Mono vs Combo Therapy in Bipolar Disorder

Authors Victoria E. Cosgrove, Santiago Allende, Iola Gwizdowski, E. Grace Fischer, Michael Ostacher, Trisha Suppes

Background: Many patients with bipolar I disorder do not respond to monotherapy treatment with mood-stabilizing medications, and combination regimens are commonly used in both inpatient and outpatient settings for the acute and maintenance treatment of bipolar disorder. We studied whether combination therapy is more effective than monotherapy for the acute treatment of subjects with bipolar I disorder currently experiencing manic symptoms. The primary hypothesis was that combination treatments would be associated with greater reductions in symptoms of mania and hypomania than monotherapy alone. The secondary hypothesis was that combination therapies would be associated with lower depression levels than monotherapy alone. Last, a post-hoc exploratory aim was used to examine whether the effect of side effect severity on risk-of-dropout would be greater in combination therapies than in monotherapy alone.

Methods: In this 12-week, double-blind, placebo-controlled ambulatory pilot trial, participants (n = 75) with bipolar I disorder were randomly assigned to: (1) monotherapy divalproex plus placebo (DVP + PBO), (2) combination therapy of divalproex plus blinded lithium (DVP + Li) or (3) divalproex plus blinded quetiapine (DVP + QTP). Combination therapies (vs. monotherapy) were not associated with improved symptoms of mania, hypomania or depression. The effect of side effect severity on study retention did not differ between combination therapies and monotherapy. However, the risk-of-dropout was significantly greater in the DVP + Li arm versus the DVP + PBO arm.

Results:. The two groups did not differ on indices of SIP or social skills over time. A three-way interaction between measures of SIP, group, and time predicted peer relationships. Survivors of pediatric solid tumors showed a positive association between baseline social skills and theory of mind and peer relationships over time, whereas survivors of pediatric brain tumors showed an inverse association between baseline social skills and theory of mind and peer relationships over time.

Conclusions:. No longitudinal differences in mania, hypomania or depression were found between combination therapies and monotherapy. The effect of side effect severity on study retention did not differ between groups. Due to the small sample size and differential rates of attrition between treatment arms, results of this pilot trial must be interpreted with caution.