Report from the third international meeting of the Attention-Deficit Hyperactivity Disorder Molecular Genetics Network

A Quantitative Comparison Approach for Methylphenidate Drug Regimens in Attention-Deficit/Hyperactivity Disorder Treatment

OBJECTIVE

Different methylphenidate (MPH) formulations, immediate release (IR) or extended release (ER), have been developed to treat Attention-Deficit/Hyperactivity Disorder (ADHD). A better use of these formulations, with a proper choice of their timing, dosage, and combination, can help to attain optimal therapeutic effect while maintaining a good quality of life. In this study, we aim at presenting a quantitative comparison approach to help identify drug regimens that provide best therapeutic performances and respect patients' specific needs.

METHODS

Using pharmacokinetic (PK) models of various MPH formulations constructed with data in hand and a formerly developed performance metric for MPH regimens, we proposed a statistical integral strategy for regimen comparison, which comprises a sequential, a relative, and a probability-over-threshold method. The first is hierarchical in nature and sequentially compares the regimen performance, the total daily dose, and the administration frequency. The second compares two regimens by quantifying their similarity. The third computes the probability of an incremental regimen performance over a specified threshold. The first two comparison approaches are used for naive patients, whereas the third one is for patients under treatment.

RESULTS

PK models of one compartment effectively describe both the IR and ER data. Applied to three frequent MPH clinical situations, the three-methods strategy is able to distinguish the regimens proposed for each. A combined regimen of IR and ER taken at the same time performs better than a single ER dose.

CONCLUSION

The proposed statistical strategy is able to differentiate ADHD regimens in various clinically relevant situations, and adapt the use of MPH drugs to a patient's daily routine. Since it does not compare fixed doses and formulations but rather any MPH regimen, our approach generalizes the current context of bioequivalence study and provides an accessible computational tool for objectively selecting MPH regimens.

Healthcare Utilization and Morbidity among Adolescents with ADHD in Children Aged 11-17 Years, NHIS, 2017

Purpose. Children with ADHD have known behaviors of hyperactivity and impulsivity which may result in adverse outcomes. The purpose of this study is to examine the association of serious adverse outcomes (emergency department visits within the previous year) in preadolescents and adolescents with ADHD as compared with preadolescents and adolescents without ADHD. Method. The researchers conducted a cross-sectional, secondary data analysis of National Health Interview Survey (NHIS) 2017 data concerning 2,965 children (>11 to 17 years). The NHIS data resulted from face-to-face interviews of a household member selected from a multistage area probability design representing households in the US. Data analyses for this study included Chi-square bivariate analyses and logistic regression analyses. Results. There were 13.2% of children in the sample who had ADHD. Children with ADHD were more likely to be male and non-Hispanic white. They were also more likely to have one or more additional disease or condition excluding ADHD. In adjusted logistic regression analysis on emergency department utilization by ADHD status, the adjusted odds ratio was 1.93 (95%CI: 1.35, 2.74; p = 0.0003) for preadolescents and adolescents with ADHD as compared with preadolescents and adolescents without ADHD. Conclusion. Children with ADHD were more likely to have emergency department utilization than children without ADHD. Preventive medical visits were similar between preadolescent and adolescent children with and without ADHD. Characteristics associated with ADHD may explain the increased need for emergent care. Developing interventions for children with ADHD may decrease emergency department utilization.

Oral Health of Children and Adolescents with Attention Deficit Hyperactivity Disorder

Aim

The aim of the study was to evaluate the oral health conditions of children and adolescents with attention deficit hyperactivity disorder (ADHD).

Materials and methods

Two groups were selected: a test group comprising 51 individuals with ADHD and a control group with 50 individuals without ADHD, with ages ranging from 7 to 14 years. Through an intraoral clinical examination, the numbers of decayed, missing, and filled teeth (DMFT index), the visible plaque index (VPI), the gingival bleeding index (GBI), bruxism, and dental traumatism were verified. A questionnaire confirmed oral hygiene supervision.

Results

In the test group, the average DMFT index was 3.41 while it was 2.52 in the control group (p = 0.405). The VPI in the test and control groups was 36.84% and 24.54%, respectively (p = 0.004). The GBI was 8.37% for the test group and 4.94% for the control group (p = 0.012). The DMFT index when supervised the oral hygiene by those responsible in comparison with the nonsupervision was 1.89 and 4.31, respectively, in the test group, and 1.71 and 2.94, respectively, in the control group.

Conclusion

These data suggest that children and adolescents with ADHD present with worse oral health conditions and need greater attention from dental professionals and those responsible for their diet and oral hygiene.

