Abstract: Suicide remains an urgent concern of the Department of Veterans Affairs (VA). Uridine is a novel treatment with a broad mechanistic overlap with ketamine and lithium, two drugs with anti-suicidal effects. The aims of this double blind randomized controlled clinical trial VA-funded study are to determine if uridine decreases suicidal ideation (SI) in Veterans, and to measure rapid changes in GABA, Glutamate, and Glutamate+Glutamine (Glx) associated with uridine compared to placebo.