title: Increased amygdalar and hippocampal volumes in young adults with social anxiety.
abstract: BACKGROUND
  Functional neuroimaging studies have consistently shown abnormal limbic activation patterns in socially anxious individuals, but structural data on the amygdala and hippocampus of these patients are scarce. This study explored the existence of structural differences in the whole brain, amygdala, and hippocampus of subjects with clinical and subthreshold social anxiety compared to healthy controls. We hypothesized that there would be volumetric differences across groups, without predicting their direction (i.e. enlargement or reduction).
  
  
  METHODS
  Subjects classified as having social anxiety disorder (n = 12), subthreshold social anxiety (n = 12) and healthy controls (n = 14) underwent structural magnetic resonance imaging scans. The amygdala and hippocampus were defined a priori as regions of interest and volumes were calculated by manual tracing. Whole brain volume was calculated using voxel-based morphometry.
  
  
  RESULTS
  The bilateral amygdala and left hippocampus were enlarged in socially anxious individuals relative to controls. The volume of the right hippocampus was enlarged in subthreshold social anxiety participants relative to controls. No differences were found across groups in respect to total brain volume.
  
  
  CONCLUSIONS
  Our results show amygdalar and hippocampal volume alterations in social anxiety, possibly associated with symptom severity. The time course of such alterations and the cellular and molecular bases of limbic plasticity in social anxiety should be further investigated.
authors: Department of Neuroscience and Behavior, Ribeirão Preto Medical School, University of São Paulo (USP), Ribeirão Preto - SP, Brazil.
authors: João Paulo
authors: JP
authors: Machado-de-Sousa
authors: Department of Neuroscience and Behavior, Ribeirão Preto Medical School, University of São Paulo (USP), Ribeirão Preto - SP, Brazil.
authors: Flávia de Lima
authors: Fde L
authors: Osório
authors: Department of Psychiatry, Federal University of São Paulo (UNIFESP), São Paulo - SP, Brazil.
authors: Andrea P
authors: AP
authors: Jackowski
authors: Department of Psychiatry, Federal University of São Paulo (UNIFESP), São Paulo - SP, Brazil.
authors: Rodrigo A
authors: RA
authors: Bressan
authors: Department of Neuroscience and Behavior, Ribeirão Preto Medical School, University of São Paulo (USP), Ribeirão Preto - SP, Brazil.
authors: Marcos H N
authors: MH
authors: Chagas
authors: Department of Psychology, Federal University of Paraíba (UFPB), João Pessoa - PB, Brazil.
authors: Nelson
authors: N
authors: Torro-Alves
authors: Department of Neuroscience and Behavior, Ribeirão Preto Medical School, University of São Paulo (USP), Ribeirão Preto - SP, Brazil.
authors: André L D
authors: AL
authors: Depaula
authors: Department of Neuroscience and Behavior, Ribeirão Preto Medical School, University of São Paulo (USP), Ribeirão Preto - SP, Brazil.
authors: José A S
authors: JA
authors: Crippa
authors: Department of Neuroscience and Behavior, Ribeirão Preto Medical School, University of São Paulo (USP), Ribeirão Preto - SP, Brazil.
authors: Jaime E C
authors: JE
authors: Hallak
mesh_terms: D000328:Adult; D000679:Amygdala / Q000473:pathology*; D001008:Anxiety Disorders / Q000503:physiopathology*; D001931:Brain Mapping; D016022:Case-Control Studies; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D055815:Young Adult