Abnormal default-mode network homogeneity in first-episode, drug-naive schizophrenia at rest

Abstract

Background: Dysconnectivity hypothesis posits that schizophrenia relates to abnormal resting-state connectivity within the default-mode network (DMN) and this aberrant connectivity is considered as contribution of difficulties in self-referential and introspective processing. However, little is known about the alterations of the network homogeneity (NH) of the DMN in schizophrenia. In the present study, we used an automatic NH method to investigate the NH of the DMN in schizophrenia patients at rest.

Methods: Forty-nine first-episode, drug-naive schizophrenia patients and 50 age-, gender-, and education-matched healthy controls underwent a resting-state functional magnetic resonance imaging (fMRI). An automated NH approach was used to analyze the data.

Results: Patients exhibited lower NH than controls in the left medial prefrontal cortex (MPFC) and the right middle temporal gyrus (MTG). Significantly higher NH values in the left posterior cingulate cortex (PCC) and the right cerebellum Crus I were found in the patient group than in the control group. No significant correlation was found between abnormal NH values and Positive and Negative Symptom Scale (PANSS) scores, duration of untreated psychosis (DUP), age or years of education in the patient group.

Conclusions: Our findings suggest that abnormal NH of the DMN exists in first-episode, drug-naive schizophrenia and further highlight the importance of the DMN in the pathophysiology of schizophrenia.

Keywords: ACC; ADHD; DMN; DPARSF; DUP; Data Processing Assistant for Resting-State fMRI; Default mode network; FC; FMRI; FOV; GRF; Gaussian Random Field; IC; ICA; Independent component analysis; MPFC; MTG; NH; Network homogeneity; PANSS; PCC/Pcu; Positive and Negative Symptom Scale; ROI; Resting state; SCID; STG; Schizophrenia; Structured Clinical Interview of the DSM-IV; TR/TE; anterior cingulate cortex; attention-deficit/hyperactivity disorder; default mode network; duration of untreated psychosis; field of view; functional connectivity; functional magnetic resonance imaging; independent component; independent component analysis; medial prefrontal cortex; middle temporal gyrus; network homogeneity; posterior cingulate cortex/precuneus; region of interest; repetition time/echo time; superior temporal gyrus.