White matter microstructural properties in bipolar disorder in relationship to the spatial distribution of lithium in the brain

•Using a novel analysis, we combined diffusion tensor imaging and 7Li magnetic resonance imaging to investigate the effects of lithium in bipolar disorder (BD).•White matter gFA values were higher in those taking lithium compared to other medications, suggesting that lithium is associated with greater white matter integrity.•We report a positive association between white matter gFA and the spatial distribution of lithium in the brain.