Clinical significance

Attention deficit hyperactivity disorder needs a special attention. This research brings this important issue focus on oral health.

How to cite this article

Begnini GJ, Brancher JA, Guimarães ATB, et al. Oral Health of Children and Adolescents with Attention Deficit Hyperactivity Disorder. Int J Clin Pediatr Dent 2019;12(6):543–547.

Multicenter analysis of the SLC6A3/DAT1 VNTR haplotype in persistent ADHD suggests differential involvement of the gene in childhood and persistent ADHD

Attention deficit/hyperactivity disorder (ADHD) is one of the most common neuropsychiatric disorders with a worldwide prevalence around 4-5% in children and 1-4% in adults. Although ADHD is highly heritable and familial risk may contribute most strongly to the persistent form of the disorder, there are few studies on the genetics of ADHD in adults. In this paper, we present the first results of the International Multicentre Persistent ADHD Genetics CollaboraTion (IMpACT) that has been set up with the goal of performing research into the genetics of persistent ADHD. In this study, we carried out a combined analysis as well as a meta-analysis of the association of the SLC6A3/DAT1 gene with persistent ADHD in 1440 patients and 1769 controls from IMpACT and an earlier report. DAT1, encoding the dopamine transporter, is one of the most frequently studied genes in ADHD, though results have been inconsistent. A variable number tandem repeat polymorphism (VNTR) in the 3'-untranslated region (UTR) of the gene and, more recently, a haplotype of this VNTR with another VNTR in intron 8 have been the target of most studies. Although the 10/10 genotype of the 3'-UTR VNTR and the 10-6 haplotype of the two VNTRs are thought to be risk factors for ADHD in children, we found the 9/9 genotype and the 9-6 haplotype associated with persistent ADHD. In conclusion, a differential association of DAT1 with ADHD in children and in adults might help explain the inconsistencies observed in earlier association studies. However, the data might also imply that DAT1 has a modulatory rather than causative role in ADHD.

Are endophenotypes based on measures of executive functions useful for molecular genetic studies of ADHD?

BACKGROUND

Behavioral genetic studies provide strong evidence that attention-deficit/hyperactivity disorder (ADHD) has a substantial genetic component. Yet, due to the complexity of the ADHD phenotype, questions remain as to the specific genes that contribute to this condition as well as the pathways from genes to behavior. Endophenotypes, or phenotypes that are more closely linked to the neurobiological substrate of a disorder, offer the potential to address these two issues simultaneously (Freedman, Adler, & Leonard, 1999). Thus far, potential endophenotypes for ADHD have not been systematically studied.

METHOD

The current paper reviews evidence supporting the use of deficits on neurocognitive measures of executive functions for this purpose.

RESULTS

Such deficits are a correlate of ADHD and show preliminary evidence of heritability and association with relevant candidate genes. Nonetheless, studies that have assessed the familial and genetic overlap of neurocognitive impairments with ADHD have yielded inconsistent results.

CONCLUSIONS

In order for executive function deficits to be used as an endophenotype for ADHD, we recommend greater attention to the neurocognitive heterogeneity of this disorder and to the precision of measurement of the neuropsychological tests employed. We also discuss empirical strategies that may be necessary to allow such research to progress prior to full resolution of the pathophysiological basis of ADHD.

Attention-deficit/hyperactivity disorder endophenotypes

Attention-deficit/hyperactivity disorder (ADHD) is a highly heritable disorder with a multifactorial pattern of inheritance. For complex conditions such as this, biologically based phenotypes that lie in the pathway from genes to behavior may provide a more powerful target for molecular genetic studies than the disorder as a whole. Although their use in ADHD is relatively new, such "endophenotypes" have aided the clarification of the etiology and pathophysiology of several other conditions in medicine and psychiatry. In this article, we review existing data on potential endophenotypes for ADHD, emphasizing neuropsychological deficits because assessment tools are cost effective and relatively easy to implement. Neuropsychological impairments, as well as measures from neuroimaging and electrophysiological paradigms, show correlations with ADHD and evidence of heritability, but the familial or genetic overlap between these constructs and ADHD remains unclear. We conclude that these endophenotypes will not be a quick fix for the field but offer potential if careful consideration is given to issues of heterogeneity, measurement and statistical power.

Familial clustering of executive functioning in affected sibling pair families with ADHD

OBJECTIVE

To investigate familial clustering of executive functioning (i.e., response inhibition, fine visuomotor functioning, and attentional control) in attention-deficit/hyperactivity disorder (ADHD)-affected sibling pairs.

