Standard scores were used for all WCST and TOL measures, and T scores were used for CPT measures (excluding overall index). Solid colour indicates under-transmission of the risk allele (C*). Striped colour indicates over-transmission of the rs1329650 risk allele. Risk alleles are under-transmitted (negative Z score, solid boxes) to the higher scores (the higher standard scores imply a better performance on the test). Lower WCST standard scores indicate worse performance. Risk alleles were associated with poorer performance on the SOPT and CPT. Since these are not standardised scores, the higher SOPT total score and CPT T scores indicate worse performance.

ADHD, attention-deficit hyperactivity disorder; CPT, Continuous Performance Test; RT, reaction time; SNP, single nucleotide polymorphism; SOPT, Self-Ordered Pointing Task; TOL, Tower of London; WCST, Wisconsin Card Sorting Test; WISC, Wechsler Intelligence Scale.