A brief summary of current research.
Bryan, C, Clemans, T, Hernandez, AM, and Rudd, MD. Journal of Head Trauma Rehabilitation: Vol 28(1), pp 13–20.
This research was conducted on a United States base in Iraq. Studying military personnel with mild TBI, researchers found that an increased risk of suicide was significantly associated with depression and the interaction of depression with the symptoms of post-traumatic stress disorder.
Looking at how depression and PTSD overlapped, researchers also found that the longer a person’s loss of consciousness, the less likely he was at risk of suicide.