We also note that almost all variants that influence ADHD overlap with educational attainment51, and that the vast majority (79%) are associated with decreased educational attainment, consistent with the overall negative genetic correlation. For the models indicating a high number of shared variants (ADHD vs. MDD, SCZ, BMI, educational attainment, age at first birth and smoking), we found support (evaluated using the Akaike Information Criterion52) for the best fitting MiXeR models above the “minimal model”, which indicate that the data support the existence of a polygenic overlap, beyond the minimal level needed to explain the observed genetic correlations. For ADHD vs. ASD, the model had limited support, and the results should therefore be interpreted with caution.
