Reduced number of mediodorsal and anterior thalamic neurons in schizophrenia

Background: The thalamus is a brain region of interest in rite study of sch izophrenia because it provides critical input to brain regions such as the prefrontal, cingulate, and temporal cortices, where abnormalities have been repeatedly observed in patients with schizophrenia. Post-mortem anatomic s tudies have rarely investigated the thalamus in this population. Methods: Postmortem tissue was obtained from the left hemisphere of eight m ale schizophrenic patients and eight male age-matched control subjects, The optical dissector stereologic procedure was used to count neurons in the m ediodorsal (MD) and anteroventral/anteromedial (AV/AM) nuclei of the thalam us. Results: The number of neurons and volume of the MD were significantly redu ced by 35% and 24%, respectively. The MD cell number reduction was a consis tent finding; every control subject had more and every schizophrenic subjec t had fewer than 3.5 million neurons. Neuron number was also significantly reduced (16%) in the AV/AM nuclei. Conclusions: The present data indicate that schizophrenia is associated wit h robust reductions in nerve cell numbers in nuclei that communicate with t he prefrontal cortex and limbic system. These thalamic anatomic deficits ma y be responsible, in part, for previous reports of such prefrontal cortical abnormalities as reduced synaptic density, reduced volume, and metabolic h ypofunction. (C) 2000 Society of Biological Psychiatry.