Impact of Psychotherapy on Occupational Functioning for Individuals with Bipolar II Depression at Different Stages of Illness Progression?

Background and Purpose: Bipolar disorders (BD) are the sixth leading cause of disability worldwide and individuals with bipolar II disorder (BD II) frequently demonstrate severe occupational functioning even during times of wellness. Subsequently, individuals with BD II report a profound impact of their illness on their quality of life. The staging model of BDs 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 BD II and in understanding how stage of illness progression impacts functional recovery. This study investigated whether individuals with BD II depression experienced differential improvement in occupational functioning when receiving medication in addition to psychotherapy compared to psychotherapy and placebo, and whether stage of illness progression predicted occupational functioning outcomes.

Methods: The sample consisted of individuals meeting DSM-IV criteria for BD II, 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. Fully Bayesian model based imputation was used to perform an intent to treat analysis consisting of multilevel modeling with growth modeling.

Results: The majority of participants were impaired in their occupational functioning at baseline (77%) without a significant difference in impairment between treatment groups (p = 0.467). Results demonstrate improvement in occupational functioning (F_1,2152.8 = 5.18, P=0.023), without a significant difference between those receiving IPSRT+P and IPSRT+Q (P > 0.05). Yet, the majority of participants remained impaired in their occupational functioning (62%). For every additional week of treatment there was a 0.061 (SD = 0.027) decrease in FAST occupational functioning score (t = -2.28, P = 0.023, CI = -0.113 – -0.008). The time by group interaction was not significant and the individual trajectories of the treatment groups did not significantly differ (P = 0.331). 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.

Conclusions and Implications: Individuals receiving IPSRT plus placebo had comparable improvement in occupational functioning to those receiving IPSRT plus quetiapine. However, the majority of participants remained impaired in occupational functioning. Individuals in later stage of illness progression had worse occupational functioning scores at baseline, but showed more improvement in occupational functioning than those in earlier stages of illness progression. Therefore, psychotherapy alone may be a reasonable treatment option for individuals with BD II regardless of stage of illness progression to improve functioning, but longer maintenance treatment may be needed to regain full functioning. Study limitations include absence of an inactive comparator group, a medication only treatment group, small sample size, lack of diversity, and high dropout.