Differences of regional homogeneity and cognitive function between psychotic depression and drug-naïve schizophrenia

Background: Psychotic depression (PD) and schizophrenia (SCZ) are disorders with shared symptoms but unique causes, development, and treatments. Identifying them based on symptoms is difficult, requiring deeper comprehension of cognitive and neural mechanisms for accurate diagnosis and treatment. Aim: This study aims to compare cognitive impairments and brain functional activities in PD and SCZ, in order to identify unique features of each disorder. Methods: We studied 42 PD and 30 SCZ patients using RBANS and rs-fMRI. We computed ReHo values from the rs-fMRI data and compared RBANS scores between groups. We also investigated the correlation between cognition and brain function using Pearson analysis. Results: (1) SC group had lower RBANS scores than PD group in all test sections; (2) Left precuneus had significant ReHo difference between PD and SC groups, with SCZ group showing significantly increased ReHo (p < 0.05); (3) Negative correlation found between visuospatial construction score, delayed memory score and ReHo value of left precuneus by Pearson correlation analysis. conclusion: Cognitive impairment is more severe in SCZ than PD. Elevated left precuneus activity distinguishes PD from SCZ and relates to cognitive deficits in both, offering neuroimaging evidence for differential diagnosis and insight into cognitive impairment pathology.