Brain structure, phenotypic and genetic correlates of reading abilities

Reading is an evolutionary new development that recruits and tunes brain circuitry connecting visual- and language-processing regions. We investigated the structural correlates of reading and whether genetics influence brain-reading associations. First, we identified left hemisphere cortical surface area (CSA) and cortical thickness (CT) correlates of reading in the large ABCD dataset (N=9,013) of 9-to-10-year-olds. Next, the heritability of cognitive and brain measures of interest was examined through complementary approaches. Last, shared genetic effects between reading, reading-related cognitive traits and reading-associated brain measures were examined by computing genetic correlations and polygenic score analyses, and through mediation analyses. Our results support that morphometric brain measures are related to reading abilities, and that the total left CSA in general, and left superior temporal gyrus CSA in particular, contribute to reading partially through genetic factors.