There were significant rs12720071 genotype effects on Processing Speed/Attention and Problem Solving cognitive domain scores (F≥5.56, p≤.03; Figures 3d and 3e). G-allele carriers (who had smaller frontal and temporal WM volumes) had poorer performance on tests assessing Processing Speed/Attention and Problem Solving skills. Genotype-by-marijuana misuse interaction main effects were significant for Problem Solving (F=5.02, p=.04) but not for Processing Speed/Attention (F=1.24, p=.27). Again, rs12720071-G-allele carriers with marijuana abuse/dependence (who had the smallest parietal WM volumes) also had the worst Problem Solving test performance (Mean z=−1.78 versus −1.12, −1.19 and −1.23 in A homozygotes with and without marijuana misuse and G-allele carriers without marijuana misuse respectively; Figure 3e). There was no statistically significant rs12720071 genotype or genotype by-marijuana misuse interaction main effects on Verbal Memory, Language, Visuospatial Abilities and Motor Skills cognitive domain scores (F≤2.41, p≥.12).
