Abstract
Major depressive disorder (MDD) is a prevalent psychiatric disorder with a complex pathogenesis influenced by various factors. Recent research has highlighted a significant connection between psychological stress and MDD, with inflammation playing a central role in this relationship. Studies have demonstrated that peripheral immune changes in patients with MDD and in mouse models of social stress are closely linked to depressive symptoms. These findings suggest that targeting peripheral immune factors could represent a novel approach for treating stress-related neuropsychiatric disorders. Stress triggers a cascade of inflammatory responses, leading to disruptions in neurotransmitter metabolism and reduced synaptic plasticity. These changes exacerbate depression and contribute to cognitive decline. This study examines the bidirectional relationship between MDD and stress, focusing on the role of inflammation in this complex interplay. Recent studies have identified specific immune factors that are elevated in the serum of patients with MDD and stress-exposed mice, indicating a mechanism by which peripheral immune responses can affect central nervous system function and behavior. Furthermore, proteins, such as nuclear factor kappa-B (NF-κB), reportedly play a critical role in the regulation of stress hormones and are associated with depressive behaviors. Understanding these mechanisms is essential for advancing diagnostic, intervention, and treatment strategies for MDD.