No studies to date have examined the effects of pregnenolone on hypervigilance for social threat in individuals with perceived social isolation (PSI). We therefore are conducting a double-blind randomized research study combining three validated behavioral paradigms on social threat attention, perception of others, and emotion regulation with high-density electrical neuroimaging to probe the neuro-circuitry of social threat processing in young adults high in perceived social isolation two hours after the oral administration of 175mg pregnenolone (N = 24), 400mg of pregnenolone (N = 24), or placebo (N = 24). Such research has the potential to yield important insights into the neurobehavioral mechanisms of pregnenolone on hypervigilance for social threat and perception of others--- a first key step toward the development of adjunctive pregnenolone therapy in individuals with PSI.