Figure 4. Association between genetic variants for general cognitive function and global brain imaging markers. Association between genetic variants for general cognitive function and both volumetric and global white matter microstructural integrity markers. For the volumetric outcomes, analyses were adjusted for age and sex, and additionally for intracranial volume if the outcome was not intracranial volume. For the microstructural integrity outcomes, analyses were adjusted for age, sex, white matter and white matter lesion volume. Three polygenic scores are presented: a cognition polygenic score including all independent lead variants (N=170); a cognition polygenic score only including variants with a p>0.05 for the association with the developmental component of cognition, i.e. educational attainment and intracranial volume (N=36); and an educational attainment polygenic score, which contains the lead genetic variants for cognitive performance (N=170) but uses the weights for educational attainment. Also, the five top genetic variants for the association with these brain imaging markers are presented. Positive associations depicted in blue correspond to a larger volume or a better white matter microstructural integrity. Larger blocks indicate higher t-values. Significance levels are indicated by asterisks: *p<0.05, nominally significant; **p<0.0101, adjusted for the number of independent traits as calculated through 10,000 permutations. No association was significant after additional adjustments for the number of genetic variants tested (p<5.9x10-5; 0.0101/170).