Lithium treatment effects on myo-inositol in adolescents with bipolar depression

Background: The neurochemical effects of lithium in adolescents with bipolar disorder largely are unknown. This study used proton magnetic resonance spectroscopy (H-1 MRS) to identify the in vivo effects of lithium on myo-inositol (mI) concentrations in adolescent bipolar depression. Methods: Twenty-eight adolescents (12-18 years old) with bipolar I disorder, current episode depressed, received open-label lithium 30 mg/kg, adjusted to achieve serum levels of 1.0-1.2 mEq/L. The mI concentrations in the medial as well as the left and right lateral Prefrontal cortices were measured at baseline, day 7, and day 42 of treatment. Changes in mI concentrations over time were analyzed. Results: Significant main effects of time were observed for mI concentrations in the medial (p =.03) and tight lateral (p =.05) prefrontal cortices. Baseline concentrations of mI were not significantly different from day 7 or day 42 concentrations. However, mI concentrations on day 42 were significantly higher than those on day 7 (p =.02) in both regions. Conclusions: This study demonstrates that prefrontal mI concentrations do not significantly change from baseline after acute and chronic lithium treatment in adolescents with bipolar depression. Further investigation of the effect of lithium on mI is warranted to better understand possible mechanisms by which lithium exerts antidepressant activity.