ADHD candidate gene (DRD4 exon III) affects inhibitory control in a healthy sample.
BACKGROUND
Dopamine is believed to be a key neurotransmitter in the development of attention-deficit/hyperactivity disorder (ADHD). Several recent studies point to an association of the dopamine D4 receptor (DRD4) gene and this condition. More specifically, the 7 repeat variant of a variable number of tandem repeats (VNTR) polymorphism in exon III of this gene is suggested to bear a higher risk for ADHD. In the present study, we investigated the role of this polymorphism in the modulation of neurophysiological correlates of response inhibition (Go/Nogo task) in a healthy, high-functioning sample.


RESULTS
Homozygous 7 repeat carriers showed a tendency for more accurate behavior in the Go/Nogo task compared to homozygous 4 repeat carriers. Moreover, 7 repeat carriers presented an increased nogo-related theta band response together with a reduced go-related beta decrease.


CONCLUSIONS
These data point to improved cognitive functions and prefrontal control in the 7 repeat carriers, probably due to the D4 receptor's modulatory role in prefrontal areas. The results are discussed with respect to previous behavioral data on this polymorphism and animal studies on the impact of the D4 receptor on cognitive functions.
Krämer
Ulrike M
UM
Dept, of Neuropsychology, Otto-von-Guericke-University, Magdeburg, Germany. ulrike.kraemer@ovgu.de
Rojo
Nuria
N
Schüle
Rebecca
R
Cunillera
Toni
T
Schöls
Ludger
L
Marco-Pallarés
Josep
J
Cucurell
David
D
Camara
Estela
E
Rodriguez-Fornells
Antoni
A
Münte
Thomas F
TF
D000293:Adolescent; D000328:Adult; D001289:Attention Deficit Disorder with Hyperactivity / Q000235:genetics*; D003071:Cognition / Q000502:physiology; D005071:Evoked Potentials; D005260:Female; D005838:Genotype; D006579:Heterozygote; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D008875:Middle Aged; D018598:Minisatellite Repeats; D011110:Polymorphism, Genetic; D017397:Prefrontal Cortex / Q000503:physiopathology*; D050638:Receptors, Dopamine D4 / Q000378:metabolism*; D012016:Reference Values; D055815:Young Adult
C493599:DRD4 protein, human; D050638:Receptors, Dopamine D4