Interstitial cells of the white matter in the inferior parietal cortex in schizophrenia: An unbiased cell-counting study

Previous studies have found an increased density of the interstitial cells of the white matter (ICWMs) in the frontal and temporal cortex in schizophr enia. Some data suggested this abnormality was restricted to a subgroup of patients, whose clinical features were consistent with the presence of the deficit syndrome. Clinical studies suggest deficit features are due to an a bnormality in a cortical-subcortical circuit that includes dorsolateral pre frontal and inferior parietal cortex. We compared the density of ICWMs labe led for MAP2 immunoreactivity in Brodmann area 39 (inferior parietal cortex ) from nine schizophrenia subjects (three deficit and six nondeficit) and n ine matched controls using an unbiased cell-counting technique. The density of ICWMs was significantly greater in the deficit syndrome subjects compar ed to the nondeficit schizophrenia group (respective means +/- SEM, 0.22 +/ - 0.04, and 0.13 +/- 0.02; P < 0.05). The density of ICWMs in the deficit g roup was also significantly greater (P < 0.05) than that of the control gro up (0.09 +/- 0.02), but the nondeficit and control groups were not signific antly different. These findings 1) confirm that an abnormal placement of ne urons in the white matter is found in schizophrenia, 2) provide evidence fo r a microscopic anatomical abnormality in the inferior parietal cortex, and 3) suggest the ICWM abnormality may be confined to deficit patients. (C) 1 999 Wiley-Liss, Inc.