As detailed in Table 3, three DRD1 SNP × digit span backward interactions were detected at p < .05 that on average accounted for 10% of the variance in attention problem change from baseline to follow-up after controlling for all other variables in the respective model. Two of these interactions (SNPs rs4532 and rs265978) remained significant after Bonferroni correction and accounted for 11% of the variance in ADHD symptom change during development. As depicted in Figure 2, plotting the simple slopes revealed a strong link between improvements in digit span backward (i.e. working memory manipulation) and the remission of ADHD symptoms during the course of development in individuals who were homozygous for the major alleles of SNPs rs4532 and rs265978. By contrast, this link was not found in carriers of the minor allele of these two DRD1 SNPs. In other words, change in the ability to manipulate verbal information in working memory was unrelated to the magnitude of change in ADHD symptoms in minor allele carriers. Non-model-based plots of raw CBCL-AP and digit span backward change scores for each individual
