title: Reduced cortical gamma-aminobutyric acid levels in depressed patients determined by proton magnetic resonance spectroscopy.
abstract: BACKGROUND
  Several lines of emerging evidence suggest that dysfunction of gamma-aminobutyric acid (GABA) systems is associated with major depression. However, investigation of this hypothesis is limited by difficulty obtaining noninvasive in vivo measures of brain GABA levels. In this study we used in vivo proton magnetic resonance spectroscopy to investigate the hypothesis that abnormalities in the GABA neurotransmitter system are associated with the neurobiologic processes of depression.
  
  
  METHODS
  The GABA levels were measured in the occipital cortex of medication-free depressed patients meeting DSM-IV criteria (n = 14) and healthy control subjects with no history of mental illness (n = 18) using a localized difference editing proton magnetic resonance spectroscopy protocol. An analysis of covariance was employed to examine the effects of depression, sex, and age.
  
  
  RESULTS
  The depressed patients demonstrated a highly significant (52%) reduction in occipital cortex GABA levels compared with the group of healthy subjects. While there were significant age and sex effects, there was no interaction of diagnosis with either age or sex.
  
  
  CONCLUSIONS
  This study provides the first evidence of abnormally low cortical GABA concentrations in the brains of depressed patients.
authors.affiliation: Department of Psychiatry, Yale University School of Medicine, New Haven, Conn, USA. gerard.sanacora@yale.edu
authors.forename: G
authors.initials: G
authors.lastname: Sanacora
authors.forename: G F
authors.initials: GF
authors.lastname: Mason
authors.forename: D L
authors.initials: DL
authors.lastname: Rothman
authors.forename: K L
authors.initials: KL
authors.lastname: Behar
authors.forename: F
authors.initials: F
authors.lastname: Hyder
authors.forename: O A
authors.initials: OA
authors.lastname: Petroff
authors.forename: R M
authors.initials: RM
authors.lastname: Berman
authors.forename: D S
authors.initials: DS
authors.lastname: Charney
authors.forename: J H
authors.initials: JH
authors.lastname: Krystal
mesh_terms: D000328:Adult; D000367:Age Factors; D002540:Cerebral Cortex / Q000737:chemistry*; D003866:Depressive Disorder / Q000175:diagnosis* / Q000378:metabolism; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009778:Occipital Lobe / Q000737:chemistry*; D012737:Sex Factors; D005680:gamma-Aminobutyric Acid / Q000032:analysis*
chemical_list: D005680:gamma-Aminobutyric Acid