This study is designed to investigate whether guanfacine (Tenex) is an effective treatment for borderline personality disorder (BPD), an illness often characterized by unstable mood and impulsive aggression. Guanfacine stimulates activity in the front portion of the brain, a region associated with attention and the control of behavior. We believe that guanfacine may improve symptoms of BPD by improving attention and aiding regulation of behavior.

This is an 8-week treatment study designed to test whether guanfacine is an effective treatment for borderline personality disorder (BPD). Prior to taking the study medication, subjects will have medical and psychiatric evaluations, complete self-report questionnaires, do a functional MRI scan, and complete a set of cognitive tests. While taking the study medication, participants will meet weekly with a study doctor and be administered interviews and questionnaires. At the end of the 8-week trial, participants will be asked to repeat the MRI scan and cognitive tests.

Inclusion Criteria: This study includes men and women between the ages of 18 and 55 who meet criteria for borderline personality disorder with impulsive aggression.

Exclusion Criteria: Subjects must not currently be taking any psychiatric medications. Subjects must not meet criteria for current substance dependence, current major depression, bipolar disorder, or schizophrenia-spectrum disorders.