Genetic propensities for verbal and spatial ability have opposite effects on body mass index and risk of schizophrenia

We generated two polygenic scores, one capturing verbal and the other spatial aspects of cognitive ability, using UK Biobank data and studied their effects on various diseases and other traits in the Icelandic population. The score tagging spatial ability associated with higher body mass index (beta = 0.032, p = 3.2 x 10-13), but lower risk of schizophrenia (OR = 0.82, p = 8.8 x 10-9) and other mental disorders. Furthermore, it associated with less openness, a personality trait reflecting curiosity and creativity (beta = -0.023, p = 1.3 x 10-4). Conversely, the score tagging verbal ability associated with lower body mass index (beta = -0.023, p = 1.6 x 10-7) and more openness (beta = 0.045, p = 3.5 x 10-14), but did not associate with risk of schizophrenia (OR = 0.97, p = 0.42). Furthermore, applying genomic structural equation modeling, we observed that the genetic component of verbal ability associated positively with the genetic component of schizophrenia after conditioning on the g factor (bg = 0.193, p = 5.4 x 10-4). Thus, at the genetic level, verbal and spatial ability exhibit contrasting associations with indicators of mental and physical health, as well as with personality.