Estimation of Prevalence of DSM-IV and Latent Class-Defined ADHD Subtypes in a Population-Based Sample of Child and Adolescent Twins

Predictors of Attention Deficit Hyperactivity Disorder in Sri Lankan Children: A School Based Community Study

OBJECTIVE

To evaluate potential risk-factors of ADHD among primary school-children (PSC) in state schools in Colombo district of Sri Lanka.

METHOD

A case-control study was conducted with 73 cases and 264 controls selected randomly among 6 to 10-year-old PSC from Sinhala medium state schools in Colombo district. Primary care givers completed the SNAP-IV P/T-S scale to screen for ADHD and an interviewer-administered questionnaire on risk-factors. Children's diagnostic status was confirmed by a Consultant Child and Adolescent Psychiatrist based on DSM-5 criteria.

RESULTS

A binomial regression model identified male sex (aOR = 3.45; 95% CI [1.65, 7.18]), lower educational level of the mother (aOR = 2.99; 95% CI [1.31, 6.48]), birth weight <2,500 g (aOR = 2.83; 95% CI [1.17, 6.81]),a neonatal complications (aOR = 3.82; 95% CI [191, 7.65]) and child having witnessed verbal/emotional aggression between parents (aOR = 2.08; 95% CI [1.01, 4.27])as significant predictors of ADHD.

CONCLUSION

Primary prevention should focus on strengthening neonatal, maternal and child health services within the country.

Annual Research Review: The transdiagnostic revolution in neurodevelopmental disorders

Practitioners frequently use diagnostic criteria to identify children with neurodevelopmental disorders and to guide intervention decisions. These criteria also provide the organising framework for much of the research focussing on these disorders. Study design, recruitment, analysis and theory are largely built on the assumption that diagnostic criteria reflect an underlying reality. However, there is growing concern that this assumption may not be a valid and that an alternative transdiagnostic approach may better serve our understanding of this large heterogeneous population of young people. This review draws on important developments over the past decade that have set the stage for much-needed breakthroughs in understanding neurodevelopmental disorders. We evaluate contemporary approaches to study design and recruitment, review the use of data-driven methods to characterise cognition, behaviour and neurobiology, and consider what alternative transdiagnostic models could mean for children and families. This review concludes that an overreliance on ill-fitting diagnostic criteria is impeding progress towards identifying the barriers that children encounter, understanding underpinning mechanisms and finding the best route to supporting them.

The association between heightened ADHD symptoms and cytokine and fatty acid concentrations during pregnancy

OBJECTIVE

Previous research conducted with samples of children suggest that individuals with attention-deficit/hyperactivity disorder (ADHD) have altered fatty acid concentrations and may have increased systemic inflammation. Whether these differences are also apparent in other populations of individuals with heightened ADHD symptoms (e.g., pregnant adults) is unknown. The goal of the current study was to examine whether there are ADHD-associated differences in polyunsaturated fatty acid concentrations or pro-inflammatory cytokine concentrations during pregnancy, a developmental period when fatty acid concentrations and systemic inflammation have implications for the health of both the pregnant person and the developing child. We hypothesized that plasma levels of the ratio of omega-6s to omega-3s (n-6:n-3) and plasma inflammatory cytokine levels would be higher in individuals with heightened ADHD symptoms, consistent with previous findings in children with ADHD.

METHODS

Data (N = 68) came from a prospective study of pregnant community volunteers who were oversampled for ADHD symptoms. During the 3rd trimester, plasma concentrations of fatty acids and the pro-inflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) were assessed. Dietary intake was examined in the 3rd trimester using three 24-h recalls conducted by trained dietitians and by examining plasma levels of conjugated linoleic acid (n-6) and α-linolenic acid (n-3), essential fatty acids that must come from dietary intake.

RESULTS

The group with heightened ADHD symptoms had higher n-6:n-3s (β = 0.30, p < 0.01) and higher TNF-α concentrations (β = 0.35, p < 0.001) relative to controls. There were no group differences in dietary variables, as assessed by self-report and via plasma concentrations of essential fatty acids. IL-6 was not reliably associated with ADHD status in this sample.

