Project Summary. Intravenous ketamine, which displays rapid antidepressant and anti-suicidality properties, is posited to reverse symptoms by rapidly enhancing neuroplasticity; but surprisingly little is known regarding its feasibility, safety, and effectiveness for reducing suicidal outcomes among real-world, heterogenous samples at imminent risk. Furthermore, a significant barrier to clinical adoption is the lack of evidence for durability of ketamine's effects, raising concerns about illusory recovery and subsequent rebound of suicide risk. We posit that ketamine will rapidly decrease suicidal ideation and rapidly increase cognitive flexibility in a real-world sample, allowing for rigid, negative biases in cognition to be rapidly reversed. We further expect these neurocognitive changes will provide a clinical window of opportunity in which to introduce 1) standard crisis-oriented psychiatric care; and 2) automated cognitive training (CT) techniques, which will consolidate adaptive forms of cognitive processing (specifically, positive and life-oriented implicit representations of self) while neuroplasticity remains high. Instantiating adaptive forms of processing (through standard care and/or automated CT) after first 'priming' the brain with ketamine represents a potentially synergistic treatment approach that could extend the acute effects of a single ketamine infusion beyond its typical 3-7 day window, efficiently fostering protective anti- suicidal effects that are both rapid and enduring. In this study, 200 Medical Unit inpatients (age 18-65) will be enrolled by referral from the psychiatric consultation/liaison service in a large Level 1 trauma hospital, following consult for a medically serious suicide attempt (SA). Leveraging medical unit physicians who are well-accustomed to utilizing ketamine infusion routinely in their inpatient medical settings, inpatients will be randomized in a parallel arm design to receive a single infusion of ketamine “pre-treatment”—shortly prior to subsequent psychiatric inpatient stay—or no- infusion. Patients will complete acute measures of explicit SI and cognitive target engagement (implicit suicide-self associations; Aim 1). In a fully crossed (2 x 2 factorial), parallel arm design, patients will then be randomized to receive a brief web-app-based cognitive training protocol during the post-infusion "window of opportunity," designed to implicitly reverse negative self-representations, instilling beneficial self-representations in their place, or a sham variant of the same training. Patients, investigators, and outcome raters will be blinded to treatment condition. Comprehensive feasibility/safety data will be captured for both intervention components. Remote assessments and the medical record will then be used to capture SI and SAs over a 12-month naturalistic follow-up to assess whether: ketamine followed by standard psychiatric inpatient care has a beneficial impact over no-infusion standard-of-care (Aim 2) and active cognitive training enhances and/or extends the durability of ketamine's effects, potentially providing an exceedingly efficient, low- cost, portable, non-invasive, safe, and highly dissemination-ready strategy (Aim 3). This study will provide novel feasibility, safety, and effectiveness data on ketamine's impact among heterogeneous real-world patients at imminent risk of suicide, and will represent a first attempt to synergistically combine ketamine with both standard and novel (cognitive training) interventions in a real-world, generalizable setting, in an effort to exploit and extend ketamine's rapid effects.

Project Narrative This project seeks to test the feasibility, safety, and effectiveness of delivering intravenous ketamine to medical unit inpatients who are hospitalized following a medically serious suicide attempt and require subsequent inpatient psychiatric treatment. We will test whether a single infusion of ketamine rapidly reduces suicidal thoughts in this group, and whether it promotes the uptake of helpful information delivered either through the course of subsequent, standard psychiatric inpatient care and/or through a computer-based cognitive training app. This work could ultimately lead to the ability to treat suicide risk more efficiently by rapidly priming the brain for helpful forms of learning.