Application of Neuroimaging Methods to Discover Neurobiological Biomarkers of Obsessive–Compulsive Disorder and to Analyze Related Cognitive–Neural Mechanisms

Abstract

Obsessive–compulsive disorder (OCD) is one of the most complex and disabling psychiatric disorders, characterized by heterogeneous clinical features, a chronic course, and relative resistance to conventional treatments. Recent advances in cognitive neuroscience and neuroimaging have opened new horizons for identifying biological markers associated with this disorder. The use of techniques such as functional magnetic resonance imaging (fMRI), diffusion tensor imaging (DTI), proton magnetic resonance spectroscopy (¹H-MRS), and molecular imaging (PET and SPECT) has enabled researchers to investigate precise alterations in prefrontal–striatal–thalamic circuits, large-scale brain networks, and neurochemical imbalances.

Findings suggest that disruptions in the interaction among the default mode network (DMN), the salience network (SN), and the frontoparietal network (FPN) may play a fundamental role in the emergence and persistence of obsessive symptoms. Moreover, evidence from proton magnetic resonance spectroscopy has revealed abnormalities in glutamate and GABA levels within prefrontal–cingulate and supplementary motor regions, which are associated with symptom severity and compulsive dimensions. In addition, structural connectivity analyses based on DTI demonstrate that microstructural changes in the anterior limb of the internal capsule and thalamo–cortical pathways are directly linked to deficits in cognitive control and decision-making.

The application of these multimodal approaches has not only contributed to a better understanding of the underlying neural mechanisms but has also provided the opportunity to identify reliable biomarkers for predicting responses to pharmacological, cognitive–behavioral, and neuromodulatory interventions. The aim of this article is to provide a systematic and analytical review of studies conducted in the last five years on neuroimaging in OCD and to propose a framework for defining and validating clinically applicable biomarkers. Furthermore, in addition to reviewing findings from clinical and imaging research, the strengths and limitations of these methods will be critically analyzed, and recommendations for future research directions will be presented.