CONCLUSION

Pregnant individuals with ADHD, on average, had higher plasma n-6:n-3s and higher TNF-α concentrations relative to controls. A difference was not detected in their dietary intake of fatty acids or other relevant nutrients. Though these null findings are inconclusive, they are consistent with the hypothesis that ADHD-associated differences in plasma fatty acid concentrations are the result of ADHD-associated differences in fatty acid metabolism, rather than simply differences in dietary intake.

Irritability Predicts Hyperactive/Impulsive Symptoms Across Adolescence for Females

Irritability is common in Attention-Deficit Hyperactivity Disorder (ADHD), but little is known about whether irritability predicts the course of ADHD symptoms over time. Adolescence is a dynamic period of emotional development as well as shifts in ADHD symptoms; an important goal is to identify youth at risk of increasing or persisting symptoms. We examined irritability as a longitudinal predictor of change in adolescents' ADHD symptoms, as well as how this link may differ in females versus males. The sample included 108 youth (72 males) age 12-16 years (M = 14.21 years, SD = 1.44 years), 62 of whom met criteria for ADHD. Approximately 18 months later, 80 participants (48 males) were followed up at Time 2. A dimensional approach was used to examine changes over time in parent-reported inattentive and hyperactive/impulsive symptoms. Longitudinal path analysis revealed that irritability at Time 1 predicted higher relative hyperactive/impulsive symptoms at Time 2 after controlling for age and longitudinal stability in all variables. A multiple-group analysis examining moderation by sex/gender revealed that this association was significant only for females. These results suggest that irritability may play a key role in the persistence and worsening of hyperactive/impulsive symptoms across adolescence for females, with potential implications for the diagnosis and treatment of females with ADHD.

Factors Associated With Accidental Injuries in Children With ADHD-Combined Type: More Than a Motor Problem?

Objective: We explored the relationship between accidental injuries, motor impairment, and co-occurring autism spectrum disorder (ASD) symptoms in children with ADHD-combined type (ADHD-CT). Method: Participants were 32 male children diagnosed with ADHD-CT and 23 typically developing male children (7-12 years, full scale IQ [FSIQ] > 80). Parents completed a customized questionnaire on the occurrence of accidental injuries (e.g., bruises, cuts) their child experienced in the past 12 months. Motor proficiency was assessed using the Movement ABC-2 (MABC-2). Parents rated motor, ADHD-CT, ASD, and anxiety symptoms. Results: Children with ADHD-CT had significantly increased parent-reported accidental injuries compared with typically developing children. Among children with ADHD-CT, Spearman's rho rank correlations revealed no association between increased accidental injuries and MABC-2 score, but significant associations with increased hyperactivity/impulsivity, ASD, and anxiety symptoms. Conclusion: Although these findings require validation, they suggest a need for further research investigating the contribution of co-occurring ASD and anxiety symptoms to accidental injuries in children with ADHD-CT.

Latent Class Analysis of ADHD Neurodevelopmental and Mental Health Comorbidities

OBJECTIVE

Many children diagnosed with attention-deficit/hyperactivity disorder (ADHD) experience co-occurring neurodevelopmental and psychiatric disorders, and those who do often exhibit higher levels of impairment than children with ADHD alone. This study provides a latent class analysis (LCA) approach to categorizing children with ADHD into comorbidity groups, evaluating condition expression and treatment patterns in each group.

METHODS

Parent-reported data from a large probability-based national sample of children diagnosed with ADHD (2014 National Survey of the Diagnosis and Treatment of ADHD and Tourette Syndrome) were used for an LCA to identify groups of children with similar groupings of neurodevelopmental and psychiatric comorbidities among children with current ADHD (n = 2495). Differences between classes were compared using multivariate logistic regressions.

RESULTS

LCA placed children who were indicated to have ADHD into 4 classes: (low comorbidity [LCM] [64.5%], predominantly developmental disorders [PDD] [13.7%], predominantly internalizing disorders [PID] [18.5%], and high comorbidity [HCM] [3.3%]). Children belonging to the HCM class were most likely to have a combined ADHD subtype and the highest number of impaired domains. Children belonging to the PDD class were most likely to be receiving school services, whereas children in the PID class were more likely to be taking medication than those belonging to the LCM class who were least likely to receive psychosocial treatments.

