ADHD: relation between cognitive characteristics and DAT1 / DRD4 dopamine polymorphisms

Attention deficit hyperactivity disorder (ADHD) is a clinical and diagnostic heterogeneous picture. This study analysed the association of functional polymorphisms in DAT1 VNTR 3 UTR and DRD4 VNTR Exon III candidate genes, and the neuropsychological characterisation of attention and executive functions of a group of children with ADHD vs. controls. 32 patients and 51 controls were selected. The DAT1 10-repeat allele appeared more frequently in the two groups (cases: 0.93/control: 0.82), showing an OR: 2.5 (IC 95%: 0.684-9.133; p: 0.158). In DRD4, the 4-repeat allele shows the highest occurrence (cases: 0.62/controls: 0.60). None of the markers presented a significant association after a direct analysis, but the DRD4 7-repeat marker showed a positive risk when performing a Bayesian logistic analysis (coefficient: -1.69; OR: 5.39 CI 95%: 1.167-40.97). On the other hand, when considering association with cognitive performance, a positive risk for processing speed and attention tasks was identified.