The proposed projects will examine the efficacy of nitrous oxide in relieving Veteran's PTSD symptoms and in parallel, explore whether nitrous oxide improves cognitive and pain outcomes. Specifically, the investigators will first assess whether nitrous oxide treatment improves PTSD symptoms within 1 week. In parallel, the investigators will explore whether the treatment improves co-existing depression and pain. In addition, the investigators will explore nitrous oxide's effects on a PTSD-associated impairment that is often overlooked - disruption in cognitive control, a core neurobiological process critical for regulating thoughts and for successful daily functioning.
