Cognitive impairment in the schizophrenia spectrum: exploring the relationships of the g-factor with sociodemography, psychopathology, neurodevelopment, and genetics

Background.Cognitive impairment constitutes a prevailing issue in the schizophrenia spec-trum, severely impacting patients'functional outcomes. A global cognitive score, sensitive tothe stages of the spectrum, would benefit the exploration of potential factors involved in thecognitive decline.Methods.First, we performed principal component analysis on cognitive scores from 768individuals across the schizophrenia spectrum, including first-degree relatives of patients,individuals at ultra-high risk, who had a first-episode psychosis, and chronic schizophreniapatients, alongside 124 healthy controls. The analysis provided 10 g-factors as global cognitivescores, validated through correlations with intelligence quotient and assessed for their sensi-tivity to the stages on the spectrum using analyses of variance. Second, using the g-factors, weexplored potential mechanisms underlying cognitive impairment in the schizophrenia spec-trum using correlations with sociodemographic, clinical, and developmental data, and linearregressions with genotypic data, pooled through meta-analyses.Results.The g-factors were highly correlated with intelligence quotient and with each other,confirming their validity. They presented significant differences between subgroups along theschizophrenia spectrum. They were positively correlated with educational attainment and thepolygenic risk score (PRS) for cognitive performance, and negatively correlated with generalpsychopathology of schizophrenia, neurodevelopmental load, and the PRS for schizophrenia.Conclusions.The g-factors appeared as valid estimators of global cognition, enabling discern-ing cognitive states within the schizophrenia spectrum. Educational attainment and geneticsrelated to cognitive performance may have a positive influence on cognitive functioning, whilegeneral psychopathology of schizophrenia, neurodevelopmental load, and genetic liability toschizophrenia may have an adverse impact.