Psychotherapy as monotherapy for the treatment of bipolar II depression: a proof of concept study

Bipolar II disorder (BPII) is a common psychiatric illness with a reported lifetime prevalence of 0.5–11% (1–3). Characterized by multiple, protracted depressive episodes and mixed mood states, evidence suggests that BPII is at least as disabling as bipolar I disorder (BPI). In contrast to individuals with BPI, individuals with BPII may experience higher rates of rapid cycling, shorter ‘well’ periods, and greater impairment from subthreshold symptoms (4–8). Despite the fact that this is a prevalent condition associated with marked morbidity and impairment, few treatments for this disorder have been systematically evaluated (9). The specific role of psychotherapy in the management of individuals suffering from BPII is unknown. To our knowledge, there are no published trials of psychotherapy specifically for the treatment of BPII—with or without medication. Recently published data showed the addition of any of three intensive psychosocial interventions [Interpersonal and Social Rhythm Therapy (IPSRT), family-focused therapy, or cognitive behavioral therapy] to pharmacotherapy offered advantages in time-to-recovery relative to a control condition in a group of depressed subjects meeting criteria for both BPI and BPII, although investigators did not examine separate outcomes in the subgroup meeting criteria for BPII (10). Similarly, the addition of care management interventions (with psychosocial components) to usual care (including pharmacotherapy) in mixed BPI and BPII populations resulted in improved long-term outcomes relative to usual care in managed care and Veterans Affairs settings, respectively (11–13). Although these trials demonstrate that there are advantages to adding psychotherapy to pharmacotherapy in pooled groups of subjects with both BPI and BPII diagnoses, they do not provide information on the feasibility of using psychotherapy as monotherapy for the treatment of BPII. This lacuna in the evidence base is notable for several reasons. Firstly, BPII exists phenotypically on a continuum of affective disorders between unipolar and bipolar I disorders. As several psychotherapies have demonstrated efficacy as monotherapy for unipolar depression (14), it raises the possibility that at least a subset of individuals with this disorder may also respond to psychotherapy alone. Secondly, individuals suffering from BPII struggle with many issues that would be appropriately addressed by psychotherapy, such as declines in interpersonal and vocational functioning because of chronic untreated symptoms, difficulty distinguishing among mood states, including inability to recognize hypomania (15), and skepticism about working with a medical establishment that has repeatedly failed to recognize their illness (16) and has little to offer them in the way of informed treatment options (9, 17). Finally, all currently available pharmacotherapy for bipolar spectrum disorder is associated with problematic side effects (18), raising the possibility that those who do not tolerate medications will benefit from psychotherapy alone. It is therefore surprising that psychosocial interventions for BPII have received so little research attention. The goal of this study was to demonstrate the feasibility of using an empirically tested psychotherapy for bipolar disorder, IPSRT (19), as a treatment for unmedicated individuals meeting criteria for BPII, currently depressed. IPSRT is based on the principles of interpersonal psychotherapy for unipolar depression (20) and the demonstrated relationship between mood episodes and life events (21). It addresses patients’ sleep/wake cycles and levels of activation, thereby directly targeting the underlying circadian rhythm perturbations associated with bipolar disorder (22). It has now been shown to be efficacious when used with pharmacotherapy for the treatment of acute bipolar depression (10) and in the prevention of recurrence in patients with BPI (23). This was considered a proof of concept study in that, to our knowledge, there are no prior reports of psychotherapy as monotherapy for the management of acute bipolar II depression. The modest goals of a proof of concept study include demonstration of feasibility and establishment of directions for future research.