title: Meta-analysis of functional brain imaging in specific phobia.
abstract: Although specific phobia is a prevalent anxiety disorder, evidence regarding its underlying functional neuroanatomy is inconsistent. A meta-analysis was undertaken to identify brain regions that were consistently responsive to phobic stimuli, and to characterize changes in brain activation following cognitive behavioral therapy (CBT). We searched the PubMed, SCOPUS and PsycINFO databases to identify positron emission tomography and functional magnetic resonance imaging studies comparing brain activation in specific phobia patients and healthy controls. Two raters independently extracted study data from all the eligible studies, and pooled coordinates from these studies using activation likelihood estimation, a quantitative meta-analytic technique. Resulting statistical parametric maps were compared between patients and healthy controls, in response to phobic versus fear-evoking stimuli, and before and after therapy. Thirteen studies were included, comprising 327 participants. Regions that were consistently activated in response to phobic stimuli included the left insula, amygdala, and globus pallidus. Compared to healthy controls, phobic subjects had increased activation in response to phobic stimuli in the left amygdala/globus pallidus, left insula, right thalamus (pulvinar), and cerebellum. Following exposure-based therapy widespread deactivation was observed in the right frontal cortex, limbic cortex, basal ganglia and cerebellum, with increased activation detected in the thalamus. Exposure to phobia-specific stimuli elicits brain activation that is consistent with current understandings of the neuroanatomy of fear conditioning and extinction. There is evidence that the effects of CBT in specific phobia may be mediated through the same underlying neurocircuitry.
authors.affiliation: Department of Psychiatry and Mental Health, University of Cape Town, Cape Town, South Africa. jonathanipser@gmail.com
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Ipser
authors.forename: Leesha
authors.initials: L
authors.lastname: Singh
authors.forename: Dan J
authors.initials: DJ
authors.lastname: Stein
mesh_terms: D000328:Adult; D000679:Amygdala / Q000473:pathology; D001921:Brain / Q000473:pathology*; D002540:Cerebral Cortex / Q000473:pathology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008032:Limbic System / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D017072:Neostriatum / Q000473:pathology; D010698:Phobic Disorders / Q000473:pathology* / Q000523:psychology*; D013238:Stereotaxic Techniques; D055815:Young Adult
keywords: amygdala; cognitive behavioral therapy; magnetic resonance imaging; meta-analysis; phobic disorders