Eight weeks of bright light therapy increases myelin density in the posterior thalamic radiation in young adults with subthreshold depression

Motivation: Subthreshold depression (SD) is a significant risk indicator of major depressive episodes. The inhomogeneous magnetization transfer (ihMT) technique has not been used to probe myelin abnormalities and its response to bright light therapy (BLT) in SD. Goal(s): In this study, we used ihMT technique to investigate myelin integrity in a relatively large sample size of university students with SD. Approach: The qihMT and ihMTR values of 50 white matter (WM) fibers were compared between SD and HCs. Results: Macromolecular disruption of myelin in the posterior thalamic radiation (PTR), sagittal stratum, and uncinate fasciculus might exist in the early stages of depression. Impact: These findings suggest the myelin impairments in the posterior thalamic radiation could be reversed by bright light therapy, which might be used as the potential neural target for bright light therapy in subthreshold depression.