Early improvement with lithium in classic mania and its association with later response

Despite lithium's clinical efficacy in treating mania in bipolar disorder (BD), studies evaluating early improvement and subsequent treatment response are sparse. This study investigated whether early improvement (within one week) to lithium monotherapy predicted later response and remission in individuals with BD mania.

BD-I patients (n=46) experiencing a manic episode received lithium monotherapy for four weeks (initial dose: 600mg/d, adjusted to therapeutic levels); individuals experiencing a mixed episode, rapid cyclers, previous non-responders to lithium, and those with current drug abuse/dependence were excluded. Symptoms were rated using the Young Mania Rating Scale (YMRS) at baseline and at Days 7, 14, 21, and 28.

Thirty-three percent of the total sample responded to lithium within the first week of treatment, defined as a ≥50% decrease from baseline YMRS scores; 63% responded by study endpoint. In addition, 39% of the total sample showed early improvement (at least 20% decrease in YMRS scores) after one week of treatment. In this group, 79% responded to lithium by study endpoint. Among those showing less than 20% improvement at Week 1, only 23% responded to lithium by study endpoint.

History of episodes sequence was not assessed.

Early improvement in response to lithium monotherapy in subjects with BD mania predicted later response and remission. Most patients who did not show early improvement in response to lithium during the first week of treatment showed no response after one month. The findings provide a valuable clinical tool for early identification of those patients most likely to benefit from lithium in clinical practice.