Abstract
In adults, psychiatric disorders are highly comorbid, and are negatively associated with cognitive abilities. Individual cognitive measures have been linked with domains of child psychopathology, but the specificity of these associations and the extent to which they reflect shared genetic influences are unknown. This study examines the relation between general factors of cognitive ability (g) and psychopathology (p) in early development using two genetically-informative samples: the Texas "Tiny" Twin project (TXtT; N = 626 individuals, age range = 0.16 - 6.31 years) and the Early Childhood Longitudinal Study-Birth Cohort (ECLS-B; N ≈ 1,300 individual twins, age range = 3.7 - 7.1 years). The total p-g correlation (-.21 in ECLS-B; -.34 in TXtT) was primarily attributable to genetic and shared environmental factors. The early age range of participants indicates that the p-g association is a reflection of overlapping genetic and shared environmental factors that operate in the first years of life.