title: Sex differences in amygdala shape: Insights from Turner syndrome.
abstract: OBJECTIVE
  Sex differences in the manifestation of psychiatric disorders, including anxiety disorders, are among the most prominent findings in psychiatry. The study of Turner syndrome (TS), caused by X-monosomy, has the potential to reveal mechanisms that underline male/female differences in neuropsychiatric disorders. The amygdala has been implicated in numerous neuropsychiatric disorders. Previous studies suggest an effect of TS on amygdala volume as well as on amygdala-related behaviors such as anxiety. Our objective is to investigate the amygdala shape in TS. Specifically, we tested whether amygdala enlargements in TS are localized to specific nuclei implicated in anxiety, such as the basomedial nucleus.
  
  
  METHODS
  We use a surface-based analytical modeling approach to contrast 41 pre-estrogen treatment girls with TS (mean age 8.6 ± 2.4) with 34 age-and sex-matched typically developing (TD) controls (mean age 8.0 ± 2.8). Anxiety symptoms were assessed using the Revised Children's Manifest Anxiety Scale - 2 (RCMAS-2) in both groups.
  
  
  RESULTS
  TS was associated with anomalous enlargement of the amygdala. Surface-based modeling revealed shape differences (increased radial-distances) in bilateral basal and basomedial nuclei within the basolateral complex. RCMAS-2 Total Anxiety t-score was significantly higher in participants with TS compared with TD controls (P = 0.012).
  
  
  CONCLUSIONS
  Group differences in global amygdala volumes were driven by local morphological increases in areas that are critically involved in face emotion processing and anxiety. In the context of increased amygdala volumes in TS, our results also showed increased worry and social anxiety in young girls with TS compared with TD.
authors.affiliation: Center for Interdisciplinary Brain Sciences Research, Stanford University School of Medicine, Stanford, California.|Psychiatry, Sackler Faculty of Medicine, Tel Aviv University, Israel.|Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California.
authors.forename: Tamar
authors.initials: T
authors.lastname: Green
authors.affiliation: Center for Interdisciplinary Brain Sciences Research, Stanford University School of Medicine, Stanford, California.
authors.forename: Kyle C
authors.initials: KC
authors.lastname: Fierro
authors.affiliation: Center for Interdisciplinary Brain Sciences Research, Stanford University School of Medicine, Stanford, California.
authors.forename: Mira M
authors.initials: MM
authors.lastname: Raman
authors.affiliation: Center for Interdisciplinary Brain Sciences Research, Stanford University School of Medicine, Stanford, California.
authors.forename: Lara
authors.initials: L
authors.lastname: Foland-Ross
authors.affiliation: Center for Interdisciplinary Brain Sciences Research, Stanford University School of Medicine, Stanford, California.|Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California.
authors.forename: David S
authors.initials: DS
authors.lastname: Hong
authors.affiliation: Center for Interdisciplinary Brain Sciences Research, Stanford University School of Medicine, Stanford, California.|Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California.|Department of Radiology, Stanford University School of Medicine, Stanford, California.
authors.forename: Allan L
authors.initials: AL
authors.lastname: Reiss
mesh_terms: D000679:Amygdala / Q000000981:diagnostic imaging*; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009929:Organ Size; D012727:Sex Characteristics; D014424:Turner Syndrome / Q000000981:diagnostic imaging*
keywords: Turner syndrome; X-monosomy; amygdala; anxiety; shape analysis and structural MRI
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