Brain-derived neurotrophic factor (BDNF) is a crucial growth factor in the central nervous system (CNS), essential for neuronal development and plasticity. This review explores the role of BDNF in various neuropsychiatric disorders, including major depressive disorder (MDD), schizophrenia, addiction, and mood disorders. BDNF signaling through tropomyosin-related kinase B receptors (TrkB) is key to its functions, involving multiple intracellular signaling pathways such as PLC γ, PI3K, and MAPK/ERK. BDNF is involved in axonal growth, synaptic plasticity, and learning and memory processes. In MDD, BDNF expression is reduced by stress and increased by antidepressant treatment, suggesting its potential as a biomarker and therapeutic target. Animal models of depression, such as chronic stress, show decreased BDNF levels, and BDNF infusion can produce antidepressant-like behaviors. BDNF also interacts with the serotonergic system, and its regulation by antidepressants may explain their efficacy. In bipolar disorder, BDNF expression is altered, and the V66M polymorphism is strongly correlated with the disorder. In anxiety-related disorders, BDNF may affect anxiety levels, but the neural circuits involved are not fully understood. In schizophrenia, BDNF levels are varied across studies, and animal models of the disease show altered BDNF expression. Overall, BDNF plays a significant role in neuropsychiatric disorders and its manipulation may offer therapeutic opportunities.Brain-derived neurotrophic factor (BDNF) is a crucial growth factor in the central nervous system (CNS), essential for neuronal development and plasticity. This review explores the role of BDNF in various neuropsychiatric disorders, including major depressive disorder (MDD), schizophrenia, addiction, and mood disorders. BDNF signaling through tropomyosin-related kinase B receptors (TrkB) is key to its functions, involving multiple intracellular signaling pathways such as PLC γ, PI3K, and MAPK/ERK. BDNF is involved in axonal growth, synaptic plasticity, and learning and memory processes. In MDD, BDNF expression is reduced by stress and increased by antidepressant treatment, suggesting its potential as a biomarker and therapeutic target. Animal models of depression, such as chronic stress, show decreased BDNF levels, and BDNF infusion can produce antidepressant-like behaviors. BDNF also interacts with the serotonergic system, and its regulation by antidepressants may explain their efficacy. In bipolar disorder, BDNF expression is altered, and the V66M polymorphism is strongly correlated with the disorder. In anxiety-related disorders, BDNF may affect anxiety levels, but the neural circuits involved are not fully understood. In schizophrenia, BDNF levels are varied across studies, and animal models of the disease show altered BDNF expression. Overall, BDNF plays a significant role in neuropsychiatric disorders and its manipulation may offer therapeutic opportunities.