Reduced oligodendroglial density in the inferior parietal lobule and lack of insight in schizophrenia

Background and Objectives: Alterations and deficits of oligodendrocytes reported in the grey and white matter in schizophrenia may contribute to neuronal disconnectivity. Prefrontal-parietal functional disconnections have been implicated in diverse clinical symptoms of schizophrenia, including poor insight. We studied the effects of schizophrenia diagnosis and insight on numerical density (Nv) of oligodendrocytes in the inferior parietal lobule (IPL). Methods: Nissl-stained sections from the Stanley "Parietal Collection" from male schizophrenia subjects (n = 24) having poor, fair, or good insight and healthy matched controls (n = 24) were examined. The Nv of oligodendrocytes was estimated in layer 3 of BA 39 and BA 40 of the IPL and in white matter underlying layer 6 by optical dissector method. Results: In BA 39 we found a significant 15% decrease in the Nv of oligodendrocytes in layer 3 in the schizophrenia group. Nv of oligodendrocytes in the poor+fair insight subgroup was 20% lower compared to controls (p< 0.05) and to good insight subgroup (p = 0.055). Nv of oligodendrocytes in the good insight subgroup did not differ from the control group. A significant lateralization of oligodendrocyte density was detected in layer 3 (L>R) only in the control group. There were no significant group differences in the Nv of oligodendrocytes in BA 40 or in the white matter underlying BA 39/40 areas. Conclusions: Lack of insight in schizophrenia may be associated with a deficit of oligodendroglia in the grey matter of IPL.