CONCLUSION

Latent classes based on co-occurring psychiatric conditions predicted use of varied treatments. These findings contribute to the characterization of the ADHD phenotype and may help clinicians identify how services could be best organized and coordinated in treating ADHD.

Homogeneous Combinations of ASD-ADHD Traits and Their Cognitive and Behavioral Correlates in a Population-Based Sample

OBJECTIVE

Autism Spectrum Disorders (ASD) and ADHD are assumed to be the extreme manifestations of continuous heterogeneous traits that frequently co-occur. This study aims to identify subgroups of children with distinct ASD-ADHD trait profiles in the general population, using measures sensitive across both trait continua, and show how these subgroups differ in cognitive functioning.

METHOD

We examined 378 children (6-13 years) from a population-based sample.

RESULTS

Latent class analyses (LCA) detected three concordant classes with low (10.1%), medium (54.2%), or high (13.2%) scores on both traits, and two discordant classes with more ADHD than ASD characteristics (ADHD > ASD, 18.3%) and vice versa (ASD > ADHD, 4.2%). Findings suggest that ASD and ADHD traits usually are strongly related in the unaffected population, and that a minority of children displays atypical discordant trait profiles characterized by differential visual-spatial functioning.

CONCLUSION

This dissociation suggests that heterogeneity in ASD and ADHD is rooted in heterogeneity in the lower unaffected end of the distribution.

The clinical presentation of attention deficit-hyperactivity disorder (ADHD) in children with 22q11.2 deletion syndrome

BACKGROUND

Although attention deficit-hyperactivity disorder (ADHD) is the most prevalent psychiatric disorder in children with 22q11.2DS, it remains unclear whether its clinical presentation is similar to that in children with idiopathic ADHD. The aim of this study is to compare the ADHD phenotype in children with and without 22q11.2DS by examining ADHD symptom scores, patterns of psychiatric comorbidity, IQ and gender distribution.

METHODS

Forty-four children with 22q11.2DS and ADHD (mean age = 9.6), 600 clinic children (mean age = 10.8) and 77 children with ADHD from a population cohort (mean age = 10.8) participated in the study. Psychopathology was assessed using parent-report research diagnostic instruments.

RESULTS

There was a higher proportion of females in the 22q11.2DS ADHD sample in relation to the clinical sample (χ(2)  = 18.2, P < 0.001). The 22q11.2DS group showed a higher rate of ADHD inattentive subtype (χ(2)  = 114.76, P < 0.001), and fewer hyperactive-impulsive symptoms compared to the clinical group (z = 8.43, P < 0.001). The 22q11.2DS ADHD group parents reported fewer oppositional defiant disorder/conduct disorder symptoms (z = 6.33, P < 0.001) and a higher rate of generalized anxiety disorder (χ(2)  = 4.56, P = 0.03) in relation to the clinical group. Two percent of the 22q11.2 DS ADHD sample had received ADHD treatment. The results were similar when the 22q11.2 ADHD group was compared to the population cohort ADHD group.

CONCLUSIONS

The clinical presentation of ADHD and patterns of co-morbidity in 22q11.2DS is different from that in idiopathic ADHD. This could lead to clinical under-recognition of ADHD in this group. Examining psychopathology in 22q11.2DS can provide insights into the genetic origins of psychiatric problems with implications beyond the 22q11.2DS population.

Prevalence of oppositional defiant disorder in Spain

INTRODUCTION

Oppositional defiant disorder (ODD) is characterized by a pattern of negative, defiant, disobedient and hostile behavior toward authority figures. ODD is one of the most frequent reasons for clinical consultation on mental health during childhood and adolescence. ODD has a high morbidity and dysfunction, and has important implications for the future if not treated early.

OBJECTIVE

To determine the prevalence of ODD in schoolchildren aged 6-16 years in Castile and Leon (Spain).

MATERIAL AND METHODS

Population study with a stratified multistage sample, and a proportional cluster design. Sample analyzed: 1,049. Cases were defined according to DSM-IV criteria.

RESULTS

An overall prevalence rate of 5.6% was found (95% CI: 4.2%-7%). Male gender prevalence=6.8%; female=4.3%. Prevalence in secondary education=6.2%; primary education=5.3%. No significant differences by gender, age, grade, type of school, or demographic area were found. ODD prevalence without considering functional impairment, such as is performed in some research, would increase the prevalence to 7.4%. ODD cases have significantly worse academic outcomes (overall academic performance, reading, maths and writing), and worse classroom behavior (relationship with peers, respect for rules, organizational skills, academic tasks, and disruption of the class).

