Imaging [18F]PI-2620 and [18F]Florbetaben in Military Service Members With Blast Related Mild Traumatic Brain Injury

Inclusion Criteria: 1. Male 2. Right-handed 3. Age 25-54 4. Agree to participate in ALL study procedures 5. English speaking 6. Ambulatory 7. Must be able to identify a study partner who is well acquainted with the participant for at least 2 years, to answer questions either in person or over the telephone about the participants' activities of daily living, and to corroborate behavioral and cognitive problems and history of brain injury 8. History of combat deployment 9. For blast-related mTBI group: must be active duty or DEERS-eligible, currently or formerly enrolled in the 4 week intensive outpatient program at NICoE, have experienced 1 or more blast-related mTBIs during tours of duty and report experiencing changes in mood, behavioral or cognitive problems (blast-related mTBI considered here and confirmed in EMR as: blast exposure from explosive device resulting in mTBI which fits criteria defined by VA DoD mTBI guidelines which include at least one of: at time of injury - LOC 0-30 minutes, AOC up to 24hrs, PTA 0-1 day, GCS 13-15) 10. DEERS-eligible for all participants 11. For control group 1: history of mTBI with no blast-related mTBIs (as confirmed in EMR and/or by the BISQ and QCube) 12. For control group 2: No lifetime history of TBI (as confirmed by the BISQ and/or EMR) Exclusion Criteria: 1. Had a moderate or severe brain injury that required hospitalization 2. Significant systemic illness or unstable medical conditions including: uncontrolled diabetes mellitus, uncorrected hypothyroidism or hyperthyroidism, or systemic cancer 3. Diagnosis of schizophrenia, psychosis, or other psychological disorder (Note: blast-related mTBI group will not be excluded if they have a stable diagnosis of post-traumatic stress disorder, depression and anxiety resulting from their military experience; disorders existing prior to military service will serve as an exclusion) 4. Current and active alcohol or substance abuse or dependence (DSM V criteria) within the past 6 months 5. Clinically significant laboratory test abnormalities (such as hematology, chemistry, urinalysis, ECG) or significant impairment of liver or renal function 6. Significant cerebrovascular disease (such as TIA, stroke) or cardiovascular disease (such as uncontrolled hypertension, atrial fibrillation) 7. Impairment of visual or auditory acuity sufficient to interfere with completion of study procedures 8. Education level \< 10 years 9. The presence of any MRI-incompatible prostheses or ferromagnetic metal, or any other condition that would preclude ability to undergo MRI or PET (such as claustrophobia or obesity, \>350 lbs and/or unable to fit in scanners) 10. History of risk factors for torsade de pointes or take drugs known to prolong the QT interval 11. Had 2 or more PET scans in the last year, or other significant exposure to radiation (i.e. radiation therapy) 12. Diagnosis of neurodegenerative or neurological diseases and dementia (other than CTE) such as Alzheimer's disease, Parkinson's disease, vascular dementia, Huntington's disease, Pick's disease, Lewy Body Dementia, frontotemporal dementia, normal pressure hydrocephalus, brain tumor, progressive supranuclear palsy, seizure disorder, or multiple sclerosis