Temporal imprecision of the self in drug-free psychosis: Abnormal infraslow phase dynamics and brain complexity

Abstract Self-disturbance is a core feature of schizophrenia (SCZ) and may emerge during the prodromal phase. Temporal imprecision has recently been proposed as a core neural mechanism in schizophrenia, primarily demonstrated in faster EEG frequency ranges. Whether such imprecision extends to infraslow brain dynamics in functional magnetic resonance imaging (fMRI) and relates to self-disturbance in early psychosis remains unknown. Here, we examined resting-state fMRI data from drug-free early psychosis patients (EP drug-free, n = 31, scanned before and after medication) and 31 healthy controls (HC). Brain dynamics were quantified using sample entropy (SampEn) and instantaneous peak frequency (PF) in regions associated with different layers of self-processing (interoceptive, exteroceptive, and mental). Compared to controls, EP drug-free showed higher SampEn and slower mean PF with greater variability than HC, particularly in the regions of the exteroceptive self. Moreover, EP drug-free exhibited a decoupling between SampEn and PF, whereas HC showed strong correlations. Both SampEn and PF significantly contributed to diagnostic classification, and increased SampEn was associated with greater severity of negative, disorganized, and anxiety/depression symptoms. Together, these findings indicate abnormal infraslow brain dynamics in early psychosis, characterized by increased neural complexity and disrupted temporal organization. This temporal imprecision, particularly within the exteroceptive self, may represent a key mechanism linking altered brain dynamics to self-disturbance and psychopathology in early psychosis.