The density of pyramidal and nonpyramidal neurons in anterior cingulate cortex of schizophrenic and bipolar subjects

Background: A recent study reported a decreased density of nonpyramidal neu rons (NPs) in layer II of the anterior cingulate (ACCx) and prefrontal (PFC x) cortices of schizophrenic brain that was most pronounced in schizoaffect ive subjects. Our study assessed whether a decrease of NPs in ACCx may show a stronger covariation with affective disorder. A cohort consisting of 12 normal control (CONs), 11 schizophrenic, and 10 bipolar subjects matched fo r age and postmortem interval (PMI) has been analyzed. Methods: A two-dimensional technique was employed for counting cells in a l arge x,y sampling column that extended across layers I through VI of ACCx. Results: There was a 27% reduction in the density of NPs in layer II of the bipolar group, whereas in the schizophrenic group, this density was 16.2% lower. There were no differences in NPs in layers III through VI of either the schizophrenic or bipolar group. Both groups also showed modest decrease s of PNs in the deeper laminae; however, these differences were only signif icant in layer IV of the schizophrenic subjects. The density of glial cells was similar across the control, schizophrenic, and bipolar groups. An Aber crombie correction for cell size did not alter the nature of the results. S ubjects both with and without neuroleptic exposure showed a lower density o f NPs in layer II of bipolar subjects or PNS in deeper laminae of schizophr enic subjects. Conclusions: Overall, the findings reported here suggest that local circuit cells in layer II of ACCx may be decreased in bipolar disorder, whereas pr ojection neurons in deeper laminae are decreased in schizophrenia. Biol Psy chiatry 2001;50:395-406 (C) 2001 Society of Biological Psychiatry.