No deficit in total number of neurons in the prefrontal cortex in schizophrenics

The prefrontal cortex (PFC), defined as the cortical region which has the m ajor reciprocal connections with the mediodorsal thalamic nucleus (MD), has often been implicated in schizophrenia. Morphometric studies have shown al tered neuronal density and structure in parts of the PFC in schizophrenic b rains. In addition, the MD and nucleus accumbens have shown a significant d eficit in total neuron number. The purpose of the present study was to esti mate the total neuron number in the PFC in schizophrenics and controls. Usi ng a stereological design, the PFC was studied in eight brains from schizop hrenic patients and 10 age-matched control brains. The bilateral average to tal number of neurons in the PFC was estimated to be 2.76 x 10(9) (CV = S.D ./mean = 0. 15) in the schizophrenic brains whereas that of controls was a non-significantly different value of 3.11 x 10(9) (CV = 0.22; P = 0.23). Fu rthermore, no significant differences were found between the two groups in neuronal density (P = 0.10) or volume of the PFC (P = 0.49). It is of cours e possible that a neuronal deficit, which cannot be revealed when estimatin g the total global number of neurons in the whole PFC, might exist in a sub region of the PFC. In conclusion, uniform loss of neuronal soma in the PFC does not appear to constitute the neural substrate of the pathological proc ess in schizophrenia. (C) 2001 Elsevier Science Ltd. All rights reserved.