Lithium reduces impulsive decision making in transdiagnostic patients at high risk for suicide attempt recurrence: A randomized, double blind, placebo-controlled, crossover study

Background: Studies attempting to distinguish suicide attempters from ideators have found that impulsivity is consistently associated with attempts across the spectrum of suicidal behavior from self-harm to lethal suicidal behavior. Impulsivity is readily assessed using complementary clinical and laboratory measures, making it a viable target for pharmacological strategies to prevent suicide risk. Lithium reduces suicidal behavior across diagnoses, and has been implicated in the reduction of impulsivity triggered by stress mediated phosphatidylinositol turnover. We used a placebo controlled cross-over design to study the effects of repeated lithium dosing on risk factors predisposing to suicidal behavior. Methods: 15 patients with a recent (past year) medically severe suicide attempt (MSSA) (37.5% male, 40.13 ± 13.66 years) received lithium carbonate and matching pill placebo separately in a randomized double-blind crossover design administered six weeks apart. To test the effect of lithium on measures of impulsivity and arousal, participants completed the Immediate Memory Task (IMT), Internal State Scale (ISS), and the Time Perception Task (TPT). We conducted separate analyses for each variable using repeated measures analysis of covariance. Results: Lithium dosing was associated with increased IMT response latency (p = .017, pη2 = 0.23), and decision bias (p = .048, pη2 = 0.21). Lithium did not significantly alter time perception or activation. Conclusions: Our results suggest that lithium may reduce risk in MSSA survivors by increasing the response latency and increasing conservative response bias during decision-making. Future studies should conduct long-term follow-ups with adjunct behavioral therapy with lithium on factors contributing to suicidal behavior.