Reduced myelin density in unmedicated major depressive disorder: An inhomogeneous magnetization transfer MRI study

•This was the first time to utilize ihMT technique to evaluate the integrity of the WM myelin in unmedicated non-late-life adult patients with MDD without the potentially confounding influence of psychotropic medications and aging.•We found decreased qihMT and ihMTR values in the left IFOF and the left UF in MDD.•Disrupted integrity of the myelin may be a key neurobiological feature of MDD.•ihMT technique could explore myelin integrity on the macromolecular level.