Properly Diagnosing, Treating Patients With Bipolar Disorder and/or Borderline Personality Disorder

A proper diagnosis between bipolar disorder and borderline personality disorder have important implications as treatment decisions differ based on the diagnosis. Moreover, some of these patients may actually have both disorders. The American Journal of Managed Care^® (AJMC^®) recently spoke with Mark Zimmerman, MD, professor of psychiatry and human behavior at Brown University, about ensuring proper diagnosis, the prevalence of having both disorders, and the role of family history.

AJMC^®: What are the consequences of not differentiating between bipolar disorder and borderline personality disorder?

The importance of differential diagnosis very much relates to treatment. The cornerstone of treatment for bipolar disorder is pharmacotherapy with psychotherapy being an important adjunct, whereas the cornerstone of treatment for borderline personality disorder is psychotherapy with pharmacotherapy being a potentially important adjunct. So, if you make the incorrect diagnosis, you may very well not be delivering the appropriate level of care.

Someone who has been misdiagnosed as having bipolar disorder and has been on a number of different medication through the years and has been frustrated by not improving with the treatment, upon learning that they may well instead have borderline personality disorder and the focus should be on psychotherapy and their difficult childhood and their impulsive behaviors and self-regulation, all of which get addressed in psychotherapy, can have a profound impact. Likewise, if you misdiagnose someone with bipolar disorder and you potentially are exposing them unnecessarily to medication side effects. In contrast, if you diagnose someone with borderline personality disorder instead of bipolar disorder, you probably will not be delivering effective pharmacotherapy and there’s a risk of a person developing a manic or hypomanic episode and the potential negative consequences of that.

AJMC^®: What are best practices for ensuring proper diagnosis? What symptoms indicate one diagnosis or the other?

Do an adequate job of assessing the diagnostic criteria. It’s important to realize that individuals with both of these disorders most commonly present for treatment with symptoms of depression, so to diagnose bipolar disorder for someone who’s presenting with depression, it’s necessary to inquire about historical episodes of manic or hypomanic episodes. Even then, some patients may not recall having gone through that and it’s certainly useful to also have a family member come in and ask similar questions.

With respect to borderline personality disorder, for someone who is coming in for the treatment of depression, we actually did some research looking to see is there a criterion of this diagnosis that could be used as a screen for the disorder and found that the effect of instability criterion is present of 93% of our patients. It has a negative predictive value of 99%, meaning if a person screens negative, only 1% of such individuals will actually have borderline personality disorder, so that’s a very effective screen. And, if a person screens positive, then it’s necessary to ask questions to assess the other defining features of the disorder.

AJMC^®: How prevalent is it to have both disorders, and does this make it harder to ensure a correct diagnosis?

Approximately 20% of individuals with 1 of these diagnoses has the other. Let me get more specific than that. About 10% of individuals with borderline personality disorder have bipolar 1 disorder and about 10% have bipolar 2 disorder, and this comes from a larger review that we did in our program as part of the Rhode Island Methods to Improve Diagnostics Assessment Services, or MIDAS, Project, and we published this a few years ago. With respect to the frequency of borderline personality disorder in patients with bipolar disorder, about 10% of individuals with bipolar 1 disorder and about 20% of individuals with bipolar 2 disorder have borderline personality disorder.

I think the important thing is for clinicians to realize that it’s not an either or, that a significant amount of individuals with one of these diagnoses has the other. For years, there’s been discussion and debate as to whether or not borderline personality disorder belongs as part of the bipolar spectrum. In the past decade, there have been more than 2 dozen studies that have come out comparing patients with both of these disorders, and it’s pretty clear that these are distinct and valid diagnoses, so the bipolar spectrum concept with respect to borderline personality disorder has pretty much been rejected, and a number of reviewers of this literature recently have concluded that no, borderline personality disorder is not a form of bipolar disorder.

So, accepting the fact that these are 2 distinct disorders is an important to realize that some individuals, a minority to be sure, but some individuals actually have both. Sometimes it’s not immediately apparent, so it’s important for the clinician to be vigilant and continue to reassess over time. Certainly, there may will be individuals who present with depression, you diagnose them with borderline personality disorder, you treat them perhaps with an antidepressant and over time, a hypomanic episode emerges.

It’s certainly happened to me, and I will switch the diagnosis over to bipolar 2 disorder and upon treating that, their hypomanic may resolve, their mood symptoms get better, but the characteristic features of borderline personality disorder, such as impulsivity, a sense of emptiness, a lack of sense of self, difficulty and hypersensitivity in relationships—those continue and those become the focus of psychotherapy.

AJMC^®: Do these disorders impact certain demographics more than others? And how much of a role does family history and genetic play in this?

Family history does in fact distinguish the 2. Individuals with bipolar disorder tend to have increased family histories of bipolar disorder. Individuals with borderline personality disorder will have increased family histories of post-traumatic stress disorder, substance use disorders. Individuals with both of these disorders actually have elevated rates of all of those problems. As for genetic markers, there are no genetic markers for either of these.

Demographics—both of these disorders present young. Borderline personality disorder has an earlier age of onset than bipolar disorder. Borderline personality disorder is characterized by a female predominance whereas bipolar disorder is more equally distributed amongst genders. Those are perhaps the 2 most noteworthy demographic correlates.