Abnormal Scanning Patterns Based on Eye Movement Entropy in Early Psychosis.

BACKGROUND: Restricted scan path mode is hypothesized to explain abnormal scanning patterns in patients with schizophrenia. Here, we calculated entropy scores (drawing upon gaze data to measure the statistical randomness of eye movements) to quantify how strategical and random participants were to process image stimuli. METHODS: Eighty-six patients with first-episode schizophrenia (FES), 124 individuals at clinical high risk (CHR) for psychosis, and 115 healthy controls (HCs) completed an eye-tracking examination for freely viewing 35 static images (each presented 10s) and cognitive assessments. We compared the group differences in overall entropy score, as well as entropy scores under various conditions. Furthermore, we also investigated the correlation between entropy scores and symptoms along with cognitive function. RESULTS: Increased overall entropy scores were noted in FES and CHR groups relative to HCs, and these differences were already apparent within 0∼2.5s. In addition, the CHR group exhibited higher entropy when viewing low-meaning images compared to HCs. Moreover, the entropy within 0∼2.5s showed significant correlations with negative symptoms in the FES group, Attention/Vigilance scores in the CHR group, as well as Speed of processing and Attention/Vigilance scores across all three groups. CONCLUSIONS: The results indicate that FES and CHR individuals scan pictures more randomly and less strategically than HCs. These patterns also correlate with clinical symptoms and neurocognition. The present study highlights the potential of the eye movement entropy measure as a neurophysiological marker for early psychosis.