Background: Recent work in adolescent and adult populations indicates that the comorbidity between a diverse range of psychiatric disorders and symptomologies is largely attributable to the operation of non-specific genetic factors that confer liability for a broad range of psychiatric symptoms, and are themselves inversely correlated with genetic influences on cognitive functioning. Although pairwise associations between specific markers of cognitive development and psychopathology have been reported in very early childhood, psychopathology comorbidity, its etiology, and its relations with general cognitive function in early development have gone unstudied.
Methods: We synthesized individual level data from two American twin studies of early child development: the Texas “Tiny” Twin project (age range = 0 to 5 years, N = 626 twins, measured up to 11 occasions, for a total of 1,398 observations), and the twin subsample from the Early Childhood Longitudinal Study-Birth Cohort (age range = 3 to 7 years; N = ~1,300 twins, measured up to 3 occasions for a total of ~ 2,700 observations), each of which provided parent report measures of internalizing, externalizing, and attentional/self-regulatory problems, and included five measures of cognitive and psychomotor development. We fit confirmatory factor models to test the dimensionality of the 8 phenotypes and, using an integrative data analysis approach, went on to estimate multivariate biometric models of the associations between abilities and psychopathology.
Results: Confirmatory factor models indicated that two factor solutions fit the data well, with the internalizing and externalizing symptoms loading on a general psychopathology (p) factor, the five cognitive/psychomotor measures loading on a general ability (g) factor, and attention/self-regulatory problems loading on both p and g. These general factors were moderately correlated in both samples (rs = -.21 and -.34). Biometric analyses indicated that genetic and environmental influences on p and g were moderately correlated, and that the total correlation between these factors was largely due to overlapping genetic and shared environmental influences.
Conclusions: General psychopathology in early childhood is negatively associated with general cognitive development. The current findings indicate this inverse association is attributable to common genetic and shared environmental factors.
Developmental Disorders (e.g. ADHD) , Psychopathology (e.g., Internalizing, Externalizing, Psychosis) , Cognition: Education, Intelligence, Memory, Attention
