Depression and anxiety disorders are prevalent mental illnesses, and their aetiology is intricate and remains incompletely elucidated. In recent years, researchers in both domestic and international settings have conducted a substantial amount of research on the pathological mechanisms and treatment methods of depression and anxiety disorders. This paper presents a summary of the pathogenesis of depression from the perspective of brain function and structure. It identifies abnormalities in brain regions, including the hippocampus and prefrontal lobe, as being closely related to the condition. These abnormalities are manifested in a reduction in cortical area and volume, as well as impairment of neuronal morphology and ultrastructure in these brain regions. Furthermore, patients with depression are frequently linked to diminished cerebral blood flow, reduced metabolism, aberrant brain network connections and an imbalance in neurophysiological activity. In contrast, patients with anxiety disorders display functional abnormalities in the amygdala, default mode network, cognitive control network and motivational network. These clinical studies have provided new ideas for treatment, and many of them have proposed innovative treatment concepts that are worthy of further investigation and application in clinical practice. This article provides a summary of the progress of research on the brain mechanisms of depression and anxiety disorders, with the aim of providing a reference for their diagnosis and treatment. Further in-depth study of brain function and structural abnormalities in these disorders may facilitate the development of more effective treatments, thereby improving the quality of life of patients.
