Neurocognitive Functioning and Impulsivity in Veterans With Bipolar Spectrum Disorders: Suicide Attempters Versus...

Objective: Veteran status and bipolar disorder (BD) are two substantial risk factors for suicide. Models of suicide implicate neurocognition and impulsivity in suicidal behavior. We aim to examine neurocognitive dysfunction and impulsivity correlates of suicide in veterans with BD.

Methods: We included 29 veterans with a DSM-5 bipolar spectrum disorder with a suicide attempt history (BD/SA+), 33 veterans with bipolar spectrum disorder without a suicide attempt history (BD/SA-), and 22 healthy control veterans (HC) recruited between January 2021 and July 2023. Participants were administered the MATRICS Consensus Cognitive Battery; Barratt Impulsivity Scale; Urgency, Premeditation, Perseverance, Sensation Seeking, Positive Urgency Impulsive Behavior Scale; and Impulsive/Premeditated Aggression Scale.

Results: BD/SA+ performed worse on working memory than BD/SA-; mean difference (MD [95% CI], -5.74 [-10.65 to -0.82], P=.034) and HC (-10.31 [-15.77 to -4.85], P < .001). BD/SA+ also performed worse on verbal learning than BD/SA- (MD [95% CI], -4.49 [-8.41 to -0.57], P = .038) and HC (-5.52 [-9.87 to -1.16], P = .038). Differences between BD/SA+ and BD/SA- in working memory remained significant when adjusting for depressive (P = .037) and manic (P = .024) symptoms, but verbal learning was no longer significantly different when adjusted for depression. BD/SA+ also had higher scores than BD/SA- on impulsive (MD [95% CI], 3.68 [0.64 to 6.73], P = .018) and premeditated (5.80 [1.51 to 10.10], P = .013) aggression. Across the BD groups, poorer working memory was associated with greater premeditated aggression (r = -0.321, P = .013) while poorer verbal learning was associated with greater impulsive (r = -0.297, P = .021) and premeditated (r = -0.372, P = .003) aggression.

Conclusion: Results suggest that in veterans with BD, poorer working memory is associated with suicide attempt independent of depression, while verbal learning impairments associated with suicide attempt may be influenced by depression. Neurocognitive dysfunction may underlie aggression to drive suicidal behavior. Findings support the role of neurocognition in models of suicide in BD and can inform risk detection and intervention.