Brain Advance Access published online on December 3, 2007
Brain, doi:10.1093/brain/awm265
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Orbitofrontal volume deficit in schizophrenia and thought disorder
1Clinical Neuroscience Division, Laboratory of Neuroscience, Department of Psychiatry, Veterans Affairs Boston Healthcare System, Brockton Division, Brockton, MA and Harvard Medical School, 2Psychiatry Neuroimaging Laboratory, Department of Psychiatry, Brigham and Women's Hospital, Harvard Medical School and 3Department of Psychology, University of Massachusetts, Boston, MA, USA
Correspondence to:
Dr Robert W. McCarley, Department of Psychiatry (116A), VA Boston Healthcare System, Brockton Division, Harvard Medical School, 940 Belmont St., Brockton, MA 02301, USA. E-mail: robert_mccarley{at}hms.harvard.edu
Orbitofrontal Cortex (OFC) structural abnormality in schizophrenia has not been well characterized, probably due to marked anatomical variability and lack of consistent definitions. We previously reported OFC sulcogyral pattern alteration and its associations with social disturbance in schizophrenia, but OFC volume associations with psychopathology and cognition have not been investigated. We compared chronically treated schizophrenia patients with healthy control (HC) subjects, using a novel, reliable parcellation of OFC subregions and their association with cognition, especially the Iowa Gambling Task (IGT), and with schizophrenic psychopathology including thought disorder. Twenty-four patients with schizophrenia and 25 age-matched HC subjects underwent MRI. OFC Regions of Interest (ROI) were manually delineated according to anatomical boundaries: Gyrus Rectus (GR); Middle Orbital Gyrus (MiOG); and Lateral Orbital Gyrus (LOG). The OFC sulcogyral pattern was also classified. Additionally, MiOG probability maps were created and compared between groups in a voxel-wise manner. Both groups underwent cognitive evaluations using the IGT, Wisconsin Card Sorting Test, and Trail Making Test (TMT). An 11% bilaterally smaller MiOG volume was observed in schizophrenia, compared with HC (F1,47 = 17.4, P = 0.0001). GR and LOG did not differ, although GR showed a rightward asymmetry in both groups (F1,47 = 19.2, P < 0.0001). The smaller MiOG volume was independent of the OFC sulcogyral pattern, which differed in schizophrenia and HC (
2 = 12.49, P = 0.002). A comparison of MiOG probability maps suggested that the anterior heteromodal region was more affected in the schizophrenia group than the posterior paralimbic region. In the schizophrenia group, a smaller left MiOG was strongly associated with worse ‘positive formal thought disorder’ (r = –0.638, P = 0.001), and a smaller right MiOG with a longer duration of the illness (r = –0.618, P = 0.002). While schizophrenics showed poorer performance than HC in the IGT, performance was not correlated with OFC volume. However, within the HC group, the larger the right hemisphere MiOG volume, the better the performance in the IGT (r = 0.541, P = 0.005), and the larger the left hemisphere volume, the faster the switching attention performance for the TMT, Trails B (r = –0.608, P = 0.003). The present study, applying a new anatomical parcellation method, demonstrated a subregion-specific OFC grey matter volume deficit in patients with schizophrenia, which was independent of OFC sulcogyral pattern. This volume deficit was associated with a longer duration of illness and greater formal thought disorder. In HC the finding of a quantitative association between OFC volume and IGT performance constitutes, to our knowledge, the first report of this association.
Key Words: schizophrenia; orbitofrontal region; thought disorder; decision making; Iowa gambling task
Abbreviations: ANOVA, analysis of variance; GR, Gyrus Rectus; ICC, intracranial contents; IGT, Iowa Gambling Task; IQ, intelligence quotient; LOG, Lateral Orbital Gyrus; MiOG, Middle Orbital Gyrus; OFC, orbitofrontal cortex; TMT, Trail Making Test; WAIS-III, Wechsler adult intelligence scale, 3rd edition; WCST, Wisconsin card sorting test.
Received May 15, 2007. Revised September 29, 2007. Accepted October 9, 2007.