Data were derived from 897 participants (513 women, mean age 19.62±1.24) who had successfully completed the ongoing Duke Neurogenetics Study (DNS) as of as of December 31, 2013. The DNS assesses a range of behavioral and biological traits among young adult, university students. The study was approved by the Duke University School of Medicine Institutional Review Board. All participants provided informed consent in accord with Duke University guidelines, and were in good general health. All participants were free of the following exclusionary criteria: (1) medical diagnoses of cancer, stroke, diabetes requiring insulin treatment, chronic kidney or liver disease, or lifetime history of psychotic symptoms; (2) use of psychotropic, glucocorticoid, or hypolipidemic medication; and (3) conditions affecting cerebral blood flow and metabolism (e.g., hypertension).
