Aperiodic activity modulation during visual oddball paradigm in clinical high-risk individuals and relationship with...

Abnormalities in event-related potential P300 have been reported in clinical high-risk (CHR) populations, reflecting deficits in cognitive processes. Studies suggest that task-induced changes in the exponent are associated with working memory capacity. The present study aimed to compare visual P300 amplitude and task-related exponent modulation during a visual oddball paradigm among CHR individuals, and to examine whether the exponent could serve as potential biomarker for clinical outcomes.

CHR and healthy controls (HC) were enrolled and completed a visual oddball task while EEG was recorded. CHR participants were divided into psychosis converters (CHRC) and non-converters (CHR-NC) group according to the clinical outcomes of two-year follow-up. P300 amplitude and the pre- to post-stimulus change in aperiodic exponent (Δ-exponent) were analyzed. Logistic regression modeling was performed to evaluate the predictive power of Δ-exponent.

P300 amplitude at parietal region was significantly lower in the CHR-C group compared to the HC (p = 0.01) group. The Δ-exponent was significantly attenuated in CHR-C relative to HC (p < 0.01) and CHR-NC (p = 0.01). Logistic regression showed that Δ-exponent may have better predictive power than P300 amplitude (mean AUC difference 0.13, 95%CI: 0.002-0.38), and a reduction in Δ-exponent was associated with psychosis conversion (OR = 0.43(0.23-0.75), p < 0.01).

Attenuation of the visual oddball task-induced change in aperiodic exponent is observed in CHR individuals who later convert to psychosis and may hold better predictive power compared to P300 amplitude. Δ-exponent may serve as a potential neurobiological biomarker in the CHR population.