Traumatic Brain Injury (TBI) caused by high-speed transportation accident results in mechanism of injury described as Diffuse Axonal Injury (DAI), which is associated with reduction in dopamine turnover in brain. The effect of Amantadine on functional improvement in patients with traumatic brain injury is not apparent at 4 to 6 weeks of treatment. There was a consistent trend toward a more rapid functional improvement regardless of when a patient with DAI-associated TBI was started on amantadine in the first 3 months after injury. Studies with large sample size are needed to establish its neuroprotective effect.