title: Orbitofrontal cortex gray matter volumes in bipolar disorder patients: a region-of-interest MRI study.
abstract: OBJECTIVE
  Functional and postmortem studies suggest that the orbitofrontal cortex (OFC) is involved in the pathophysiology of bipolar disorder (BD). This anatomical magnetic resonance imaging (MRI) study examined whether BD patients have smaller OFC gray matter volumes compared to healthy comparison subjects (HC).
  
  
  METHODS
  Twenty-eight BD patients were compared to 28 age- and gender-matched HC. Subjects underwent a 1.5T MRI with 3D spoiled gradient recalled acquisition. Total OFC and medial and lateral subdivisions were manually traced by a blinded examiner. Images were segmented and gray matter volumes were calculated using an automated method.
  
  
  RESULTS
  Analysis of covariance, with intracranial volume as covariate, showed that BD patients and HC did not differ in gray matter volumes of total OFC or its subdivisions. However, total OFC gray matter volume was significantly smaller in depressed patients (n = 10) compared to euthymic patients (n = 18). Moreover, total OFC gray matter volumes were inversely correlated with depressive symptom intensity, as assessed by the Hamilton Depression Rating Scale. OFC gray matter volumes were not related to lithium treatment, age at disease onset, number of episodes, or family history of mood disorders.
  
  
  CONCLUSIONS
  Our results suggest that abnormal OFC gray matter volumes are not a pervasive characteristic of BD, but may be associated with specific clinical features of the disorder.
authors.affiliation: Department of Psychiatry, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA. fabiano_nery@hotmail.com
authors.forename: Fabiano G
authors.initials: FG
authors.lastname: Nery
authors.forename: Hua-Hsuan
authors.initials: HH
authors.lastname: Chen
authors.forename: John P
authors.initials: JP
authors.lastname: Hatch
authors.forename: Mark A
authors.initials: MA
authors.lastname: Nicoletti
authors.forename: Paolo
authors.initials: P
authors.lastname: Brambilla
authors.forename: Roberto B
authors.initials: RB
authors.lastname: Sassi
authors.forename: Alan G
authors.initials: AG
authors.lastname: Mallinger
authors.forename: Matcheri S
authors.initials: MS
authors.lastname: Keshavan
authors.forename: Jair C
authors.initials: JC
authors.lastname: Soares
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001714:Bipolar Disorder / Q000473:pathology*; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D017397:Prefrontal Cortex / Q000473:pathology*