Allopregnanolone in Chronic Complex Traumatic Brain Injury

Inclusion Criteria: * 21-62 years of age, any ethnic group, either sex * History of mild TBI since 2001 and service in the U.S. Military since 9/11/01 (OEF/OIF/OND era) * The investigators will adhere to the operational definition of mild TBI suggested by the World Health Organization Task Force, with the exception of seizure and Glasgow Coma Scale score criteria (not available for these participants) with 1 or more of the following: * confusion or disorientation * loss of consciousness for 30 minutes or less * post-traumatic amnesia for less than 24 hours * and/or other transient neurological abnormalities such as focal signs, and intracranial lesion not requiring surgery * Ability to participate fully in the informed consent process * HAM-D score 14 (HAM-D range for moderate depression=14-18) * Participants will meet DSM-5 criteria for major depressive disorder (by SCID) * The presence of psychotic features will be exclusionary * Single episodes or recurrent episodes will be permissible for study entry (the investigators will examine treatment responses in those who have had single depressive episodes versus those who have had multiple depressive episodes in exploratory sensitivity analyses * BPI (Brief Pain Inventory, Short Form) 'current' pain intensity rating item score 4 (scale of 0-10) * Pain must be musculoskeletal in nature * No anticipated need to alter psychiatric medications for 14-day duration of study involvement * No changes in psychotropic or…