Strong genetic overlap between executive functions and intelligence.

Abstract

Executive functions (EFs) are cognitive processes that control, monitor, and coordinate more basic cognitive processes. EFs play instrumental roles in models of complex reasoning, learning, and decision-making, and individual differences in EFs have been consistently linked with individual differences in intelligence. By middle childhood, genetic factors account for a moderate proportion of the variance in intelligence, and these effects increase in magnitude through adolescence. Genetic influences on EFs are very high, even in middle childhood, but the extent to which these genetic influences overlap with those on intelligence is unclear. We examined genetic and environmental overlap between EFs and intelligence in a racially and socioeconomically diverse sample of 811 twins ages 7-15 years (M = 10.91, SD = 1.74) from the Texas Twin Project. A general EF factor representing variance common to inhibition, switching, working memory, and updating domains accounted for substantial proportions of variance in intelligence, primarily via a genetic pathway. General EF continued to have a strong, genetically-mediated association with intelligence even after controlling for processing speed. Residual variation in general intelligence was influenced only by shared and nonshared environmental factors, and there remained no genetic variance in general intelligence that was unique of EF. Genetic variance independent of EF did remain, however, in a more specific perceptual reasoning ability. These results provide evidence that genetic influences on general intelligence are highly overlapping with those on EF.

Modeling the Covariance Structure of Complex Datasets Using Cognitive Models: An Application to Individual Differences and the Heritability of Cognitive Ability

“…Our results fall in line with the previous findings of Engelhardt et al. (), who used psychometric testing to show that a strong genetic component exists within executive functions.…”

“…While previous studies made the simple assumption that observed heritability in response time is attributable solely to heritability in the speed of mental processing (Beaujean, 2005;Finkel & Pedersen, 2004;Kochunov et al, 2016;Luciano et al, 2001;Ogata et al, 2014;Posthuma et al, 2002;Vernon, 1989), we found greater genetic contribution to response caution than to underlying cognitive speed within the memory task assessed. Our results fall in line with the previous findings of Engelhardt et al (2016), who used psychometric testing to show that a strong genetic component exists within executive functions. Previous twin-based studies have investigated the heritability of decision-related processes, such as processing speed, through psychometric tests, linear correlations, and structural equation models (Vernon, 1989).…”

“…Previous cognitive heritability research has also suggested a strong genetic component of response caution, with Engelhardt et al. () suggesting that the entire heritable component seen in general intelligence might be explained through the heritability in executive functions.…”

“…For example, the observed response time with which people complete a standard memory task is undoubtedly influenced by how efficiently they can retrieve memories, but it is also influenced by how quickly they execute motor responses, and by how cautiously they respond. Previous cognitive heritability research has also suggested a strong genetic component of response caution, with Engelhardt et al (2016) suggesting that the entire heritable component seen in general intelligence might be explained through the heritability in executive functions.…”

Evidence for a unitary structure of spatial cognition beyond general intelligence

“…A hierarchical structure, which highlights both communalities 384 and differences between cognitive tests, has also been found to provide the most accurate characterization in 385 other domains of cognition, most notably executive functions. [39][40][41][42] Also consistent with what has been observed 386 for individual differences in executive functions, we found that genetic factors were largely shared across all 387 tests of spatial abilities. These results point to the existence of a common genetic network at the basis of 388 individual differences in spatial ability, therefore providing additional support for a unitary account of spatial 389 cognition.…”