Grey matter structural asymmetry and premenstrual dysphoric disorder.

INTRODUCTION: Left-right brain asymmetry is an important feature of human neuroanatomy, with implications for cognition, behaviour, and vulnerability to mental disorders. Despite evidence for lateralized sensitivity to hormonal fluctuations, the cortical and subcortical asymmetry profile of individuals with premenstrual dysphoric disorder (PMDD), a hormone-related mood disorder associated with alterations in brain structure, remains unexplored. METHODS: In this study, a total of 68 females with PMDD and 51 healthy females underwent magnetic resonance imaging (MRI) during the luteal phase of the menstrual cycle. Structural asymmetry was assessed using voxel-wise whole-brain analysis and region of interest (ROI) approaches for grey matter volume (GMV), as well as ROI-based analysis of cortical thickness. Associations between asymmetry and symptom severity were also investigated. RESULTS: Whole-brain analyses revealed significantly greater leftward GMV asymmetry in PMDD participants in two clusters within the anterior fusiform gyrus and the anterior insula. ROI-based analyses did not show any asymmetry group differences in either GMV or cortical thickness. Within the PMDD group, greater leftward asymmetry in the amygdala GMV was moderately associated with higher irritability. CONCLUSION: These findings provide novel, region-specific evidence for structural asymmetry in PMDD and suggest that lateralized brain architecture may contribute to affective symptom expression in this disorder.