The study defined premature death as dying before the age of 56.
Researchers at the Karolinska Institute in Stockholm and Oxford University reviewed data on traumatic brain injuries in Sweden among people born in 1954 or later, reports news agency AFP.
The reasons for the increased risk of early death, often involving suicide or fatal injuries, such as car accidents, remains unclear. However, study leader Seena Fazel of Oxford University said it might have to do with impaired judgment.
The findings led to a call for a longer-term approach to care for traumatic brain injury patients.
"TBI survivors should be monitored carefully for signs of depression, substance abuse and other psychiatric disorders, which are all treatable conditions," said Seena Fazel.