Borderline Personality Disorder and Bipolar Disorder

In addition to often being referred to by the same acronym (BPD), bipolar disorder and borderline personality disorder share other superficial similarities that make it easy to confuse the two. Borderline personality disorder, which I’ll call BPD here, is a very complex disorder characterized by problems with negative emotions and emotional regulation and a damaged sense of self, all of which combine to cause relationship problems and put individuals with BPD at much higher risk of self-destructive behaviors such as addiction, eating disorders, self-harming behaviors such as “cutting” and repeated suicidal behaviors. Primarily, individuals with BPD have a great deal of difficulty regulating emotions.

Now, that may sound very much like a feature of bipolar disorder—but there is a subtle difference in BPD. Whereas persons with bipolar disorder experience periods of abnormal mood, in which their mood state bears little or no relationship to what’s going on around them, persons with BPD have difficulty modulating what might be called normal moods. In BPD, a person’s emotional reactions to unpleasant situations come on more quickly, are more intense, and are slower to return to baseline. More importantly, these intense reactions characterize them all the time, not just during discreet episodes, so much so that they can be thought of as part of the individual’s make-up or temperament, which is why the term “personality disorder” is part of the terminology for this problem.

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Persons with BPD tend to react to situations with negative emotions like anxiety, depression, and anger more readily than others, to the point where even relatively neutral situations tend to be interpreted negatively and tend to provoke negative emotions. As a result, they are always battling an ever-present swirl of painful, uncomfortable emotions.

Persons with BPD are also less equipped to cope with these negative emotions. Their emotions change rapidly and unpredictably and easily spiral out of control, leading to extremes of anxiety, sadness, rage, or excitement. They can go from mildly irritated to utterly enraged in a heartbeat, or from feeling merely disappointed to suicidal just as quickly. They cannot talk themselves out of these spirals but tend to “catastrophize” immediately, imagining the worst-case scenario in every situation. When strong emotions are stirred up, they can even become irrational.

Borderline personality disorder is not easy to diagnose because persons who eventually get this diagnosis often have symptoms they share with other psychiatric problems (like mood disorders, anxiety disorders, addiction, and eating disorders). Only an experienced clinician can diagnose BPD and then only after getting to know the patient quite well.

Another difficulty with diagnosing BPD and differentiating it from bipolar disorder is that a person can have both. There is evidence that persons with BPD are especially likely also to have mood disorders, including bipolar disorder, often bipolar II or a “soft” bipolar disorder. What is the relationship between these two problems?

A group of psychiatrists at Harvard led by Dr. John Gunderson, who has studied borderline diagnosis for many years and is one of the leading experts in the disorder, attempted to answer this question by following 196 individuals who were carefully diagnosed by experts as having BPD, assessing them for a co-morbid diagnosis of bipolar I or II and then following them for four years, re-evaluating them annually to assess whether additional individuals had developed a bipolar disorder. The researchers found that almost one in five patients with a diagnosis of borderline personality either came into the study with bipolar disorder or developed it during the four years they were followed.

How can we synthesize these data? On the one hand, it has been proposed that BPD is just another form of bipolar disorder, a proposal that is almost certainly wrong. Nevertheless, there appears to be a connection between the two diagnoses. It may be that whatever genetic factors are that put a person at risk for developing BPD also put them at risk of developing bipolar disorder. One of my colleagues at Johns Hopkins, Dr. Dean MacKinnon, proposed an idea that I admire very much, which is that the symptoms and behaviors that characterize BPD result from an interaction between an individual’s biologically determined tendency to experience strong emotions and childhood experiences that are invalidating of those emotions. The idea is that the child’s extra-strong emotional reactions are ignored or discounted by their environment, leading the child to feel invalidated, damaged, and “different” and leading to the damaged sense of self and dysfunctional behaviors that are seen in BPD.

Both bipolar disorder and borderline personality disorder are eminently treatable and these patients can enjoy happy and productive lives with proper therapy. But getting the diagnosis right can be challenging.