Rational drug treatment for personality disorders

The drug treatment of personality disorders is becoming popular. Despite this, almost all studies have been with borderline personality disorder, a heterogeneous group of disorders with multiple comorbid pathology that makes it difficult to be certain in which domain the benefits of treatment are being shown. Antipsychotic and antidepressant drugs are those with the greatest amount of evidence, but this falls short of a firm recommendation and the evidence that a minority of individuals may be made worse by such treatment adds to doubt. However, where there is evidence of aggression and impulsivity, and schizotypal and paranoid features within the personality disturbance, antipsychotic drugs - both typical and atypical - may have a place in treatment, although this may not be appropriate in the longer term. Most of the antidepressant evidence for efficacy comes from SSRIs but there have been very few published studies with typical antidepressants; the best results have been shown with monoamine oxidase inhibitors, drugs which are conventionally avoided in those who self-harm, as is common in borderline personality disorder. Mood stabilizers such as lithium, carbamazepine and sodium valproate have also been tested in small and generally unsatisfactory controlled trials and show some slight evidence of benefit. Benzodiazepine drugs may help cluster C personalities but with a high risk of dependence. Although there is significantly more information available now than there was some years ago, there is insufficient evidence for any firm guidance to be given on drug treatment; patient-based evidence may be of more value than evidence-based practice in determining the choice of treatment.