Evaluation of superior vermal Purkinje cell placement in mental illness

Background: A number of neuroimaging and neuropathological studies have rep orted abnormalities in the cerebellar vermis in schizophrenia and bipolar d isorder In an effort to further understand vermal abnormalities in mental i llness, we have analyzed ectopic placement of Purkinje-like cells. Methods: The superior cerebellar vermis was evaluated in 39 cases of severe mental illness [schizophrenia (n = 12), bipolar disease (n = 12), and depr ession (n = IS)]. We also examined 9 subjects with polysubstance abuse and IS normal controls. All normally placed Purkinje cells and displaced Purkin je-like cells (i.e., in the internal granule layer and intrafoliar white ma tter) were counted in the same foliar field. The ratio of displaced Purkinj e-like cells to total Purkinje cells and Purkinje cell density were calcula ted. Results: No significant difference in the ratio of displaced to normally pl aced Purkinje cells or in Purkinje cell density between groups of subjects was found. Conclusions: Our study does not support a hypothesis of abnormalities of Pu rkinje cell migration or other events related to their displacement as a ba sis for the vermal abnormalities reported previously in schizophrenia and b ipolar disorder. Biol Psychiatry 1999;45:1370-1375 (C) 1999 Society of Biol ogical Psychiatry.