title: Amygdalae morphometry in late-life depression.
abstract: OBJECTIVE
  The amygdalae have been a focus of mood disorder research due to their key role in processing emotional information. It has been long known that depressed individuals demonstrate impaired functional performance while engaged in emotional tasks. The structural basis for these functional differences has been investigated via volumetric analysis with mixed findings. In this study, we examined the morphometric basis for these functional changes in late-life depression (LLD) by analyzing both the size and shape of the amygdalae with the hypothesis that shape differences may be apparent even when overall volume differences are inconsistent.
  
  
  METHODS
  Magnetic resonance imaging data were acquired from 11 healthy, elderly individuals and 14 depressed, elderly individuals. Amygdalar size was quantified by computing total volume and amygdalar shape was quantified with a shape analysis method that we have developed.
  
  
  RESULTS
  No significant volumetric differences were found for either amygdala. Nevertheless, localized regions of significant shape variation were detected for the left and right amygdalae. The most significant difference was contraction (LLD subjects as compared to control subjects) in a region typically associated with the basolateral nucleus, which plays a key role in emotion recognition in neurobiologic models of depression.
  
  
  CONCLUSIONS
  In this LLD study, we have shown that, despite insignificant amygdalar volumetric findings, variations of amygdalar shape can be detected and localized. With further investigation, morphometric analysis of various brain structures may help elucidate the neurobiology associated with LLD and other mood disorders.
authors.affiliation: Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA. rjtst21@pitt.edu
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Tamburo
authors.forename: Greg J
authors.initials: GJ
authors.lastname: Siegle
authors.forename: George D
authors.initials: GD
authors.lastname: Stetten
authors.forename: C Aaron
authors.initials: CA
authors.lastname: Cois
authors.forename: Meryl A
authors.initials: MA
authors.lastname: Butters
authors.forename: Charles F
authors.initials: CF
authors.lastname: Reynolds
authors.forename: Howard J
authors.initials: HJ
authors.lastname: Aizenstein
mesh_terms: D000368:Aged; D000679:Amygdala / Q000473:pathology*; D001931:Brain Mapping; D003866:Depressive Disorder / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged