Running head: NMDA receptor genes and CPT in ADHD
Abstract
Background: Previous genetic studies have reported an association between attention-deficit/hyperactivity disorder (ADHD) and N-methyl-D-aspartate (NMDA) receptor genes. However, the neuropsychological impacts of NMDA genes in ADHD have not been identified. We examined the association between two NMDA receptor subunit-encoding genes (GRIN2A and GRIN2B) and continuous performance test (CPT) variables in ADHD and healthy controls.
Methods: A total of 253 ADHD patients and 98 healthy controls aged 6–17 years were recruited, and a Korean version of the CPT was administered to all participants. Each polymorphism was dichotomized into two groups, and the diagnosis, gene, and diagnosis-gene interaction effects on the CPT variables were examined after adjusting for age, sex and IQ.
Results: Significant differences were detected between the ADHD and control group with regard to all CPT variables (p values < 0.05). There were significant genotype effects on omission errors (p = 0.039) and response time standard deviations (p = 0.001) by GRIN2B variants and on omission errors (p = 0.00) and response time standard deviations (p=0.049) by GRIN2A variants. The GRIN2B C/C genotype group had committed more omission errors (p = 0.005) and had higher response time standard deviation (p < 0.001) scores than the C/T + T/T group in ADHD, but this association was not found in controls. The C/C genotype showed a longer response time only in the control group (p = 0.002). Omission errors differed according to GRIN2A genotype (with more impairment with the G/G genotype) in ADHD patients (p < 0.001), but not in controls.
Conclusion: These results suggest that the genetic variants of the GRIN2B and GRIN2A genes confer an increased susceptibility to attentional impairment in ADHD patients.