White Matter Regional Volumes in Relation to Menstrual Cycle Phase and Premenstrual Dysphoric Disorder.

Background: Premenstrual dysphoric disorder (PMDD) is an understudied, debilitating, and hormone-related mental disorder. Recent evidence suggests alterations in white matter structure during the symptomatic luteal phase in PMDD. In this study, white matter volumes (WMVs) in the brains of women with PMDD versus control women were compared across the menstrual cycle, to determine whether these differences reflect state- or trait-like characteristics. Methods: Anatomical magnetic resonance imaging was performed during the midfollicular phase and the late luteal phase of the menstrual cycle in 28 women with PMDD and 27 control women. WMVs were assessed using voxel-based morphometry, employing both region-of-interest (ROI) and exploratory whole-brain approaches. Results: No group-by-phase interaction effects on WMVs were found. Across menstrual cycle phases, women with PMDD exhibited greater WMVs than control women within ROIs (in the bilateral uncinate fasciculus, right inferior fronto-occipital fasciculus, and left crus and fimbria of the fornix) and across the whole brain (in inferior occipital areas and near the angular gyrus), indicating trait- rather than state-like structural markers of PMDD. Conclusions: These findings suggest that women with PMDD exhibit larger WMVs than healthy control women, during both the symptomatic and asymptomatic phases of the menstrual cycle, in white matter tracts involved in emotion processing and regulation, memory, and connecting limbic and prefrontal regions of relevance to mood disorders.