Monitoring Patients With Repetitive Head Impact With Gamma-glutamylcysteine Supplementation

Inclusion Criteria: * Retired NFL player, retired Navy SEAL/army personnel with combat experience exposed to repetitive head impact; * Memory and behavioral complaint per self- or informant-report; * Age (30 to 70 years of age) years; * Able to read and write in English and to give consent to participate in the study. Exclusion Criteria: * Presence of pacemakers, aneurysm clips, artificial heart valves, ear implants, metal fragments in the eyes, skin, or body. * Subjects with claustrophobia. * Subject with mild cognitive impairment \[TICS score of 29 or lower OR \>=1.0 standard deviations below age-expectation on at least two cognitive members within the same cognitive domain (e.g. memory, attention, etc.) on the baseline neuropsychological testing; * Subjects with a history of cancer; * Subjects with active psychosis or delirium; * Subjects with chronic kidney (creatinine \> 1.5mg/dL) or liver disease (AST ≥ 1.5 ULN; ALT ≥1.5 ULN) within 30 days prior to enrollment; * Subjects on antioxidant therapy (gingko biloba or N-acetylcysteine) or illicit drug abuse/dependence (cocaine, heroin, marijuana, or fentanyl; * Repeated head injury patients with neurosurgical intervention and; * Subjects with repeated head injury within the last 90 days.