Functional magnetic resonance imaging study of the psychosis risk syndrome using regional homogeneity

Objective To explore whether abnormal brain activities exist in psychosis risk syndrome during resting state by fMRI technique and regional homogeneity(ReHo)approach. Methods fMRI images in resting state were obtained from 17 subjects with psychosis risk syndrome distinguished by Structured Interview for Prodromal Syndromes(SIPS), 16 patients with first-episode schizophrenia according to the DSM-Ⅳ criteria and 18 healthy control subjects, and analyzed using ReHo approach. According to the results of ANOVA, the correlation analysis between the score of Positive and Negative Syndrome Scale(PANSS)and the significant difference brain regions ReHo was conducted. Results Compared with controlsubjects, psychosis risk syndrome group showed increased ReHo in the regions including the left pars orbitalis gyri frontalis inferiois(ReHo value: 0.96 vs.0.77,P=0.000) and the right hippocampus(ReHo value:0.84 vs.0.67, P=0.002);decreased ReHo in the regions including the left medial superior frontal gyrus(ReHo value：1.27 vs.1.44, P=0.034), the right angular gyrus (ReHo value：1.44 vs.1.69,P=0.002)and middle/superior frontal gyrus(ReHo value：1.14 vs.1.39, P=0.002).Patients with first-episode schizophrenia showed increased ReHo in the regions including the right hippocampus(ReHo value：0.88 vs. 0.67,P=0.000),the left putamen(ReHo value：1.02 vs.0.80,P=0.000)and pars triangularis/opercularis gyri frontalis inferiois(ReHo value：1.03 vs.0.85,P=0.000), and decreased ReHo in the regions including the left medial superior frontal gyrus(ReHo value：1.08 vs.1.44,P=0.000),the right precuneus(ReHo value：1.02 vs.1.32, P=0.000), superior temporal gyrus(ReHo value：1.30 vs. 1.63, P=0.000), angular gyrus(ReHo value：1.37 vs. 1.69，P=0.000),middle/superior frontal gyrus(ReHo value：1.05 vs. 1.39, P=0.000) and superior frontal gyrus(ReHo value：0.94 vs. 1.27, P=0.000). Within the psychosis risk syndrome group, the PANSS total score and positive symptom score was negatively correlated with the ReHo in right middle/superior frontal gyrus (r=-0.657, P<0.01; r=-0.535, P<0.05). Within the schizophrenia group, total score of PANSS was negatively correlated with ReHo in the right superior frontal gyrus(r=-0.606, P<0.05), and the negative symptom score was negatively correlated with ReHo in the right superior frontal gyrus and precuneus(r=-0.541, P<0.05; r=-0.524, P<0.05), and the common score was negatively correlated with ReHo in the right superior frontal gyrus and superior temporal gyrus(r=-0.534, P<0.05; r=-0.548, P<0.05). Conclusions Abnormal brain activities during resting state might exist in subjects with psychosis risk syndrome, which could be helpful for exploring the pathological mechanisms of early schizophrenia. Key words: Psychosis risk syndrome; Schizophrenia; Magnetic resonance imaging; Regional homogeneity