Lithium increases cortical and subcortical volumes in subjects with bipolar disorder

•Gray and white matter volumetric increases can be seen after only six weeks of lithium monotherapy.•Such improvements can be seen in younger, less severe patients and a low serum lithium concentration.•Despite clinical shifts towards second-generation antipsychotics as first line mood stabilizers, expanding the use of lithium into demographics represented in this study may have underappreciated benefits in long-term neuronal preservation.