Differentiating BPD from bipolar disorder has ramifications for treatment planning, both pharmacological and psychosocial.
While randomized clinical trials of patients with BPD have been performed using mood stabilizers, antidepressants, and typical and atypical antipsychotics, their effect sizes have not been particularly robust. This, coupled with small sample sizes, prompted the recent Cochrane review to state that there are “insufficient data” to support any recommendations for pharmacological treatment in BPD. The report concluded that medication effects in BPD are “unimpressive.”37 Despite this, although not empirically validated, study findings suggest that polypharmacy for BPD is rampant, and it is not uncommon for patients with BPD to be treated with multiple agents.38 This can result in significant iatrogenic morbidity that may outweigh the marginal clinical benefits. In contrast, pharmacological treatment in bipolar disorder is far more effective. Eleven drugs are FDA-approved for the treatment of bipolar disorder: 9 for mania/mixed phases, 2 for depressive phases, and 5 for maintenance therapy (several are approved for more than one phase of the illness).
Although similar medications are used for both BPD and bipolar disorder, the clinical effectiveness of the medications and target symptoms of the disorders differ. In bipolar I disorder patients, mood stabilizers are the first line of treatment. In BPD, randomized controlled trials of valproate(Drug information on valproate) and carbamazepine(Drug information on carbamazepine) have targeted impulsivity and anger rather than affective instability, while a randomized controlled trial of lithium showed no benefit at all.39-42 Similarly, randomized controlled trials of newer mood stabilizers such as topiramate(Drug information on topiramate) and lamotrigine(Drug information on lamotrigine) have been shown to target anger rather than affective instability.43,44
A positive clinical response has been found for antidepressants of several classes including monoamine oxidase inhibitors and SSRIs, for both the depressed phase of bipolar disorder and for BPD. The propensity of antidepressants to produce manic symptoms in patients with bipolar disorder is always a consideration despite controversy about the magnitude or clinical importance of the risk, but this does not seem to be the case for BPD. SSRIs in BPD appear to target anger and impulsivity, rather than mood symptoms; a similar finding was noted by Paris19 in a study of atypical antipsychotics for both BPD and bipolar disorder.
The findings on medication treatment in patients with BPD suggest that an over-reliance on psychopharmacological strategies yields disappointing results. Medication efficacy is far more pronounced in patients with bipolar disorder.33,45 The Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD), a longitudinal study of 4107 persons with bipolar disorder that evaluated treatment effectiveness, has generated valuable data on head-to-head medication trials and will continue to provide insights into optimal treatment strategies for the various phases of bipolar disorder.46
Table 2 presents psychosocial treatments available to patients with bipolar disorder or BPD. Despite symptomatic overlap, the types of interventions differ by disorder.
In contrast to the meager efficacy of pharmacological treatment for BPD, psychosocial treatments have shown substantial promise and many psychotherapeutic interventions that focus on teaching emotion-regulation skills exist. These include:
• Dialectical behavior therapy47
• Systems training for emotional predictability and problem solving (STEPPS)48
• Schema-focused therapy49
• Mentalization-based treatment50
• Transference-focused psychotherapy51
Psychoeducation has been identified as an inte-gral component in the treatment of BPD, and it has been usefully extended to family members as well.52,53
In bipolar disorder, the value of psychosocial interventions is gaining recognition as an important adjuvant treatment. The therapeutic aims of psychosocial approaches for bipolar disorder include psychoeducation, stress management, and regularity in daily activitiesand biosocial rhythms.54-57
John is a 50-year-old, white, never-married man who initially presented with irritability and depression. He denied any current or past suicidal or homicidal ideation but endorsed a past history of “mood swings.” He had been given a diagnosis of bipolar II disorder 10 years earlier. John described his moods as never vacillating to periods of elation but rather as centered on feelings of hostility and anger. He had a 20-year history of heavy alcohol(Drug information on alcohol) use and reported that he had completed a court-mandated alcohol rehabilitation program several years earlier.
Over the next few sessions, his preoccupation with his partner’s fidelity and whereabouts, his dependency on others, identity confusion, and impulsivity manifested themselves. He had rapid mood shifts in session, particularly when the discussion centered on his current romantic relationship of 5 months. Given the quality of his mood swings and associated symptoms, BPD was diagnosed and John was referred for medication management and dialectical behavior therapy.
As noted by Gunderson and colleagues,9 and as exemplified by this case, persons with BPD often receive a diagnosis of bipolar spectrum disorder. The failure to appreciate the BPD diagnosis, whether from misdiagnosis or a hesitancy to offer a stigmatizing label, can affect treatment outcome. As previously discussed, the effects can range from overuse of medication and potential polypharmacy to an underappreciation of empirically validated psychological treatments of BPD.
BPD and bipolar disorder are both associated with significant levels of mortality and morbidity, and they present diagnostic challenges because of their phenotypic overlap. However, paying attention to the patient’s quality of mood shifts, types of impulsivity, and longitudinal course may aid in distinguishing between the 2 disorders. Accurate diagnosis is important because each disorder has a distinct medication response and set of psychosocial interventions. The possibility of comorbid presentation also requires consideration because this may have an impact on the risk of self-damaging behaviors.