No evidence for the association of DRD4 with ADHD in a Taiwanese population within-family study

BACKGROUND: Attention Deficit Hyperactivity Disorder (ADHD) is a prevalent and highly heritable childhood disorder. The dopamine D4 receptor (DRD4) gene has shown a genetic association with ADHD in Caucasian populations with meta-analysis indicating a small but significant effect across datasets. It remains uncertain whether this association can be generalised to non-Caucasian ethnic groups. Here we investigate two markers within the DRD4 gene in a Taiwanese population, the exon 3 variable number tandem repeat (VNTR) and a 5' 120 base-pair duplication. METHODS: Within-family transmission disequilibrium tests of association of the 5' 120 base-pair duplication, and exon 3 VNTR in a Taiwanese population. RESULTS: No evidence of association of ADHD with either polymorphism in this population was observed. CONCLUSION: The DRD4 gene markers investigated were not found to be associated with ADHD in this Taiwanese sample. Further work in Taiwanese and other Asian populations will therefore be required to establish whether the reports of association of DRD4 genetic variants in Caucasian samples can be generalised to Asian populations

Long-Term Activity-Dependent Plasticity of Action Potential Propagation Delay and Amplitude in Cortical Networks

Background: The precise temporal control of neuronal action potentials is essential for regulating many brain functions. From the viewpoint of a neuron, the specific timings of afferent input from the action potentials of its synaptic partners determines whether or not and when that neuron will fire its own action potential. Tuning such input would provide a powerful mechanism to adjust neuron function and in turn, that of the brain. However, axonal plasticity of action potential timing is counter to conventional notions of stable propagation and to the dominant theories of activity-dependent plasticity focusing on synaptic efficacies. Methodology/Principal Findings: Here we show the occurrence of activity-dependent plasticity of action potentia

Epilepsy and attention deficit hyperactivity disorder:Is methylphenidate safe and effective? (vol 130, pg 40, 1997)

Objective: To study the safety and efficacy of methylphenidate in children with the dual diagnosis of epilepsy and attention deficit hyperactivity disorder (ADHD). Study design: Thirty children, aged 6.4 to 16.4 years, with epilepsy and ADHD were studied during a 4-month period. During the initial 2 months of the study, the children were treated with antiepileptic drugs (AEDs) only, and for the remaining 2 months, methylphenidate was added at a morning dose of 0.3 mg/kg. They underwent neurologic assessment, brain computed tomography, IQ testing, and assessment with the Childhood Behavior Checklist at baseline before methylphenidate therapy. Electroencephalography, AED determinations, and the continuous-performance task (CPT) test were done at baseline and after 2 months of methylphenidate therapy. A double-blind, crossover design was used to compare the effects of methylphenidate versus placebo on an electroencephalogram, AED levels, and the CPT. On the 2 days of testing, the child received AEDs and a capsule containing either placebo or methylphenidate. Results: None of the 25 children of this sample who were seizure free had attacks while taking methylphenidate. Of the 5 children with seizures, 3 had an increase in attacks, whereas the other 2 showed no change or a reduction. There were no significant changes in AED levels or electroencephalographic findings. Methylphenidate benefited 70% of children according to parental report; methylphenidate also enhanced performance on the CPT. Side effects of methylphenidate were mild and transient, Conclusion: Methylphenidate is effective in treating children with epilepsy and ADHD and safe in children who are seizure free. Caution is warranted for those still having seizures while receiving AED therapy