Functional neuroimaging of anxiety: a meta-analysis of emotional processing in PTSD, social anxiety disorder, and specific phobia.
OBJECTIVE
The study of human anxiety disorders has benefited greatly from functional neuroimaging approaches. Individual studies, however, vary greatly in their findings. The authors searched for common and disorder-specific functional neurobiological deficits in several anxiety disorders. The authors also compared these deficits to the neural systems engaged during anticipatory anxiety in healthy subjects.


METHODS
Functional magnetic resonance imaging and positron emission tomography studies of posttraumatic stress disorder (PTSD), social anxiety disorder, specific phobia, and fear conditioning in healthy individuals were compared by quantitative meta-analysis. Included studies compared negative emotional processing to baseline, neutral, or positive emotion conditions.


RESULTS
Patients with any of the three disorders consistently showed greater activity than matched comparison subjects in the amygdala and insula, structures linked to negative emotional responses. A similar pattern was observed during fear conditioning in healthy subjects. Hyperactivation in the amygdala and insula were, of interest, more frequently observed in social anxiety disorder and specific phobia than in PTSD. By contrast, only patients with PTSD showed hypoactivation in the dorsal and rostral anterior cingulate cortices and the ventromedial prefrontal cortex-structures linked to the experience and regulation of emotion.


CONCLUSIONS
This meta-analysis allowed us to synthesize often disparate findings from individual studies and thereby provide neuroimaging evidence for common brain mechanisms in anxiety disorders and normal fear. Effects unique to PTSD furthermore suggested a mechanism for the emotional dysregulation symptoms in PTSD that extend beyond an exaggerated fear response. Therefore, these findings help refine our understanding of anxiety disorders and their interrelationships.
Etkin
Amit
A
Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 401 Quarry Rd., Stanford, CA 94305, USA. amitetkin@stanford.edu
Wager
Tor D
TD
D000328:Adult; D000679:Amygdala / Q000000981:diagnostic imaging / Q000503:physiopathology; D001008:Anxiety Disorders / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000503:physiopathology; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D003213:Conditioning, Psychological / Q000502:physiology; D004644:Emotions / Q000502:physiology*; D005149:Facial Expression; D005239:Fear / Q000502:physiology; D005260:Female; D006801:Humans; D008016:Life Change Events; D008032:Limbic System / Q000000981:diagnostic imaging / Q000503:physiopathology; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data; D008297:Male; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000503:physiopathology; D010698:Phobic Disorders / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000503:physiopathology; D049268:Positron-Emission Tomography / Q000706:statistics & numerical data; D017397:Prefrontal Cortex / Q000000981:diagnostic imaging / Q000503:physiopathology; D013313:Stress Disorders, Post-Traumatic / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000503:physiopathology; D014796:Visual Perception / Q000502:physiology