CONCLUSIONS

Castile and Leon has a prevalence rate of ODD slightly higher to that observed in international publications. Depending on the distribution by age, morbidity and clinical dysfunctional impact, an early diagnosis and a preventive intervention are required for health planning.

Caregiver survey of pharmacotherapy to treat attention deficit/hyperactivity disorder in individuals with Williams syndrome

Williams syndrome (WS) is a genetic condition characterized by a unique neurocognitive and behavioral profile, including increased incidence of attention deficit/hyperactivity disorder (ADHD). The purpose of the present study was to examine the perceived helpfulness and side effects of medications used to treat ADHD (methylphenidate class, amphetamine class, atomoxetine) in individuals with WS. This was accomplished with a survey of parents/caregivers of individuals with WS through the Williams Syndrome Association. Five-hundred twelve (512) parents/caregivers responded to the survey regarding their child's/adult child's use of ADHD medications. Twenty-seven percent (27%) of the individuals had been prescribed a medication for ADHD, most commonly a methylphenidate class medication. OROS-methylphenidate was reported as the most helpful methylphenidate class formulation, with 74% reporting it at least somewhat helpful. Survey participants reported similar side effects as typically developing controls, but to a greater degree. Irritability was the most commonly endorsed side effect of an ADHD medication (38%). Individuals reported use of stimulant medications in the presence and absence of underlying cardiac conditions, with 56% of ADHD medication users reporting supravalvular aortic stenosis, 36% pulmonary artery stenosis, and 25% systemic hypertension. Individuals taking ADHD medications were more likely to report dental problems (p=0.004). Additional studies are needed to further investigate these findings and examine short-versus long-acting stimulant medications and dosage effects.

Exploration of ADHD Subtype Definitions and Co-Occurring Psychopathology in a Missouri Population-Based Large Sibship Sample

BACKGROUND

There is some debate regarding the utility of Attention-Deficit/ Hyperactivity Disorder (ADHD) subtypes as currently defined. Differences in co-occurring psychopathology among subtypes would support the validity of subtype definitions.

OBJECTIVE

To explore how ADHD subtype relates to co-occurring psychopathology in a large population-based sample of children and adolescents (n=5744).

METHOD

Parents completed the Strengths and Weaknesses of ADHD-symptoms and Normal behavior (SWAN) questionnaire, the Child Behavior Checklist (CBCL) and the Social Responsiveness Scale (SRS). Methods including discriminant analysis, principal components analysis, and fractional polynomial regression were used to examine the relationship between ADHD diagnostic subtypes and co-occurring psychopathology.

RESULTS

Children with different ADHD subtypes show differences on several CBCL subscales. A combination of CBCL subscales and SRS score had good ability to discriminate ADHD subtypes. Conversely, for the same overall number of ADHD symptoms, individuals who present with both inattentive and hyperactive/impulsive symptoms exhibit higher severity of co-occurring psychopathology on a summary measure derived from principal components analysis of the CBCL subscales and SRS. This includes some subjects who fail to meet the DSM-IV-TR ADHD symptom criterion due to having less than 6 inattentive and less than six hyperactive-impulsive symptoms, yet have ADHD symptom severity similar to those with the inattentive or hyperactive-impulsive subtype.

CONCLUSIONS

Several convergent lines of analysis provide support for the continued use of ADHD subtypes (or current presentation symptom profiles), as evidenced by differences in co-existing psychopathlogy. We also found that current diagnostic criteria may fail to identify a potentially impaired group of individuals who have low-to-moderate levels of both inattention and hyperactivity/impulsivity. Under the upcoming DSM-5, it will be important for clinicians to consider the option of giving an ADHD "not elsewhere classified" diagnosis to such children.

