Disorganization and cognitive impairment in schizophrenia: new insights from electrophysiological findings

In subjects with schizophrenia (SCZ), the disorganization dimension is a strong predictor of real-life functioning. “Conceptual disorganization” (P2), “Difficulty in abstract thinking” (N5) and “Poor attention” (G11) are core features of the disorganization factor, evaluated using the Positive and Negative Syndrome Scale. The heterogeneity of this dimension and its overlap with neurocognitive deficits are still debated. Within the multicenter study of the Italian Network for Research on Psychoses, we investigated electrophysiological and neurocognitive correlates of disorganization and its component items to assess the heterogeneity of this dimension and its possible overlap with neurocognitive deficits. Resting state EEG was recorded in 145 stabilized SCZ and 69 matched healthy controls (HC). Spectral amplitude was averaged in ten frequency bands. Neurocognitive domains were assessed by MATRICS Consensus Cognitive Battery (MCCB). RAndomization Graphical User software explored band spectral amplitude differences between groups and correlations with disorganization and MCCB scores in SCZ. Correlations between disorganization and MCCB scores were also investigated. Compared to HC, SCZ showed increased delta, theta, and beta 1 and decreased alpha 2 activity. A negative correlation between alpha 1 and disorganization was observed in SCZ. At the item level, only “N5” showed the same correlation. MCCB neurocognitive composite score was associated with disorganization, “P2” and “N5”. Our findings suggest only a partial overlap between disorganization and neurocognitive impairment. The association of alpha 1 with the “N5” item suggests that some aspects of disorganization could be underpinned by the impairment of basic neurobiological functions that are only partially evaluated using MCCB.