The Underlying Mechanisms of Comorbid Anxiety and Depression Among Young Women: Evidence From Brain Structure and Hormone

Aim: Youth is a time of a significant rise in depressive symptoms, particularly impacted by anxiety in females. However, the identification of the transition from anxiety to depression in young women remains ambiguous. This study collects data on brain structure and hormone levels in young women, intending to investigate the neurophysiological differences among women with anxiety disorders and comorbid anxiety and depression (CAD). Methods: 53 young women were divided into three groups, namely an anxiety group, a CAD group, and a control group, aiming to explore the differences in brain structure and ovarian hormone levels. Results: The CAD group exhibited significantly reduced gray matter volume (GMV) in the right superior frontal gyrus (SFG; 0.38 ± 0.05) and right middle occipital gyrus (MOG; 0.37 ± 0.04) compared to the anxiety (SFG: 0.41 ± 0.04; MOG: 0.41 ± 0.04) and control groups (SFG: 0.45 ± 0.04; MOG: 0.44 ± 0.03; all p   < 0.001). Cortical thickness in the right SFG was also significantly lower in the CAD group (2.81 ± 0.24) than in the anxiety (3.08 ± 0.21) and control groups (3.11 ± 0.19; p   < 0.001). Progesterone was negatively correlated with GMV in the right MOG ( r  = −0.48, p = 0.042) and SFG ( r  = −0.53, p = 0.020) only in the CAD group. Further, no significant associations were observed between estradiol levels and brain structure, nor between anxiety/depression scores and hormone or brain data (all p   > 0.070). Conclusions: The change of brain structure in the SFG and MOG may be one of the mechanisms underlying the progression of symptoms from anxiety to CAD, which may also be related to the increase in progesterone, indicating the exacerbation of emotional disorders in young women.