title: Hippocampal and amygdalar volumes in psychotic and nonpsychotic unipolar depression.
abstract: OBJECTIVE
  The limbic system is thought to underlie dysfunctional affective and cognitive processes in individuals with depression. Neuroanatomical studies of subjects with depression have often examined hippocampal and amygdalar structures, since they are two key structures of the limbic system. Research has often but not always found reduced hippocampal volume in patients with major depression. The purpose of the present study was to examine differences in hippocampal and amygdalar volumes in patients with depression subtypes relative to healthy comparison subjects.
  
  
  METHODS
  Participants were 1) patients with major depression with psychosis, 2) patients with major depression without psychosis, and 3) healthy comparison subjects. To examine hippocampal and amygdalar volumes, all participants underwent structural magnetic resonance imaging (MRI). The authors further examined the effects of clinical and chronicity data on these two brain structures.
  
  
  RESULTS
  After age, gender, and total brain volume were controlled, depressed patients with psychosis had a significantly smaller mean amygdala volume relative to depressed patients without psychosis and healthy comparison subjects. There were no differences between depressed patients without psychosis and healthy comparison subjects. Correlational analyses suggested that age of depression onset was strongly associated with amygdala volume. No group differences in hippocampal volume were found.
  
  
  CONCLUSIONS
  There were no differences between depressed patients and healthy comparison subjects in hippocampal volume. However, psychotic but not nonpsychotic depression was associated with reduced amygdala volume. Reduced amygdala volume was not associated with severity of depression or severity of psychosis but was associated with age at onset of depression. Smaller amygdala volume may be a risk factor for later development of psychotic depression. In addition, chronicity of depression and depression subtype might be two important factors associated with hippocampal and amygdalar volumes in depression.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 401 Quarry Rd., Stanford, CA 94305-5723, USA. jkeller@stanford.edu
authors.forename: Jennifer
authors.initials: J
authors.lastname: Keller
authors.forename: Lin
authors.initials: L
authors.lastname: Shen
authors.forename: Rowena G
authors.initials: RG
authors.lastname: Gomez
authors.forename: Amy
authors.initials: A
authors.lastname: Garrett
authors.forename: H Brent
authors.initials: HB
authors.lastname: Solvason
authors.forename: Allan
authors.initials: A
authors.lastname: Reiss
authors.forename: Alan F
authors.initials: AF
authors.lastname: Schatzberg
mesh_terms: D000328:Adult; D000679:Amygdala / Q000033:anatomy & histology*; D000928:Antidepressive Agents / Q000627:therapeutic use; D010054:Brief Psychiatric Rating Scale; D003865:Major Depressive Disorder / Q000175:diagnosis* / Q000188:drug therapy / Q000523:psychology; D005260:Female; D006624:Hippocampus / Q000033:anatomy & histology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011618:Psychotic Disorders / Q000175:diagnosis*; D012720:Severity of Illness Index
chemical_list: D000928:Antidepressive Agents