Throughout her hospitalization she denies that she attempted suicide that day, and maintains that this incident was caused by unintentional mismanagement of her medications. Although she continues to have a sense of low self-worth, she denies feeling depressed; in contrast, she says she feels like she has a “new lease on life.” During several interviews she cannot provide a history of any prolonged (ie, several days) episodes of elevated mood, increased goal-directed behavior, decreased need for sleep, tangential thought, pressured speech, or other symptoms that suggest hypomania or mania. She does not endorse prolonged periods of neurovegetative symptoms that would indicate a major depressive episode.
We feel that Ms. S’ symptoms of affective dysregulation, impulsivity, and interpersonal dysfunction are consistent with BPD, and we determine that she meets 6 of the 9 DSM-IV-TR diagnostic features of BPD (≥5 are required for a BPD diagnosis) (Table 1).7 Ms. S describes efforts to avoid abandonment, unstable and intense interpersonal relationships, marked and persistent unstable self-image, recurrent suicidal and self-mutilating behavior, affective instability, and chronic feelings of emptiness. She is discharged to follow up with a psychotherapist and family practitioner. She is not continued on any psychotropic medications.
The authors’ observations
Although it can be difficult to accurately diagnose psychiatric illness during a brief inpatient hospitalization, several clinicians who cared for Ms. S felt that her presentation was more consistent with BPD than BD. Her case is an example of the potential harm of incorrectly diagnosing personality-disordered patients with BD. Ms. S is impulsive and used lithium—a medication that is the standard of care for BD—in an overdose, which lead to a costly and dangerous hospitalization marked by a difficult tracheal intubation and hemodialysis.
Table 1
DSM-IV-TR diagnostic criteria for borderline personality disorder
| A pervasive pattern of instability of interpersonal relationships, self-image, and affects, and marked impulsivity, as indicated by ≥5 of the following: |
|
| Source: Reference 7 |
Distinguishing BD and BPD
There is considerable overlap in symptoms of BD and BPD. Although the episodic nature of BD is well differentiated from the more chronic course of BPD, many hypomania and mania symptoms are similar to those of BPD (Table 2).7 For example, patients with BD or BPD may exhibit impulsive behavior and labile moods. Substance use, risky and self-destructive behaviors, and inflammatory interpersonal relationships can occur in both disorders. Some researchers have suggested that pathophysiologically, BPD may fall on a spectrum of bipolar illness, and have proposed a clinical entity they call bipolar type IV or ultra-rapid cycling BD.2,8,9 There may be more co-occurrence of BD with BPD than would be expected by chance10; 1 review of BPD studies found the rate of comorbid BD ranged from 5.6% to 19%.11 However, because of differences in several factors—including phenomenology, family prevalence, longitudinal course, and medication response—some researchers have concluded that evidence does not support categorizing BPD as part of a bipolar spectrum.10-14 Nonetheless, BPD and other personality disorders often co-occur with axis I disorders, including MDD, BD, or PTSD.
Some research has suggested that the increasing availability and marketing campaigns of medications to treat BD may promote diagnosis of the disorder.15 Zimmerman15 hypothesizes that physicians may be more likely to diagnose a condition that responds to medication (ie, BD) than one that is less responsive (ie, BPD). Financial compensation for treating axis I disorders is significantly better than for treating personality disorders.16 The inpatient setting confers barriers to accurately diagnosing personality disorders, including limits on the amount of time that clinicians can spend with patients or ability to communicate with sources of collateral information. A patient’s observed personality and behaviors while hospitalized may not accurately reflect his or her personality and behaviors in that patient’s “natural” environment.