Links between DRD4, executive attention, and alphabetic skills in a nonclinical sample.

Background: The dopamine D4 receptor gene (DRD4) has been linked to attention deficit hyperactivity disorder (ADHD) and reading disorders. In this study, we examined whether diminished anticipatory dopamine cell firing - typical of the long variant of the DRD4 allele - is related to emergent and advanced alphabetic skills, and whether executive attention is a mediator between this allele and alphabetic skills.

Method: We tested alphabetic skills in a normative sample of 159 children in both kindergarten and Grade 1, and executive attention 1 year earlier. Cheek cells were collected and genomic DNA was isolated from the samples using the Chemagic buccal swab kit on a chemagen Module I workstation.

Results: Thirty-seven percent of the children were carriers of at least one DRD4 7-repeat allele. Carriers of the long variant scored lower on alphabetic skills, and executive attention appeared to be a mediator of the relation between characteristics of DRD4 and alphabetic skills in kindergarten and first grade.

Conclusion: This study shows how a genetic factor which has been shown to relate to variation in attention and regulatory behavior can explain delays in alphabetic skills. A practical implication is that in many cases early interventions should not only target reading skills, but also support children's engagement in tasks.