A review of neuroimaging studies of anxiety disorders in China

Background: Anxiety disorders are highly prevalent internationally, and constitute a substantial social and economic burden for patients, their families, and society. A number of neuroimaging studies have investigated the etiology of anxiety disorders in China in the last decade. We discuss the findings of these studies, and compare them with the results of neuroimaging studies of anxiety disorders outside China. Method: A literature search was conducted using the Chinese BioMedical Literature Database, the Chinese Scientific and Technical Periodicals Database, the Chinese Journal Full-text Database, and PubMed, from 1989 to April 2009. We selected neuroimaging studies in which all participants and researchers were Chinese. Results: Twenty-five studies fit our inclusion criteria. Nine studies examined general anxiety disorder (GAD) and/or panic disorder (PD), eight examined obsessive-compulsive disorder (OCD), and eight examined posttraumatic stress disorder (PTSD). Our literature review revealed several general findings. First, reduced regional cerebral blood flow (rCBF) was found in the frontal lobe and temporal lobe in patients with GAD and PD compared with healthy controls. Second, when viewing images with negative and positive valence, relatively increased or decreased activation was found in several brain areas in patients with GAD and PD, respectively. Third, studies with positron emission tomography (PET) and magnetic resonance spectroscopy (MRS) imaging revealed that OCD patients exhibited hyperperfusion and hypoperfusion in some brain regions compared with healthy controls. Neuroimaging studies of PTSD indicate that the hippocampal volume and the N-acetylaspartic acid (NAA) level and the NAA/creatine ratio in the hippocampus are decreased in patients relative to controls. Conclusion: Neuroimaging studies within and outside China have provided evidence of specific neurobiological changes associated with anxiety disorders. However, results have not been entirely consistent across different studies of patients with the same diagnoses. International collaborative research using large samples and robust designs should be conducted in future.