DNA fragmentation decreased in schizophrenia but not bipolar disorder

Background: Apoptosis is thought to play a role in neuronal pathology in schizophrenia and bipolar disorder. Methods: To test this hypothesis, the Klenow method for in situ end-labeling of single-stranded DNA breaks was applied to anterior cingulate cortex from 18 healthy controls, 18 schizophrenic subjects, and 10 bipolar subjects. Results: An unexpected reduction (71%) in Klenow-positive nuclei was found in schizophrenic but not in bipolar Cortexes. Conclusions: To our knowledge to date, this is the first demonstration that there is much less DNA fragmentation in individuals with schizophrenia than in healthy controls and bipolar subjects, which raises a key question as to whether this alteration represents an adaptive or nonadaptive change in the regulation of intracellular signaling and mitochondrial oxidative pathways associated with apoptosis.