METHOD

Fifty-two affected sibling pairs aged 6 to 18 years and diagnosed with ADHD according to DSM-IV performed the Stroop test, go/no-go task, two different fine visuomotor tracking tasks, and a sustained-, divided-, and focused attention task.

RESULTS

Significant correlations (r = 0.4) were found between siblings for response inhibition and attentional control and for fine visuomotor skills that made high demands on executive functioning.

CONCLUSIONS

Response inhibition, higher order controlled fine visuomotor functioning, and attentional control seem to cluster in ADHD-affected siblings. This suggests that these aspects of executive dysfunctioning may reflect an endophenotype of ADHD. Measurement of these executive functions may facilitate the identification of genes involved in ADHD by forming more homogeneous subgroups.

Attention-deficit/hyperactivity disorder and comorbidities in 18 Paisa Colombian multigenerational families

OBJECTIVE

Eighteen extended multigenerational families were recruited from the genetically isolated Paisa community in Colombia to conduct genetic studies of attention-deficit/hyperactivity disorder (ADHD). This report describes the inclusion strategy and clinical features of participants to facilitate comparisons with other data sets.

METHOD

Families were selected through a fixed-sampling scheme beginning with child probands referred for clinical evaluation for ADHD. Direct structured psychiatric interviews were conducted with 433 informative individuals, including 92 children aged 4 to 11, 57 adolescents aged 12 to 17, and 284 adults. Best estimate ADHD diagnoses were established for each informative pedigree member.

RESULTS

These families contained a high proportion of individuals affected with ADHD (32.8%), which was highly comorbid with conduct disorder (50%; odds ratio 11.5, 95% confidence interval = 6.4-20.9), oppositional defiant disorder (25.4%; odds ratio 2.7, confidence interval = 1.5-4.8), and associated conditions including nicotine dependence and alcohol abuse and/or dependence.

CONCLUSIONS

ADHD in these extended Paisa families is highly comorbid with conduct and oppositional defiant disorders. This pattern of comorbidity, as well as the large dense pedigrees of the sample, suggests that it will be particularly useful for molecular genetic studies that are currently under way.

Attention deficit/hyperactivity disorder (ADHD): complex phenotype, simple genotype?

Complex genetic traits refer to those phenotypes not fitting patterns of Mendelian segregation and/or assortment but exhibiting a preferential familial clustering that cannot be explained by cultural or environmental causes. Attention-deficit/hyperactivity disorder (ADHD) is the most common neurodevelopmental disorder of childhood and probably the most controversial. ADHD has been considered a complex genetic trait based upon the absence of a clear-cut boundary between affected and unaffected status. Furthermore, its high comorbidity with other disorders strongly suggests complex epistatic or pleiotropic effects acting in common with the environmental influences. This implies that the same gene or genes is or are associated with different and concurrently occurring phenotypes. In this study, we will review clinical and epidemiological aspects related to the ADHD phenotype, which are considered either as categorical or continuous traits. We also will discuss genetic models underlying the complexity of this behavioral phenotype and the probable role of epistatic interactions between major genes contributing to the ADHD phenotype.

Report from the 4th international meeting of the attention deficit hyperactivity disorder molecular genetics network

Investigators from around the world have convened annually since 1999 to share their work on the molecular genetic basis of attention deficit hyperactivity disorder (ADHD). The 4th meeting of the ADHD Molecular Genetics Network was held in May 2002. This conference began with a discussion of ongoing and proposed collaborative projects. Ongoing collaborations include the International Multi-Center ADHD Genetics (IMAGE) project, a study of additive and interactive effects of DAT1 and DRD4 on ADHD and a meta-analysis of association studies of ADHD and the DRD5 gene. A new collaborative project regarding DNA pooling was also proposed. Over 20 investigators presented recent findings from their individual research sites. Participants also broke up into working groups to discuss additional projects and topics of mutual interest, including population genetic studies using dimensional phenotypic data and a QTL approach, endophenotypes for ADHD and the genetics of ADHD in adults. Finally, participant feedback was obtained about the utility of the ADHD Molecular Genetics Network conferences and the e-mail network. Although technological and statistical advances in the field of molecular genetics have allowed researchers to begin to identify specific genes that are associated with ADHD, continued collaborative efforts are needed to fully elucidate the genetic underpinnings of this complex phenotype. Data collected at the current conference indicate that the ADHD Molecular Genetics Network has facilitated new collaborative as well as single-site projects among ADHD researchers.