# EEG microstates as biomarker for psychosis in ultra-high-risk patients

## TL;DR

This study explores how brief patterns in brain activity, called EEG microstates, can help identify individuals at risk of developing psychosis.

## Contribution

The study identifies specific EEG microstate changes that may serve as biomarkers for psychosis and future transition in ultra-high-risk patients.

## Key findings

- Microstate A was increased in patients compared to healthy controls, indicating a general psychopathology marker.
- Microstate B decreased in first-episode psychosis patients compared to ultra-high-risk groups, suggesting a marker for illness progression.
- Microstate D was reduced in ultra-high-risk patients who later transitioned to psychosis, indicating a potential early warning sign.

## Abstract

Resting-state EEG microstates are brief (50–100 ms) periods, in which the spatial configuration of scalp global field power remains quasi-stable before rapidly shifting to another configuration. Changes in microstate parameters have been described in patients with psychotic disorders. These changes have also been observed in individuals with a clinical or genetic high risk, suggesting potential usefulness of EEG microstates as a biomarker for psychotic disorders. The present study aimed to investigate the potential of EEG microstates as biomarkers for psychotic disorders and future transition to psychosis in patients at ultra-high-risk (UHR). We used 19-channel clinical EEG recordings and orthogonal contrasts to compare temporal parameters of four normative microstate classes (A–D) between patients with first-episode psychosis (FEP; n = 29), UHR patients with (UHR-T; n = 20) and without (UHR-NT; n = 34) later transition to psychosis, and healthy controls (HC; n = 25). Microstate A was increased in patients (FEP & UHR-T & UHR-NT) compared to HC, suggesting an unspecific state biomarker of general psychopathology. Microstate B displayed a decrease in FEP compared to both UHR patient groups, and thus may represent a state biomarker specific to psychotic illness progression. Microstate D was significantly decreased in UHR-T compared to UHR-NT, suggesting its potential as a selective biomarker of future transition in UHR patients.