Prazosin and Cerebrospinal Fluid (CSF) Biomarkers in Mild Traumatic Brain Injury (mTBI)

Mild traumatic brain injury (mTBI) from explosions is the "signature injury" of Veterans who have deployed to the wars in Afghanistan and Iraq. Although the immediate effects of a single mTBI usually resolve over days or weeks, multiple mTBIs can lead to both persistent symptoms and, years later, to two fatal progressive brain diseases, chronic traumatic encephalopathy (CTE) and Alzheimer's disease (AD). It is believed that CTE and AD are caused by nerve damaging chemicals called tau and beta amyloid produced by the brain but which are not removed from the brain in a normal manner in persons with mTBIs. The investigators will determine in Veterans who experienced mTBIs whether a clinically available drug called prazosin increases removal of tau and beta amyloid from the brain. This will be accomplished by seeing if prazosin reduces the amount of tau and beta amyloid in the spinal fluid that surrounds the brain. If the investigators find such reductions, prazosin will be evaluated as a preventative treatment for CTE and AD in future studies.