Borderline personality disorder (BPD) and bipolar disorder frequently co-occur (numbers range from 8% to 18%), although they are distinct clinical entities (Paris J et al, Compr Psychiatry 2007;48(2):145–154). A proper diagnosis guides the most effective treatment, but you’ve probably faced the difficult challenge of diagnosing these conditions, which share several clinical features.
BPD can be described by four types of psychopathology: affective disturbance, impulsivity, cognitive problems, and intense, unstable relationships. What’s most important—in addition to seeing that your patient meets DSM-IV criteria for BPD—is to establish that patterns of affective instability, impulsivity, and unstable relationships have been consistent over time. Thus, obtaining a detailed history is crucial. Also, the key features we see in BPD, such as dissociation, paranoia, and cognitive problems, are often affected by the patient’s environment and, particularly, his or her relationships. A patient might have a history of rapid and sudden deterioration when relationships change—such as threatening suicide after a breakup or severe mood swings when separated from her family. Generally, the more intense or significant the relationship is, the greater the risk of chronic stress and mood dysregulation.
Many of the same features are seen in patients with bipolar disorder, such as dysphoria, hyperactivity, impulsivity, suicidality, and psychotic symptoms. As a result, borderline patients with this cluster of symptoms are often misdiagnosed with bipolar disorder, possibly because of the effectiveness of psychopharmacological treatments for such symptoms. In fact, a more thorough assessment might show that these patients actually suffer from a personality disorder. In one study, more than one third of those misdiagnosed with bipolar disorder met DSM-IV criteria for BPD (Zimmerman M et al, Compr Psychiatry 2010;51(2):99–105).
In BPD, mood changes are generally short-lived, lasting only for a few hours at a time. In contrast, mood changes in bipolar disorder tend to last for days or even weeks or months. Mood shifts in BPD are usually in reaction to an environmental stressor (such as an argument with a loved one or a frustration in the waiting room), whereas mood shifts in bipolar disorder may occur out of the blue. Some clinicians consider BPD an “ultrarapid-cycling” form of bipolar disorder, but there’s little evidence to support this link (Gunderson JG et al, Am J Psychiatry 2006;163(7):1173–1178). Patients with BPD might rapidly cycle through depression, anxiety, and anger, but these mood shifts rarely involve elation; more often, the mood shifts are from feeling upset to feeling just “OK.” Likewise, the anxiety or irritability of BPD should not be mistaken for the mania or hypomania of bipolar disorder, which usually involve expansive or elevated mood.
At a more existential level, patients with BPD—particularly younger patients— often struggle with feelings of emptiness and worthlessness, difficulties with self-image, and fears of abandonment. These are less common in bipolar disorder, where grandiosity and inflated self-esteem are common, especially during mood episodes. And while both conditions may include a history of chaotic relationships, a patient with BPD may describe relationship difficulties as the primary—or sole—source of her/his suffering, while the bipolar patient may see them as an unfortunate consequence of his behavior.
A pattern of self-harm and suicidality often serves as a cue for diagnosing BPD (but are not necessarily required). But both can be seen in bipolar disorder, too. In BPD, suicide threats and attempts may occur along with anger at perceived abandonment and disappointment. Patients often explain these impulses as a way to be relieved of pain, or to “stop their thinking,” more so than to end their lives, per se. Patients with BPD may experience “micropsychotic” phenomena of short duration (lasting hours or at most a few days), including auditory hallucinations, paranoia, and episodes of depersonalization. However, patients generally retain insight, and can acknowledge that “something strange is happening” without strong delusional thought. When psychotic symptoms occur in bipolar disorder, they happen in the context of a mood episode, they tend to last longer, and patients may be unable to reflect on their behavior.
Accurate diagnosis of BPD and bipolar disorder can be difficult, but it’s essential for proper treatment and optimal outcome. Remission rates in BPD can be as high as 85% in 10 years (Gunderson et al, Arch Gen Psychiatry 2011;68(8):827–837), particularly with effective psychotherapeutic treatments (Zanarini MC, Acta Psychiatr Scand 2009;120(5):373– 377). Unfortunately, such treatment is not always available. Some medications can be used in BPD, such as an SSRI for impulsivity, severe and persistent depression and/or suicidality, or an atypical antipsychotic for recurrent dissociative symptoms or disinhibition. However the only consensus seems to be that medications should be used as adjuncts to psychotherapy (Silk KR, J Psychiatric Practice 2011;17(5):311–319). The long-term use of a mood stabilizer or atypical should be reserved for known cases of bipolar disorder.
TCPR’s VERDICT: Clinicians sometimes think of a BPD diagnosis as pejorative (chronic and untreatable) and may be reluctant to disclose it, but patients and their families often find it helpful to be informed of the diagnosis. Similarly with bipolar disorder, accurate diagnosis often determines prognosis and effective treatment. For the clinician, however, it’s imperative that you make the proper diagnosis in these two often overlapping, but fundamentally quite distinct, conditions in order to optimize your patients’ outcomes.