Neuroimaging of Serotonin System in Anxiety Disorders

A large body of research including animal and human studies has confirmed the crucial role of the serotonin (5-HT) system in the regulation of anxiety-related behaviour and traits. In the past decade, the functional status of the 5-HT system in anxiety disorders has been regularly investigated by novel neuroimaging techniques, such as single-photon emission computed tomography (SPECT) and positron emission tomography (PET). Although these studies shed more light on several aspects of the 5-HT functioning in patients with anxiety disorders, the current knowledge about the specific role of the 5-HT system in particular anxiety phenotypes remains fragmentary. In this paper, we review the available data from SPECT and PET imaging studies of the 5-HT system in anxiety disorders, attempt to dissect the involvement of the 5-HT in neural circuits of anxiety and discuss some issues that need to be considered for further research in this area.