(WITHDRAWN) Individuals with Bipolar II Depression: Does Stage of Illness Progression Predict Functional Outcomes?

Background/Purpose: Staging model of bipolar disorders (BD) postulates that with greater chronicity of mood episodes, more intensive treatments and combination strategies are needed to achieve the same treatment response. However the staging model is under researched, especially in bipolar II disorder (BDII) and in understanding how stage of illness progression impacts functional recovery. Further, few studies have examined specific domains of functioning (i.e. autonomy, occupational functioning, cognitive functioning, financial issues, interpersonal relationships, and leisure time) as outcomes in psychotherapy research of BD, with the majority of studies that examined this variable focusing on global functioning. This study investigates whether individuals with BDII depression experience differential improvement in specific domains of functioning when receiving medication in addition to psychotherapy. It examines whether stage of illness progression predicts functional outcomes.

Methods: Fully Bayesian model based imputation was used to perform an intent to treat analysis. Multilevel modeling with growth curve modeling was used to examine a sample of adults meeting DSM IV criteria for BDII, currently depressed (n=92) randomly assigned to receive interpersonal and social rhythm therapy (IPSRT) plus placebo or IPSRT plus quetiapine and treated for 20 weeks. The Functional Assessment Short Test (FAST), an interview-based measure of functional impairment was administered at weeks one, eight, 12, and 20-week follow up by raters blind to treatment assignment.

Results: Results demonstrate improvement in functioning on all subscales [autonomy (F_1,1529.6 = 6.89, P = 0.009), occupational (F_1,2152.8 = 5.18, P = 0.023), cognitive (F_{1, .} = 29.29, P = 0.000), financial (F_{1, .} = 30.29, P = 0.000), interpersonal (F_1,1112.4 = 38.90, P = 0.000), and leisure (F_1,4273.4 = 30.08, P = 0.000)] without a significant difference between those receiving IPSRT+placebo and IPSRT+quetiapine (P > 0.05). Individuals with “too many depressive episodes too count” had worse occupational functioning at baseline (SD = 0.998) t = 3.44, P = 0.001, CI = 1.476 – 5.389), but showed more improvement (F_7,24165.1= 3.15, p = 0.003) than those with fewer previous depressive episodes.

Conclusion/Implications: Although psychosocial functioning is impaired in the majority of individuals with BDII, individuals improved in all domains of functioning regardless of whether they received medication in addition to IPSRT. Therefore, psychotherapy alone may be a reasonable treatment option for BDII depression to address impaired functioning especially for those who prefer it and those for whom medication is contraindicated. More research is needed to understand if IPSRT is associated with superior functional outcomes relative to other psychotherapies. Individuals with BDII depression in later stages of illness progression began with worse occupational functioning, but showed greater improvement compared to those in earlier stages of their illness. IPSRT with its emphasis on interpersonal, role functioning, and regularity of social rhythms/routines may have greater capacity to improve occupational functioning for individuals in later stages of illness progression. These findings merit further investigation and are in need of replication to inform treatment recommendations for individualized treatment planning for individuals with BDII. Study limitations include absence of an inactive comparator group, small sample size, and high dropout rates.