Peripheral and neuroimaging biomarkers of anxiety disorders

Anxiety disorders are complex psychiatric conditions characterized by excessive fear, anxiety, and avoidance behaviours. Despite their high prevalence and burden, anxiety disorders remain poorly understood, and diagnosis relies heavily on clinical interviews. Recent advances in peripheral and neuroimaging biomarkers offer promising avenues for improving diagnosis, treatment, and understanding of anxiety disorders. Peripheral biomarkers, such as cortisol, inflammatory cytokines, and neuropeptides, have been shown to be altered in anxiety disorders. For instance, elevated cortisol levels and altered cortisol awakening responses have been observed in individuals with anxiety disorders. Neuroimaging biomarkers, including functional magnetic resonance imaging and diffusion tensor imaging, have revealed altered neural circuitry and connectivity in anxiety disorders. Studies have implicated the amygdala, hippocampus, and prefrontal cortex in the pathophysiology of anxiety disorders. Abnormalities in these regions, including altered volume, activity, and connectivity, have been linked to symptom severity and treatment response. This comprehensive review aims to summarize the current state of knowledge on peripheral and neuroimaging biomarkers in anxiety disorders.