Use of 31P MRS to Assess Brain NAD+ in Healthy Current and Former Collegiate Athletes

Inclusion Criteria: * Adult current and former (within 2 years) collegiate athletes (football, rugby, soccer, hockey, and volleyball) * Body mass index (estimated based on height and weight) from 23 to 37 * Willing to provide informed consent, ingest test substance, and provide blood specimens * Willing to comply with study instructions and maintain current level of physical activity throughout the study Exclusion Criteria: * History of loss of consciousness of more than 5 minutes * Contraindications to Magnetic Resonance Imaging (MRI), such as implanted medical devices, metal objects, or pacemakers * History of epilepsy * History of more than 3 concussions * History of headache preceding a concussion * History of depression preceding a concussion * History of developmental delays or Attention Deficit Hyperactivity Disorder (ADHD) * History of post-traumatic seizures * History of complex spine and/or skull trauma