Neuroimaging in Psychiatric Disorders

Abstract

Advanced neuroimaging methods have greatly expanded our understanding of psychiatric disorders by enabling detailed evaluation of brain structure, function, and connectivity. This review synthesizes findings from major psychiatric conditions, including schizophrenia, major depressive disorder, bipolar disorder, obsessive–compulsive disorder (OCD), anxiety disorders, autism spectrum disorder, and attention-deficit/hyperactivity disorder (ADHD). Across disorders, structural mahnetic resonance imaging (MRI) consistently reveals cortical and subcortical abnormalities, while diffusion tensor imaging highlights widespread white-matter dysconnectivity. Functional MRI studies demonstrate disorder specific but overlapping alterations in network activity, particularly involving prefrontal, limbic, and default mode systems. Molecular and spectroscopic imaging add complementary insights into neurotransmitter and metabolic disturbances, including dopaminergic dysfunction in schizophrenia, glutamatergic abnormalities in mood disorders and OCD, GABAergic deficits in anxiety, and excitatory–inhibitory imbalance in autism and ADHD. Although no single imaging marker has sufficient specificity for clinical diagnosis, neuroimaging has substantially advanced mechanistic models of psychiatric illness. Longitudinal and multimodal approaches reveal developmental trajectories, illness progression, and treatment effects, such as lithium-related neurotrophic changes in bipolar disorder or normalization of hyperactive circuits following cognitive behavioral therapy (CBT) in OCD and anxiety disorders. Neuroimaging has transformed the conceptualization of psychiatric disorders from region-specific abnormalities to distributed network and molecular dysfunction. While still largely confined to research, ongoing advances in multimodal integration, large-scale collaborations, and precision imaging approaches hold promise for earlier detection, individualized intervention, and improved patient outcomes.