined Swedish medical records going back 41 years covering 218,300 TBI survivors, 150,513 siblings of TBI survivors and over two million control cases matched by sex and age from the general population.
"We found that people who survive six months after TBI remain three times more likely to die prematurely than the control population and 2.6 times more likely to die than unaffected siblings," said study leader Dr Seena Fazel, a Wellcome Trust Senior Research Fellow in Oxford University's Department of Psychiatry.
"Looking at siblings who did not suffer TBIs allows us to control for genetic factors and early upbringing, so it is striking to see that the effect remains strong even after controlling for these," Fazel said.
The results, published in the journal JAMA Psychiatry, showed that TBI survivors who also have a history of substance abuse or psychiatric disorders are at highest risk of premature death.
Premature deaths were defined as before age 56. The main causes of premature death in TBI survivors are suicide and fatal injuries such as car accidents and falls.
"TBI survivors are more than twice as likely to kill themselves as unaffected siblings, many of whom were diagnosed with psychiatric disorders after their TBI," said Fazel.
"Current guidelines do not recommend assessments of mental health or suicide risk in TBI patients, instead focusing on short-term survival," Fazel said.
"TBI survivors should be monitored carefully for signs of depression, substance abuse and other psychiatric disorders, which are all treatable conditions," Fazel said.
The reasons for the increased risk of premature death are unknown but may involve damage to the parts of the brain responsible for judgement, decision-making and risk taking.
"This study highlights the important and as-yet unanswered question of why TBI survivors are more likely to die young, but it may be that serious brain trauma has lasting effects on people's judgement," said Fazel.
Concussions, sometimes called mild TBIs, were analysed separately in the study. People with concussion were found to be twice as likely to die prematurely as the control population, with suicide and fatal injuries as the main causes of death.