Comparative study on default mode network in schizophrenia and bipolar mania

Abstract

Objective To explore the functional connectivity alterations in patients with schizophrenia and bipolar disorder. Methods Resting-state functional magnetic resonance imaging data were collected from 22 patients who meet the diagnosis criteria of bipolar mania in DSM-IV, 22 patients who meet the diagnosis criteria of schizophrenia in DSM-IV and 22 normal controls. Default mode network was reconstructed using seed-based functional connectivity approach and comparison was done. The association of connectivity strength and clinical measures were also examined. Results (1) Compared to controls, patients with schizophrenia showed increased connectivity strength within the cortical midline structures including the dorsal medial prefrontal lobe and precuneus.(2) Patients with bipolar mania exhibited decreased connectivity strength within the limbic system, including the medial prefrontal cortex, hippocampus, and posterior cingulate cortex.(3) Both patient groups showed increased connectivity strength in precuneus and decreased connectivity strength in lateral temporal lobe.(4) The connectivity strength of dorsal medial prefrontal lobe and precuneus were positively correlated with negative symptoms in patients. Conclusion There are partly overlapped patterns of functional alteration in schizophrenia and bipolar disorder, and these patterns are associated with neuropathology of two diseases. Patients with schizophrenia show increased connectivity strength within the cortical midline structures, while patients with bipolar mania exhibit decreased connectivity strength within the prefrontal and limbic system. Key words: Schizophrenia; Bipolar disorder; Functional connectivity; Default mode network