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The 48-basepair (48-bp) variable number tandem repeat (VNTR) polymorphism in exon 3 of the dopamine receptor D4 gene (DRD4) is implicated in the etiology of attention-deficit/ hyperactivity disorder (ADHD). In particular, ADHD in European-ancestry population is associated with an increased prevalence of the 7-repeat (7R) allele of the exon 3 VNTR. However, it is intriguing to note that the 7R allele has been found to be of very low prevalence in the Chinese general population. In a previous case-control study, our research team had found that the 7R allele was similarly absent in Chinese ADHD children in Hong Kong. Instead, there was an increased prevalence of the 2R allele in Chinese ADHD children. Interestingly, in Asian samples, the 2R allele had been found to be an evolutionary derivative of the 7R allele with equivalent biochemical functionality. So, the finding of an association between ADHD and 2R allele in Chinese population does not exactly contradict the original 7R allele finding in European-ancestry population. However, given the potential pitfall of population stratification in the previous case-control design, this current study tested the 2R allele and ADHD association using a methodologically more rigorous family-based approach on 33 Chinese ADHD probands who had favorable clinical responses to stimulant medication (methylphenidate). Haplotype Relative Risk (HRR) analysis and Transmission Disequilibrium Test (TDT) both showed a significant preferential transmission of the 2R allele from the biological parents to ADHD probands (pone-tailed = 0.038, OR = 2.04; pone-tailed = 0.048, OR = 2.29, respectively). A second hypothesis speculates that it is the deviation, including 7R and 2R alleles, from the conserved ancestral 4R allele which confers risk to ADHD. Thus, a preferential transmission of non-4R alleles, against the 4R allele, from biological parents to their ADHD probands is predicted. Both HRR analysis and TDT confirmed such prediction (pone-tailed = 0.029, OR = 2.07; pone-tailed = 0.032, OR = 2.43, respectively). This study re-confirmed the original finding of a previous study that in Chinese population, the 2R allele of the DRD4 exon 3 VNTR was related to ADHD. This endorses the general thesis that DRD4 exon 3 VNTR polymorphism is related to ADHD, despite that the exact length or number of repeats of the associated alleles varies across ethnicity. This in turn supports the dopamine dysregulation theory of ADHD.

Background: Recent findings indicated a high comorbidity between attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD), as well as shared genetic influences on them. The latter might contribute at least partly to the former clinical scenario. This study aimed at investigating whether SHANK genes were potential pleiotropic genes to the two said disorders, underlying their genetic overlap.Methods: This study recruited 298 boys with ADHD (including 256 family trios of 1 ADHD boy and his 2 biological parents), 134 boys with ASD, 109 boys with both ADHD and ASD, and 232 typically developing boys as community controls. They were aged between 6 and 11 years old.Results: There was no significant difference in allele frequency of a number of single nucleotide polymorphisms (SNPs) in SHANK2/SHANK3 between the three clinical groups (ADHD, ASD, and ADHD + ASD) and between the two control groups (community controls and pseudo-controls), respectively. The three clinical groups and the two control groups were thus, respectively, combined. A comparison between the two aggregated samples identified significant evidence of disease association for three SHANK2 SNPs with both ADHD and ASD, even after multiple testing correction: rs11236616 (OR = 0.762, permuted p = 0.0376), rs7106631 (OR = 0.720, permuted p = 0.0034), and rs9888288 (OR = 0.770, permuted p = 0.0407). Comparisons among individual groups pointed to a similar trend of findings.Conclusion:SHANK2 could be considered a potential pleiotropic gene underlying the genetic overlap between ADHD and ASD. This might contribute partly to their high comorbidity in the afflicted children.

The development of the Chinese version of Diagnostic Interview Schedule for Children-Version 4 (DISC-IV) is reported and its test-retest reliability is examined. One of the findings suggests that parent informants had better test reliability than youth informants.

