Anterior cingulate cortex pathology in schizophrenia and bipolar disorder

To explore possible morphological abnormalities in the dorsal and subgenual parts of anterior cingulate cortex in mood disorders and schizophrenia, we performed a quantitative postmortem study of 44 schizophrenic patients, 21 patients with sporadic bipolar disorder, 20 patients with sporadic major d epression, and 55 age- and sex-matched control cases. All individuals were drug naive or had received psychotropic medication for less than 6 months, and had no history of substance abuse,. Neuron densities and size were esti mated on cresyl violet-stained sections using a stereological counting appr oach. The distribution and density of microtubule-associated (MAP2, MAP1b) and tau proteins were assessed by immunocytochemistry and quantitative immu nodot assay. Mean total and laminar cortical thicknesses as well as mean py ramidal neuron size were significantly decreased in the dorsal and subgenua l parts of areas 24 (24sg) in schizophrenic cases. Patients with bipolar di sorder showed a substantial decrease in laminar thickness and neuron densit ies in layers III, V, and VI of the subgenual part of area 24, whereas pati ents with major depression were comparable to controls. Immunodot assay sho wed a significant decrease of both MAP2 and MAP1b proteins in bipolar patie nts but not in patients with schizophrenia and major depression. The neuroa natomical and functional significance of these findings are discussed in th e light of current hypotheses regarding the role of areas 24 and 24sg in sc hizophrenia and bipolar disorder.