Grey matter morphology in women with premenstrual dysphoric disorder treated with a selective progesterone receptor modulator.

Premenstrual dysphoric disorder (PMDD) is characterized by severe cyclic mood symptoms emerging in the luteal phase of the menstrual cycle. The variation in progesterone levels and its metabolites during the luteal phase seems critical to the occurrence of PMDD symptoms. Notably, the efficacy of selective progesterone receptor modulator (SPRM) treatment on the mental symptoms of PMDD has been recently demonstrated. In the present study, structural magnetic resonance imaging was used to assess the effects of SPRM treatment, compared with placebo, on grey matter morphology in women with PMDD. In total, 35 women were scanned during the luteal phase, before and after three months of treatment with SPRM or placebo. Symptom severity was assessed using the Daily Record of Severity of Problems (DRSP), while gonadal hormone levels were measured by liquid chromatography-tandem mass spectrometry. Region-of-interest and whole-brain approaches were employed to perform voxel-based morphometry analyses, subcortical volumetric analyses, and surface-based morphometry analyses. No interaction or main effects of treatment and time were observed on grey matter volume and cortical surface measures (cortical thickness, gyrification index, sulcal depth, and fractal dimension). The relationship between change in brain morphology and symptom severity was also explored but no treatment-dependant grey matter structure change was related to symptom severity change. These findings suggest that SPRM treatment does not impart macrostructural changes onto grey matter structure, at least in the short term.