Background: Methylphenidate (MPH) has been found to be an effective medication for attention-deficit/hyperactivity disorder (ADHD). However, there are neither consistent nor sufficient findings on whether psychiatric comorbidities and associated cognitive functions of ADHD are related to treatment response to MPH in ADHD children. Objectives: This study investigated whether psychiatric comorbidities, IQ, and neurocognitive deficits are related to treatment response to MPH in ADHD children. In some ways, it is preferable to have a drug that the effectiveness of which to a disorder is not affected by its associated cognitive functions and psychiatric comorbidities. On the other hand, it is likely that the baseline symptom severity of ADHD is associated with the effectiveness of MPH treatment on the symptoms post treatment. Methods: A total of 149 Chinese boys (aged 6-12 years) with ADHD, combined type, and normal IQ participated in this study. Assessment of ADHD symptom severity was conducted pre and post MPH treatment, while assessment of psychiatric comorbidities, IQ, and neurocognitive deficits was performed in a non-medicated condition. Treatment response was defined as the ADHD symptom severity post MPH treatment. Results: Results indicated that MPH treatment was effective, significantly improving the ADHD condition. Yet, comorbid disorders, IQ, and neurocognitive deficits were not related to MPH treatment response on ADHD symptoms. These findings indicated that the effectiveness of MPH was not affected by psychiatric comorbidities and associated cognitive functions of ADHD. Instead, as expected, it was the baseline symptom severity that was mainly related to the treatment response, ie, the milder the baseline condition, the better the treatment response. Conclusion: The current findings positively endorse the widespread clinical use of MPH for treating ADHD. It improves the behavioral symptoms of ADHD regardless of varying psychiatric comorbidities, IQ, and neurocognitive deficits. [ABSTRACT FROM AUTHOR]

Background: Children with attention-deficit hyperactivity disorder (ADHD) have difficulties with executive function and impulse control which may improve with age.Aims: To map the brain correlates of executive function in ADHD and determine age-related changes in reaction times and brain volumes.Method: Attention-deficit hyperactivity disorder and control groups were compared on the change task measures of response inhibition (stop signal reaction time, SSRT) and shifting (change response reaction time, CRRT). Voxel-wise magnetic resonance imaging (MRI) correlations of reaction times and grey matter volume were determined, along with bivariate correlations of reaction times, brain volumes and age.Results: Individuals in the ADHD group had longer SSRTs and CRRTs. Anterior cingulate, striatal and medial temporal volumes highly correlated with SSRT. Striatal and cerebellar volumes strongly correlated with CRRT. Older children had faster reaction times and larger regional brain volumes. In controls, orbitofrontal, medial temporal and cerebellar volumes correlated with CRRT but not SSRT. Neither reaction times nor regional brain volumes were strongly age-dependent.Conclusions: Our evidence supports delayed brain maturation in ADHD and implies that some features of ADHD improve with age. [ABSTRACT FROM AUTHOR]

To provide preliminary prevalence estimates of common DSM-IV (Diagnostic and Statistical Manual of Mental Disorders—4th Edition) disorders in a sample of Hong Kong Chinese adolescents. 541 Chinese adolescents were recruited from Grades 7, 8 and 9 of 28 mainstream high schools in Hong Kong (mean age=13.8 years; SD=1.2). The adolescents and their parents were separately administered the Youth and Parent versions of DISC-IV (Diagnostic Interview Schedule for Children-Version 4), respectively. Based upon both symptom and impairment criteria, as required by DSM-IV, the overall prevalence estimate of DSM-IV disorders in our sample of Chinese adolescents was 16.4%. Estimates for such individual disorders/diagnostic groupings as anxiety disorders, depressive disorders, attention deficit/hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), conduct disorder (CD), and substance use disorders were 6.9, 1.3, 3.9, 6.8, 1.7, and 1.1%, respectively. These rates were largely compatible with those reported in previous studies with perhaps lower rates of generalized anxiety disorder (GAD), depressive disorders, CD, and substance use disorders, but a higher rate of ODD. The rate of ADHD was somewhat higher, but this might reflect the current DSM-IV diagnostic practice. The rate of anxiety disorders was not as high as predicted from some previous questionnaire surveys. The application of an impairment criterion had discernible impacts on prevalence estimates, greater on anxiety and substance use disorders, but smaller on depressive and disruptive behavior disorders. There was a lack of gender difference in rates of ODD and CD. While the findings reported here are broadly compatible with those of other studies, there may be cross-cultural differences in rates of some individual disorders, e.g., GAD, depressive disorders, ODD, CD, and substance use disorders, as well as in gender difference regarding rates of ODD and CD. However, exact comparison between studies is confounded by methodological differences in sample characteristics, measures, and case definition. Standardization of methodology in epidemiological surveys should allow more precise identification of any within- or between-culture variations in prevalence estimation. [ABSTRACT FROM AUTHOR]

The article examines the test-retest reliability and screening efficiency of DISC Predictive Scales-4.32 (DPS-4.32), short-forms of the Diagnostic Interview Schedule for Children-IV, with Chinese children/youths. The results of the study revealed that both Parent and Youth DPS-4.32 exhibited good-to excellent test-retest reliability. The study concluded that DPS-4.32 is an efficient short-forms of DISC-IV and applicable to the Chinese population.

A letter to the editor is presented in response to an article about a survey of referrals to the child unit of a department of psychiatry in a teaching hospital in Hong Kong, that was published in the March 1990 issue.