Search

Background: Methylphenidate (MPH) blocks the norepinephrine transporter as well as the dopamine transporter. The α-2a-adrenergic receptor is a key component of the noradrenergic system. The aim of this study was to evaluate the association between the ADRA2A -1291 C>G polymorphism and the response to MPH treatment in Korean subjects with attention-deficit/hyperactivity disorder (ADHD). Methods: This study enrolled 114 ADHD children (mean age = 9.08 ± 1.94 years) from a child psychiatric clinic in South Korea. Subjects who had an improvement of ≥ 50% compared with the baseline ADHD rating scale (ARS) score or who had a Clinical Global Impression–improvement score of 1 or 2 points after treatment were defined as the “good response”. We examined the relationship of the ADRA2A to MPH response. Results: We found that a good response to MPH treatment, measured by the ARS as assessed by the parents, was observed for 76.9% of the subjects carrying the G/G genotype but for only 46.0% and 41.7% of those with the C/G and C/C genotypes, respectively [χ 2(2) = 11.929, p = .003]. We also found a significant difference in the change in total ARS scores between subjects with and without the G/G genotype [t(1) = 2.21, p = .029]. Conclusions: Our findings provide evidence of an association between the ADRA2A -1291 C>G genotype and response to MPH treatment in Korean subjects with ADHD. Nonetheless, the methodological limitation of not being a randomized placebo-controlled trial and primarily basing results on parent report to clinicians suggest that these results should be viewed as more preliminary. [Copyright &y& Elsevier]

It has been suggested that dopamine, as well as serotonin, is associated with the pathophysiology of obsessive-compulsive disorder (OCD). Thus, many studies have been performed on brain regions associated with dopamine in patients with OCD. In the present study, we investigated the DAT density of the basal ganglia using iodine-123 labelled N-(3-iodopropen-2-yl)-2β-carbomethoxy-3β-(4-chlorophenyl) tropane ([123I]IPT) single-photon emission tomography (SPET) and evaluated the activity of the presynaptic dopamine function in patients with OCD. Fifteen patients with OCD and 19 normal control adults were included in the study. We performed brain SPET 2 h after the intravenous administration of [123I]IPT and carried out both quantitative and qualitative analyses using the obtained SPET data, which were reconstructed for the assessment of the specific/non-specific dopamine transporter (DAT) binding ratio in the basal ganglia. We then investigated the correlation between the severity scores of OCD symptoms assessed with the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) and the specific/non-specific DAT binding ratio of the basal ganglia. Compared with normal control adults, patients with OCD showed a significantly increased specific/non-specific DAT binding ratio in the right basal ganglia and a tendency towards an increased specific/non-specific DAT binding ratio in the left basal ganglia. No significant correlation was found between the total scores on the Y-BOCS and the specific/non-specific DAT binding ratio of the basal ganglia. These findings suggest that the dopaminergic neurotransmitter system of the basal ganglia in patients with OCD could be involved in the pathophysiology of OCD. [ABSTRACT FROM AUTHOR]

Attention deficit hyperactivity disorder (ADHD) is a psychiatric disorder in childhood that is known to be associated with dopamine dysregulation. In this study, we investigated dopamine transporter (DAT) density in children with ADHD using iodine-123 labelled N-(3-iodopropen-2-yl)-2β-carbomethoxy-3β-(4chlorophenyl) tropane ([[sup 123]I]IPT) single-photon emission tomography (SPET) and postulated that an alteration in DAT density in the basal ganglia is responsible for dopaminergic dysfunction in children with ADHD. Nine drug-naive children with ADHD and six normal children were included in the study. We performed brain SPET 2 h after the intravenous administration of [[sup 123]I]IPT and carried out both quantitative and qualitative analyses using the obtained SPET data, which were reconstructed for the assessment of the specific/non-specific DAT binding ratio in the basal ganglia. We then investigated the correlation between the severity scores of ADHD symptoms in children with ADHD assessed with ADHD rating scale-IV and the specific/non-specific DAT binding ratio in the basal ganglia. Drug-naive children with ADHD showed a significantly increased specific/nonspecific DAT binding ratio in the basal ganglia compared with normal children. However, no significant correlation was found between the severity scores of ADHD symptoms in children with ADHD and the specific/nonspecific DAT binding ratio in the basal ganglia. Our findings support the complex dysregulation of the dopaminergic neurotransmitter system in children with ADHD. [ABSTRACT FROM AUTHOR]

Abstract: Although the etiology of Attention Deficit/Hyperactivity Disorder (ADHD) is not well understood, evidence from the family and twin studies suggest that ADHD is familial and highly heritable. The aim of the study was to test whether dopamine transporter gene (DAT1) and dopamine receptor D4 gene (DRD4) polymorphisms are in linkage disequilibrium with ADHD in Korean children, using a family-based association study. One hundred and twenty-six trios were studied and 87% of probands were boys (mean age=8.2 years, mean IQ=104). ADHD not otherwise specified (NOS) was the most common subtype and comorbidity rates were low. Descriptive analysis and the TDT test were the primary analyses. In exploratory analyses, logistic regression and QTDT were performed. The 10-repeat allele and 4-repeat allele were the most frequent for DAT1 and DRD4. TDT test for DAT1 and DRD4 did not show preferential transmission. Based on logistic regression and QTDT, the 5-repeat allele of DRD4 may confer protection for hyperactive-impulsivity symptom severity compared to the 4-repeat allele. The negative TDT finding between DAT1 and DRD4 VNTR polymorphisms and ADHD should be interpreted with caution; partly due to lack of power caused by low heterozygosity in the study population. Future studies are necessary to test the hypothesis generated in this study that the 5-repeat allele of DRD4 is protective for hyperactive-impulsivity symptom severity compared to the 4-repeat allele. [Copyright &y& Elsevier]