Event Related Potentials in Borderline Personality Disorder and Major Depression

This study examines whether depression in people with borderline personality disorder is different than depression in people without borderline personality disorder. Unlike people who have depression alone (i.e. without borderline personality disorder), people with borderline personality disorder have depressions that often do not improve with medications. This makes treating depression much more challenging in someone with borderline personality disorder than without borderline personality disorder. Borderline personality disorderis associated with difficulty in understanding and communicating feelings. Impaired emotion processing may reflect dysfunction of an area of the brain, the anterior cingulate. Depression is associated with changes in anterior cingulate activity. The investigators believe that when borderline personality disorder is present with depression, brain activity changes in the anterior cingulate will not be the same as in depressed patients without borderline personality disorder. An electroencephalogram records brain electrical activity. In this study, the investigators will measure electroencephalogram indices reflecting anterior cingulate activity. HYPOTHESIS: In this study, the investigators predict that when borderline personality is present with depression, electroencephalogram indices of anterior cingulate activity will be different from when depression is present alone (without borderline personality). This could help to explain why people with borderline personality have depressions that are harder to treat than depressions in people without borderline personality. The investigators also predict that electroencephalogram indices of the anterior cingulate will reflect emotional processing ability, as measured by validated questionnaires.