Results from a long-term study indicate that borderline personality disorder (BPD) and bipolar disorder do not commonly coexist, a finding which has important implications for treatment. The findings are reported in the July 2006 issue of The American Journal of Psychiatry (AJP), the official journal of the American Psychiatric Association (APA).

BPD is a long-term, pervasive pattern of impulsive behavior, instability and changeable mood. Whether it is a variant of bipolar disorder is the focus of the AJP article, "Descriptive and Longitudinal Observations on the Relationship of Borderline Personality Disorder and Bipolar Disorder" by John G. Gunderson, M.D., medical director for the Borderline Personality Disorder Treatment Center at McLean Hospital.

The study found only modest connections to bipolar disorder among 196 patients with BPD. The rate of co-occurring bipolar disorder in these patients was 19 percent. In patients with other personality disorders, the rate was eight percent. Among the patients who did not have bipolar disorder at the beginning of the study, eight percent of the BPD patients developed bipolar disorder over the next four years, compared to three percent of the patients with other personality disorders.

Despite these differences, the rates of bipolar disorder in the BPD patients remained under 20 percent. This low frequency has important implications for treatment, as many BPD patients receive only a diagnosis of bipolar disorder and the two diagnoses generally are treated with different approaches. Psychosocial interventions are important in the treatment of BPD, whereas medication is generally the first choice for bipolar disorder.

"The diagnosis of borderline personality disorder arose from psychoanalytic psychotherapy practice, whereas bipolar disorder is the subject of intensive neurobiological research and psychopharmacological treatment," stated Robert Freedman, M.D., AJP editor-in-chief. "This study is an important step in examining the extent of overlap between the two disorders."

The co-occurrence of bipolar disorder did not worsen the course of BPD over four years. Remission occurred in two-thirds of both the BPD patients with and without bipolar disorder.

In an accompanying editorial, Michael H. Stone, M.D., of Columbia University notes the article's "more balanced position on the controversy" about the relationship of borderline personality to bipolar disorder. He suggests that the moderately higher rates of bipolar disorder in patients with BPD disorder may indicate a subgroup of BPD patients with higher genetic risk for bipolar disorder.