Phenotype refinement for comorbid attention deficit hyperactivity disorder and reading disability

Comorbidity between Attention Deficit Hyperactivity Disorder (ADHD) and reading disability (RD) is common; however, the heritability of this comorbidity is not well understood. This may be due to the complexity and heterogeneity of ADHD and RD phenotypes. Using alternative ADHD-RD sub-phenotypes instead of those arising from the DSM-IV may lead to greater success in the search for comorbid ADHD-RD susceptibility genes. Therefore, this study aims to refine ADHD-RD phenotypes into homogenous informative sub-phenotypes using latent class analysis (LCA). LCA was performed on 2,610 Australian twin families (6,535 individuals) in order to generate probabilistic genetically distinct classes that define ADHD-RD subtypes, including comorbidity, based on related symptom clusters. The LCA separated the phenotypes for ADHD and RD into nine classes. One class was unaffected; three classes demonstrated the three DSM-IV subtypes of ADHD, three subtypes showed different severities of RD, and two classes expressed a combination of RD and ADHD subtypes. LCA proved effective in refining the phenotypes of ADHD alone, RD alone, and ADHD-RD comorbidity, and its ability to classify them into homogenous groups based on clusters of symptoms, suggesting that the latent classes may be robust enough to use in molecular genetic studies.

Animal models of ADHD

Studies employing animal models of attention-deficit/hyperactivity disorder (ADHD) present clear inherent advantages over human studies. Animal models are invaluable tools for the study of underlying neurochemical, neuropathological and genetic alterations that cause ADHD, because they allow relatively fast, rigorous hypothesis testing and invasive manipulations as well as selective breeding. Moreover, especially for ADHD, animal models with good predictive validity would allow the assessment of potential new therapeutics. In this chapter, we describe and comment on the most frequently used animal models of ADHD that have been created by genetic, neurochemical and physical alterations in rodents. We then discuss that an emerging and promising direction of the field is the analysis of individual behavioural differences among a normal population of animals. Subjects presenting extreme characteristics related to ADHD can be studied, thereby avoiding some of the problems that are found in other models, such as functional recovery and unnecessary assumptions about aetiology. This approach is justified by the theoretical need to consider human ADHD as the extreme part of a spectrum of characteristics that are distributed normally in the general population, as opposed to the predominant view of ADHD as a separate pathological category.

ADHD across cultures: is there evidence for a bidimensional organization of symptoms?

We examined the phenotypic expression of attention-deficit/hyperactivity disorder (ADHD) across cultures by assessing the factor/latent class structure of its core symptoms. We conducted a systematic review of the literature published from January 1987 to November 2008 using Medline and PsycINFO. We systematically reviewed 2,511 article abstracts, and 48 of these abstracts were included in this review. Research with school-age children from 15 countries including different samples, informants, and rating instruments supported a two-factor ADHD model consisting of inattention and combined hyperactivity and impulsivity. This model was not supported for preschool children. Cross-cultural equivalence for the two-factor model was suggested in some studies. Latent class analyses using parental data and more recent approaches like factor mixture modeling are generally consistent with factor analyses. These findings argue in favor of a cross-cultural validity of the syndrome. The implications of these findings for further research and classificatory systems in mental health like the Diagnostic and Statistical Manual of Mental Disorders (5th ed.) are discussed.

Family-based genome-wide association scan of attention-deficit/hyperactivity disorder

OBJECTIVE

Genes likely play a substantial role in the etiology of attention-deficit/hyperactivity disorder (ADHD). However, the genetic architecture of the disorder is unknown, and prior genome-wide association studies (GWAS) have not identified a genome-wide significant association. We have conducted a third, independent, multisite GWAS of DSM-IV-TR ADHD.

METHOD

Families were ascertained at Massachusetts General Hospital (MGH; N = 309 trios), Washington University at St. Louis (WASH-U; N = 272 trios), and University of California at Los Angeles (UCLA; N = 156 trios). Genotyping was conducted with the Illumina Human1M or Human1M-Duo BeadChip platforms. After applying quality control filters, association with ADHD was tested with 835,136 SNPs in 735 DSM-IV ADHD trios from 732 families.

RESULTS

Our smallest p value (6.7E-07) did not reach the threshold for genome-wide statistical significance (5.0E-08), but one of the 20 most significant associations was located in a candidate gene of interest for ADHD (SLC9A9, rs9810857, p = 6.4E-6). We also conducted gene-based tests of candidate genes identified in the literature and found additional evidence of association with SLC9A9.

