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.