Association of high reaction time variability with the 7-repeat allele absence appears to be the most consistent result and seems to be specific to ADHD .
Speed of processing , set-shifting and cognitive impulsiveness were less frequently investigated but seem to be altered in the 7-repeat allele carriers .
High reaction time variability seems to be the most replicated cognitive marker associated with the 10-repeat homozygosity .
BACKGROUND We review ed systematic ally the results of genetic studies investigating associations between putative susceptibility genes for attention-deficit hyperactivity disorder ( ADHD ) and neuropsychological traits relevant for this disorder .
Covert visual spatial attention in boys with attention deficit hyperactivity disorder: Lateral effects, methylphenidate response and results for parents
We report three related studies of covert visual spatial orienting in child attention deficit hyperactivity disorder ( ADHD ) . In Study 1 , we examined covert visual spatial orienting in ADHD and comparison boys , Study 2 comprised a dose-response study of methylpheni date for the ADHD group , and Study 3 was an investigation of biological and adoptive parents . In contrast with comparison subjects ( n = 17 ) . ADHD boys aged 6 - 12 ( n = 27 ) showed both slower reaction times overall and within-condition ( lateral ) asymmetries in reaction times . Specifically , boys with ADHD  reacted more slowly to uncued targets in the left visual field than in the right visual field . Responses to stimuli in the two visual fields were differentially affected by methylpheni date for the ADHD group . Medication equalized visual field responses to the uncued targets , result ing in a significant cue x dose x visual field interaction . Further , medication altered the relative cue responsivity in the two visual fields , result ing in a significant dose x visual field interaction for the Validity Effect . Biological parents of ADHD boys ( n = 16 ) also showed slower reaction times to uncued left visual field targets than to right visual field targets ; in addition they showed slower response to invalidity cued targets in the right visual field . These literal effects were not observed in adoptive parents of ADHD boys ( n = 12 ) or biological parents of comparison boys ( n = 14 ) . Possible abnormal hemispheric asymmetry of attention functions in boys with ADHD and their biological parents is discussed
Association of high reaction time variability with the 7-repeat allele absence appears to be the most consistent result and seems to be specific to ADHD .
Speed of processing , set-shifting and cognitive impulsiveness were less frequently investigated but seem to be altered in the 7-repeat allele carriers .
High reaction time variability seems to be the most replicated cognitive marker associated with the 10-repeat homozygosity .
BACKGROUND We review ed systematic ally the results of genetic studies investigating associations between putative susceptibility genes for attention-deficit hyperactivity disorder ( ADHD ) and neuropsychological traits relevant for this disorder .