Abstract
BackgroundPrevious evidence supports the role of noradrenergic systems in ADHD, and norepinephrine transporter (NET) is critical in regulating the noradrenergic system. The present study aimed to investigate the association between NET gene polymorphism and the performance measures of the Continuous Performance Test (CPT) in Korean ADHD children.MethodsEighty-seven children (mean age = 9.23 ± 1.99 years) with ADHD were recruited from a university hospital. Genotypes of G1287A of the NET gene (SLC6A2) were analyzed. All participants completed the CPT, with performance measures of omission errors, commission errors, reaction time and reaction standardization computed. The relationship between G1287A polymorphisms and CPT performance measures was examined.ResultsThere were 46 subjects with the G/G genotype, 35 subjects with the G/A genotype and 6 subjects with the A/A genotype. Among the three groups, there were no significant differences in the performance of CPTs. When dichotomized according to whether the subjects have the rare allele or not, subjects with the homozygous G/G genotype showed significantly lower commission errors compared to those without G/G genotypes (by independent T-test, t = -2.18, p = 0.026).DiscussionOur study found a significant association between commission errors of the CPT and the G1287A genotype of the NET gene in Korean ADHD children. These findings suggest a protective role of the G/G genotype of the NET polymorphisms in the deficits of response inhibition in ADHD children.
Highlights
Previous evidence supports the role of noradrenergic systems in ADHD, and norepinephrine transporter (NET) is critical in regulating the noradrenergic system
Comparison of the Continuous Performance Test (CPT) performance between the subjects with and without G/G genotype Among the three SLC6A2 genotype groups, there were no significant differences in the performance of CPTs
Our study found a significant association between commission errors of the CPT and the NET G1287A genotype in Korean ADHD children
Summary
Previous evidence supports the role of noradrenergic systems in ADHD, and norepinephrine transporter (NET) is critical in regulating the noradrenergic system. The test assesses several measures including sustained attention in response to target stimuli and inhibitory control in response to non-target stimuli These measures are continuously quantifiable and probabilistically predictive of ADHD [8], with recent meta-analytic review reporting that the CPT measures possess the largest effect size for the diagnosis of ADHD [9]. A number of studies that investigated the genetic basis of CPT have mostly focused on dopaminergic genes such as the dopamine D4 receptor gene [10,11], the dopamine D5 receptor gene [12] and the dopamine transporter gene [13] In these studies, variants of the different dopaminergic genes have been associated with measures of inhibitory control and response time variability on CPT performance. The investigation of the effects of the noradrenergic system has been relatively scarce
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