Objective: This study examined the long-term effectiveness of lithium for the treatment of pediatric bipolar disorder within the context of combination mood stabilizer therapy for refractory mania and pharmacological treatment of comorbid psychiatric conditions.

Methods: Outpatients, ages 7-17 years, meeting American Psychiatric Association, diagnostic and statistical manual of mental disorders, 4th ed. (DSM-IV) diagnostic criteria for bipolar disorder I (BP-I) (manic or mixed) who demonstrated at least a partial response to 8 weeks of open-label treatment with lithium (phase I) were eligible to receive open-label lithium for an additional 16 weeks (phase II). Up to two adjunctive medications could be prescribed to patients experiencing residual symptoms of mania or comorbid psychiatric conditions, following a standardized algorithm.

Results: Forty-one patients received continued open-label long-term treatment with lithium for a mean of 14.9 (3.0) weeks during phase II. The mean weight-adjusted total daily dose at end of phase II was 27.8 (6.7) mg/kg/day, with an average lithium concentration of 1.0 (0.3) mEq/L. Twenty-five of the 41 patients (60.9%) were prescribed adjunctive psychotropic medications for residual symptoms. The most frequent indications for adjunctive medications were refractory mania (n=13; 31.7%) and attention-deficit/hyperactivity disorder (ADHD) (n=15; 36.6%). At the end of this phase 28 (68.3%) patients met a priori criteria for response (≥50% reduction from phase I baseline in young mania rating scale [YMRS] summary score and a clinical global impressions-improvement [CGI-I] score of 1 or 2), with 22 (53.7%) considered to be in remission (YMRS summary score≤12 and CGI-severity score of 1 or 2). These data suggest that patients who initially responded to lithium maintained mood stabilization during continuation treatment, but partial responders did not experience further improvement during Phase II, despite the opportunity to receive adjunctive medications. The most commonly reported (≥20%) adverse events associated with lithium treatment were vomiting, headache, abdominal pain, and tremor.

Conclusions: Lithium may be a safe and effective longer-term treatment for patients with pediatric bipolar disorder who respond to acute treatment with lithium. Partial responders to acute lithium did not appear to experience substantial symptom improvement during the continuation phase, despite the possibility that adjunctive medications could be prescribed.