ADHD candidate gene (DRD4 exon III) affects inhibitory control in a healthy sample
Ulrike M Krämer1, Nuria Rojo, Rebecca Schüle
1Dept, of Neuropsychology, Otto-von-Guericke-University, Magdeburg, Germany. ulrike.kraemer@ovgu.de
BMC Neuroscience
|December 22, 2009
Summary
Individuals with the dopamine D4 receptor (DRD4) 7-repeat gene variant show enhanced cognitive control and prefrontal function. This suggests a role for DRD4 in attention-deficit/hyperactivity disorder (ADHD) related neurophysiology.
Area of Science:
- Neuroscience
- Genetics
- Cognitive Psychology
Background:
- Dopamine is a key neurotransmitter implicated in attention-deficit/hyperactivity disorder (ADHD).
- The dopamine D4 receptor (DRD4) gene, particularly its 7-repeat variant, is associated with increased ADHD risk.
- This study investigates the neurophysiological impact of the DRD4 VNTR polymorphism in healthy individuals.
Purpose of the Study:
- To examine the influence of the DRD4 gene polymorphism on neurophysiological measures of response inhibition.
- To assess cognitive performance in relation to DRD4 7-repeat and 4-repeat variants during a Go/Nogo task.
Main Methods:
- Utilized a Go/Nogo task to evaluate response inhibition.
- Analyzed electroencephalography (EEG) data, focusing on theta and beta band activity.
- Compared neurophysiological correlates between homozygous 7-repeat and 4-repeat DRD4 genotype carriers.
Main Results:
- Homozygous 7-repeat carriers demonstrated a trend towards more accurate performance on the Go/Nogo task.
- An increased theta band response during 'nogo' trials was observed in 7-repeat carriers.
- A reduced beta band decrease during 'go' trials was noted in 7-repeat carriers.
Conclusions:
- The DRD4 7-repeat polymorphism is associated with enhanced cognitive functions and prefrontal control.
- These findings suggest a modulatory role of the D4 receptor in prefrontal areas impacting cognitive performance.
- Results align with previous behavioral and animal studies on the DRD4 receptor's cognitive effects.
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