Exploring the clinical characteristics and etiological factors of comorbid major depressive disorder and social anxiety disorder

The comorbidity between the major depressive disorder (MDD) and the social anxiety disorder (SAD) is significantly prevalent, necessitating a nuanced understanding of their overlapping clinical characteristics and shared etiological factors, including inflammatory biomarkers. To address this, we conducted a cross-sectional study from December 2021 to June 2022, encompassing 204 outpatients diagnosed with MDD–SAD comorbidity. We employed various psychometric assessments, such as the Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), Childhood Trauma Questionnaire (CTQ-28), Toronto Alexithymia Scale (TAS-20), and the Liebowitz Social Anxiety Scale (LSAS). Additionally, we analyzed inflammatory biomarkers, including the neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), neutrophil-to-lymphocyte platelet ratio (NLPR), systemic inflammation index (SII), and the systemic inflammation response index (SIRI). Our findings accentuated that patients primarily diagnosed with MDD exhibited elevated levels of certain inflammatory biomarkers. They reported more severe and atypical depressive symptoms (75.7% vs 58.5%; P ═ 0.010) and had significantly higher CTQ-28 subscale scores (P < 0.05). Our study unveils a complex relationship between MDD and SAD, with significant disparities in the symptom severity and inflammatory biomarker levels, thereby establishing a compelling case for dual-diagnosis treatment approaches. It elucidates the critical role of inflammation in the comorbidity of MDD and SAD, marking a pioneering step towards more comprehensive and holistic patient care strategies. These insights could potentially revolutionize therapeutic approaches in psychiatric care, promising significantly improved outcomes through early detection and integrated intervention strategies.