Clinical features associated with trait-impulsiveness in euthymic bipolar disorder patients

Background: A strong association has been reported between trait-impulsiveness and bipolar disorder (BD). Much attention has been focused on this association, but subgroup analysis has generated conflicting results, raising questions about the role of trait-impulsiveness in suicidal behavior and substance misuse in bipolar patients. Method: We compared Barratt Impulsiveness Scale-10 scores between 385 euthymic bipolar patients and 185 healthy controls. We then investigated possible association between impulsiveness scores and the following clinical characteristics: suicide attempt (SA), lifetime alcohol/cannabis misuse, rapid cycling and mixed episodes. Results: Bipolar patients and healthy controls had significantly different BIS-10 total score and subscores (motor, attentional and nonplanning impulsiveness) (all p values <0.0001). No association was observed between BIS-10 total score, personal history of SA, number of SA, age at first SA and history of violent SA. Higher BIS-10 total scores were associated with alcohol misuse (p=0.005), cannabis misuse (p <0.0001), with an additive effect for these two substances (p=0.005). Higher BIS-10 total scores were also associated with rapid cycling (p=0.006) and history of mixed episodes (p=0.002), with an additive effect of these two variables (p=0.0006). Limitations: We used only one clinical measurement of impulsiveness and did not carry out cognitive assessment. Conclusion: This study demonstrates that trait-impulsiveness may be considered as a dimensional feature associated with BD and with a more severe clinical expression of the disease, characterized by a history of substance misuse, rapid cycling and mixed episodes. We found no association between impulsiveness and SA characteristics in bipolar patients, confirming some previous negative results. (C) 2012 Elsevier B.V. All rights reserved.