Evidence for orbitofrontal pathology in bipolar disorder and major depression, but not in schizophrenia.
BACKGROUND
The orbitofrontal cortex is involved in the monitoring of reward and in judgement. Lesion studies and functional neuroimaging investigations implicate this region in affective disorders, and altered neuronal and glial cell composition have been observed in this region in subjects with major depressive disorder (MDD).


OBJECTIVE
Stereologically based investigation of caudal orbitofrontal cortex (cOFC), in 60 postmortem brains from four groups of 14 subjects each with bipolar disorder (BPD), schizophrenia and MDD.


METHODS
Glial cell and neuronal size and density were examined in all subjects using stereological probes such as the nucleator and the optical disector.


RESULTS
We found statistical evidence for a neuronal size reduction in BPD in layer 1 (21%, p=0.007) and a trend for a reduction in layer 5 (20%, p=0.05). There was a significant interaction effect of brain hemisphere and group on neuronal size in layer 3 (p=0.001), with evidence for reduced layer 3 neuronal sizes in MDD (30%, p<0.001). We found no evidence for group differences in glial cell size nor for differences in glial or neuronal density.


CONCLUSIONS
These findings provide preliminary evidence that neuronal size reduction in cOFC is a component of the pathology of BPD. Overall, the data implicate this cortical region in affective disorders, but provide no evidence for neuronal or glial pathology in this region in schizophrenia.
Cotter
David
D
Department of Psychiatry, Education and Research Centre, Beaumont Hospital, Royal College of Surgeons in Ireland, Dublin, Ireland. drcotter@rcsi.ie
Hudson
Lance
L
Landau
Sabine
S
D000328:Adult; D001714:Bipolar Disorder / Q000473:pathology*; D002452:Cell Count; D003865:Major Depressive Disorder / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009457:Neuroglia / Q000473:pathology; D017397:Prefrontal Cortex / Q000473:pathology*; D012559:Schizophrenia / Q000503:physiopathology*