Neuroimaging progesterone receptor modulation in patients with premenstrual dysphoric disorder : Is it just in your head?

Abstract: Premenstrual dysphoric disorder (PMDD) is a menstrually related mood disorder affecting about 5% of women during their reproductive years. The disorder is cyclic, with the symptomatology namely occurring at the luteal phase of a menstrual cycle, for most ovulatory menstrual cycles and entails a series of mood and physical symptoms. A neural susceptibility to regular hormonal fluctuations is hypothesized as the neuropathophysiological mechanism. While treatment options, such as selective serotonin reuptake inhibitors and hormonal interventions, are available, the neural mechanisms underlying symptom relief remain largely unclear. In this series of studies, a multimodal neuroimaging design was approach was used to reveal the neural correlates of three-month, low-dose selective progesterone receptor modulator (SPRM) treatment in comparison to a placebo. This treatment has been demonstrated to be effective in alleviating psychological symptoms associated with PMDD. Thirty-five women with fulfilling the criteria of a PMDD diagnosis were randomized to treatment with SPRM or placebo, with structural and functional MRI scans conducted before and after randomization. Findings indicated enhanced fronto-cingulate activity during a reactive aggression task in the SPRM treatment group compared to placebo, along with a negative association between aggressive responding and brain activity in the placebo group. Resting state functional connectivity was additionally altered after treatment with SPRM in fronto-visual, temporo-insular, and temporo-cerebellar regions. Additionally, a positive correlation was observed between the reduction in cortisol levels and the decrease in temporo-insular connectivity. No treatment effects were observed on brain structure, including grey and white matter volume, as well as cortical surface architecture. Lastly, White matter microstructure integrity did not differ longitudinally but showed cross-sectional differences. In conclusion, the effects of SPRM treatment were primarily observed in brain function, specifically in terms of enhanced cognitive control processing in the context of reactive aggression and resting state functional connectivity in regions relevant to cognitive and sensorimotor processing, with no significant structural alterations noted. Taken together, these findings confirm that the fluctuations rather than absolute levels of ovarian hormones are primary contributing to premenstrual symptomatology, potentially through hormonal-state dependent functional correlates.