Borderline personality disorder (BPD) is characterized by impulsivity with emotional and behavioral dysregulation. Inappropriate anger becomes a central problem of these patients who underwent aggressive behavior against themselves or against other. Impulsive aggression has been consistently related with serotonergic dysfunction. Drug therapy with SSRIs has proven effective in treatment of impulsive aggression in varying amounts, but still there have not been described clinical predictors of good response to this treatment. Is known that neuroticism is a stable trait in BPD, also related to serotonergic dysfunction.

To investigate the relationship between neuroticism and clinical response to fluoxetine in impulsive aggression in BPD. We hypothesized that the level of neuroticism at baseline may predict aggression response to pharmacologic treatment.

59 patients were recruited, all meet DSM IV criteria for BPD according to IPDE. They did not fulfill criteria for axis I diagnoses or other personality disorders. Patients were treated with fluoxetine (Prozac®) for 12 weeks, in doses 20 to 60 mg. Aggression was measured with OAS-M.

Temperament was evaluated with NEO-PI-R.

Multiple regression analysis of OAS-M reduction at endpoint as dependent variable, and temperament as independent variables shown a significant predictive model with neuroticism as an inverse predictor factor (ß = −0.36, p = 0.005). We discusses that high levels of neuroticism at baseline can predict lower aggression response to fluoxetine, perhaps due to the relationship of both disorders with serotonergic dysfunction.

We can conclude that neuroticism is a relevant predictor of impulsive aggression response to treatment with SSRIs in BPD.