Key result
Specific phobia (N=1,452) was associated with smaller subcortical volumes and larger cortical thickness compared with healthy controls (N=2,991), with all findings driven by adult participants.
Why the study?
Specific phobia is a common anxiety disorder, but the literature on associated brain structure alterations exhibits substantial gaps.
Meta-Analysis (n=4,443)
Yes
Specific phobia is associated with significant structural brain alterations, particularly in adults, with distinct neural underpinnings observed between phobia subtypes.
Answers are grounded in this paper and cite their sources.
Brain structural differences linked to specific phobia and subtypes were confined to adults; leaves open clinical relevance and need for prospective validation.
OBJECTIVE: Specific phobia is a common anxiety disorder, but the literature on associated brain structure alterations exhibits substantial gaps. The ENIGMA Anxiety Working Group examined brain structure differences between individuals with specific phobias and healthy control subjects as well as between the animal and blood-injection-injury (BII) subtypes of specific phobia. Additionally, the authors investigated associations of brain structure with symptom severity and age (youths vs. adults). METHODS: Data sets from 31 original studies were combined to create a final sample with 1,452 participants with phobia and 2,991 healthy participants (62.7% female; ages 5-90). Imaging processing and quality control were performed using established ENIGMA protocols. Subcortical volumes as well as cortical surface area and thickness were examined in a preregistered analysis. RESULTS: Compared with the healthy control group, the phobia group showed mostly smaller subcortical volumes, mixed surface differences, and larger cortical thickness across a substantial number of regions. The phobia subgroups also showed differences, including, as hypothesized, larger medial orbitofrontal cortex thickness in BII phobia (N=182) compared with animal phobia (N=739). All findings were driven by adult participants; no significant results were observed in children and adolescents. CONCLUSIONS: Brain alterations associated with specific phobia exceeded those of other anxiety disorders in comparable analyses in extent and effect size and were not limited to reductions in brain structure. Moreover, phenomenological differences between phobia subgroups were reflected in diverging neural underpinnings, including brain areas related to fear processing and higher cognitive processes. The findings implicate brain structure alterations in specific phobia, although subcortical alterations in particular may also relate to broader internalizing psychopathology.
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Hilbert et al. (2024) conducted a meta-analysis in Specific phobia (n=4,443). Specific phobia vs. Healthy controls was evaluated on Brain structure differences (subcortical volumes, cortical surface area, and cortical thickness). Specific phobia (N=1,452) was associated with smaller subcortical volumes and larger cortical thickness compared with healthy controls (N=2,991), with all findings driven by adult participants.
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