Impulsivity and Aggression: A Predictive Model of Suicide in Bipolar Disorder
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Background: Impulsivity and aggression have been identified as major predictors of suicide in individuals with bipolar disorder. The aim of the current study was to develop a predictive model of suicide in bipolar disorder using these predictors.;Methods: Participants were 18 bipolar patients without a prior suicide attempt (BP-NS), 12 bipolar patients with a prior suicide attempt (BP-S) and 12 healthy controls (HC). Patients received the Impulsive Premeditated Aggression Scale (IPAS) and Urgency Premeditation Perseverance Sensation Seeking Scale (UPPS-P) and all individuals received the Barratt Impulsiveness Scale (BIS-11) and Buss Perry Aggression Questionnaire (BPAQ).;Results: Group differences were found for BIS-11 total score (F(2,39) = 7.86,p = .001). Bootstrapped multiple comparisons showed significant differences between BP-NS and HC (DeltaM = 11.67, BCa 95% CI [4.51, 18.76], d = 1.04) and BP-S and HC (DeltaM = 22.0, BCa 95% CI [11.31, 33.38], d = 1.55). While the two bipolar groups did not significantly differ on impulsivity (DeltaM = 10.33, BCa 95% CI [-0.99, 22.59], d = 0.68), there was a medium to large effect size in this comparison. While there was no group difference for BPAQ total score (F(2,39) = 2.05, p = .143), bootstrapped comparisons revealed that BP-S had significantly more total aggression than HC, DeltaM= 14.14, BCa 95% CI [3.33, 25.23], d = 0.99. Finally, BP-S had significantly more premeditated aggression than BP-NS, DeltaM= -21.28, BCa 95% CI [-40.59, -1.71], d= .94.;BIS-11 showed the strongest classification accuracy, determined by the area under a receiver-operating-characteristic (ROC) curve (AUC): ( BP-S vs. HC: AUC = .896, 95% CI [.771, 1.000]; BP-NS vs. HC: AUC = .782, 95% CI [.612, .953]; BP+/-S vs. HC: AUC = .828; 95% CI [.689, .966]).;Conclusions: These results replicate previous work indicating that impulsivity may predict suicidal behavior among individuals with bipolar disorder. Individuals with bipolar disorder were found to be more aggressive than healthy controls, but aggression did not predict suicidality. Interestingly, patients with bipolar disorder and suicide attempt histories had more premeditated, or planned, aggression, than those without attempt histories. These findings have implications for further research and treatment.