A preliminary investigation of impulsivity, aggression and white matter in patients with bipolar disorder and a suicide attempt history

Background: Impulsivity and aggression may be associated with suicide attempts in bipolar disorder (BD), but findings have been inconsistent. Abnormalities in anterior white matter tracts that project to the frontal lobes mediate top-down regulation of emotion and may contribute to this clinical phenomenology. Methods: We assessed white matter (i.e., fractional anisotropy) in anterior and posterior brain regions using diffusion tensor imaging in 18 patients with BD and no prior suicide attempt (BD-S), 12 patients with BD and a prior suicide attempt (BD + S), and 12 healthy volunteers. Patients completed the Urgency, Premeditation, Perseverance, Sensation Seeking, Positive Urgency (UPPS-P) Impulsive Behavior Scale and Impulsive Premeditated Aggression Scale (IPAS). All individuals completed the Barratt Impulsiveness Scale (BIS-11). Results: Patients with BD + S had higher overall impulsivity (assessed using both the UPPS-P Impulsive Behavior Scale and BIS-11) and premeditated aggression compared to patients with BD-S. There were no significant group differences on measures of fractional anisotropy (FA). In patients with BD + S, however, higher FA in the anterior (but not the posterior) brain regions correlated with greater overall impulsivity on the UPPS-P Impulsive Behavior Scale. There were no significant correlations between either anterior or posterior brain regions with clinical measures in patients with BD-S. Limitations: Cross-sectional study, sample size and possible contribution of psychotropic medications. Conclusion: Impulsivity and aggression may be risk factors for a suicide attempt in BD. White matter in the anterior limb of the internal capsule and anterior corona radiata may play a role in this phenomenology.