Comparing factor and network models of cognitive abilities using twin data

Network models have become a popular alternative to factor models for analysing the phenotypic relationships among cognitive abilities. Studies have begun to compare these models directly to one another using cognitive ability data, although such a comparison has so far not extended to genetics. Our aim with this study was therefore to compare factor and network models of cognitive abilities first at a phenotypic level and then at a genetic level. We analyzed data from the Twins Early Development Study that were collected using 14 cognitive ability measures from 11,290 twins in the UK aged 12 years old. We conducted phenotypic and genetic analyses in which numerous factor and network models were tested, including a novel network twin model. Factor and network models both provided useful representations of the phenotypic and genetic relationships among cognitive abilities. Surprisingly, several relationships among cognitive abilities within the genetic networks were negative, which suggests that these cognitive abilities might share some genetic variants with inverse effects, although more research is currently needed to confirm this. Implications for future genomic research are discussed.