Abstract
BACKGROUND: Cognitive, language, and social abilities are complex, heritable and intertwined traits shaping children's development and later mental health. To better understand cross-trait interrelationships, we model here the structures of shared genomic and shared non-genomic/residual (i.e. broadly environmental) influences, and their correlation ( rGE ), investigating cognitive, language, and social behavioural/communication measures. METHODS: Data were obtained for unrelated children (8-13 years) from two population-based cohorts: the UK Avon Longitudinal Study of Parents and Children (ALSPAC, N≤6,543) and the US Adolescent Brain Cognitive Development(℠) (ABCD) Study (N≤4,412), and analyses were carried out implementing an extended data-driven genetic-relationship-matrix structural equation modelling (GRM-SEM) approach. RESULTS: In ALSPAC, we identified two independent phenotypic domains, each captured by a structurally matching pair consisting of a genomic (A) and a non-genomic/residual (E) factor. The first domain reflected cognitive/language difficulties, with the largest genomic and residual factor loadings ( λA and λE , respectively) for verbal IQ ( λA = 0.73(SE = 0.05) ; λE = 0.57(SE = 0.07) ). The second domain captured social difficulties, with the largest λA and λE for social communication measures ( λA = 0.39(SE = 0.10) ; λE = 0.82(SE = 0.10) ). We identified trait-specific rGE between pairs of A and E factors with different directions of effect (cognition/language rGE = 0.89(SE = 0.18) , social rGE = - 0.62(SE = 0.17) ). rGE patterns were linked to increased measurable A and E contributions for cognition/language difficulties, but decreased contributions for social problems. Analyses in ABCD confirmed the two domains for E and phenotypic structures, although genomic contributions were low. CONCLUSIONS: In childhood, cognitive/language abilities versus social abilities are influenced by distinct genomic and/or environmental factors, potentially interlinked through trait-specific rGE , suggesting differences in developmental processes.