Profiling electrophysiological and linguistic markers: implications for clinical and functional outcome in schizophrenia

Abstract

Language disruption, especially at the pragmatic level, is a hallmark of schizophrenia, impacting functional outcome. While still poorly explored, electrophysiological (EEG) underpinnings of language in schizophrenia may disclose novel treatment targets, as well as insights on etiopathogenetic mechanisms. Furthermore, combining electrophysiological and linguistic markers could refine clinical stratification of patients within the same diagnostic category to guide customized treatment. In this study, we first explored the interplay between neurophysiological markers – i.e., mismatch Negativity (MMN) and the aperiodic component of the power spectrum (offset and exponent) – and pragmatics. Then we combined these features to identify electrophysiological and linguistic profiles and test their associations with symptom severity and functional impairment. Fifty patients with schizophrenia were assessed for pragmatics, vocabulary, symptoms, functioning and well-being. Their EEG was recorded during a resting state condition, to capture aperiodic activity, and a passive odd-ball task to evoke MMN. Correlation analyses showed significant associations between pragmatics and both MMN and aperiodic offset. A two-step cluster analysis including aperiodic offset, MMN, and pragmatic measures revealed two profiles, with Cluster 2 showing alteration in EEG indexes and pragmatics skills, as well as a more disrupted clinical and functional outcome. Overall, this study not only expands our knowledge of the electrophysiological correlates of pragmatic language impairment in schizophrenia, showing for the first time a meaningful link with MMN and the aperiodic component, but also highlights the utility of combining EEG and linguistic data to distinguish patients’ profiles, paving the way to more personalized treatment strategies, tailored to individual specificities.