CONCLUSIONS

We and our colleagues in the Psychiatric GWAS Consortium are working to pool together GWAS samples to establish the large data sets needed to follow-up on these results and to identify genes for ADHD and other disorders.

ADHD latent class clusters: DSM-IV subtypes and comorbidity

ADHD (Attention Deficit Hyperactivity Disorder) has a complex, heterogeneous phenotype only partially captured by Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria. In this report, latent class analyses (LCA) are used to identify ADHD phenotypes using K-SADS-IVR (Schedule for Affective Disorders & Schizophrenia for School Age Children-IV-Revised) symptoms and symptom severity data from a clinical sample of 500 ADHD subjects, ages 6-18, participating in an ADHD genetic study. Results show that LCA identified six separate ADHD clusters, some corresponding to specific DSM-IV subtypes while others included several subtypes. DSM-IV comorbid anxiety and mood disorders were generally similar across all clusters, and subjects without comorbidity did not aggregate within any one cluster. Age and gender composition also varied. These results support findings from population-based LCA studies. The six clusters provide additional homogenous groups that can be used to define ADHD phenotypes in genetic association studies. The limited age ranges aggregating in the different clusters may prove to be a particular advantage in genetic studies where candidate gene expression may vary during developmental phases. DSM-IV comorbid mood and anxiety disorders also do not appear to increase cluster heterogeneity; however, longitudinal studies that cover period of risk are needed to support this finding.

Attention deficit hyperactivity disorder: a Rasch analysis of the SWAN Rating Scale

The prevalence of attention-deficit/hyperactivity disorder (ADHD) has been estimated at 3-7% in the population. Children with this disorder are often characterized by symptoms of inattention and/or impulsivity and hyperactivity, which can significantly impact on many aspects of their behaviour and performance. This study investigated the characteristics of the SWAN Rating Scale and its discrimination of ADHD subtypes. This instrument was developed by Swanson and his colleagues and measures attentiveness and hyperactivity on a continuum, from attention problems to positive attention skills, using a seven-point scale of behaviour: "far below average" to "far above average". The Australian Twin Attention-Deficit/Hyperactivity Disorder Study consists of questionnaire data collected from families in 1990/2007. The Rasch model was used to measure the characteristics of items from the SWAN Rating Scale; how well these items discriminated between those with and without ADHD. The prevalence of each subtype was found to be 5.3% for inattentive ADHD, 4.3% for hyperactive ADHD and 4.6% for combined ADHD. A total of 14.2% of the cohort appeared to have ADHD. While the inattentive items appeared to be consistent with each other in their measurement behaviour and response patterns, the hyperactive items were less consistent. Further, the combined subtype appeared to be an entirely different type, with unique features unlike the other two subtypes. Further work is needed to distinguish the diagnostic features of each subtype of ADHD.

Maternal ratings of attention problems in ADHD: evidence for the existence of a continuum

OBJECTIVE

To investigate whether items assessing attention problems provide evidence of quantitative differences or categorically distinct subtypes of attention problems (APs) and to investigate the relation of empirically derived latent classes to DSM-IV diagnoses of subtypes of attention-deficit/hyperactivity disorder (ADHD), for example, combined subtype, predominantly inattentive type, and predominantly hyperactive/impulsive type.

METHOD

Data on attention problems were obtained from maternal ratings on the Child Behavior Check List (CBCL). Latent class models, which assume categorically different subtypes, and factor mixture models, which permit severity differences, are fitted to data obtained from Dutch boys at age 7 (N = 8,079), 10 (N = 5,278), and 12 years (N = 3,139). The fit of the different models to the data is compared to decide which model, and hence, which corresponding interpretation of AP, is most appropriate. Next, ADHD diagnoses are regressed on latent class membership in a subsample of children.

RESULTS

At all the three ages, models that distinguish between three mainly quantitatively different classes (e.g., mild, moderate, and severe attention problems) provide the best fit to the data. Within each class, the CBCL items measure three correlated continuous factors that can be interpreted in terms of hyperactivity/impulsivity, inattentiveness/dreaminess, and nervous behavior. The AP severe class contains all of the subjects diagnosed with ADHD-combined subtype. Some subjects diagnosed with ADHD-predominantly inattentive type are in the moderate AP class.

CONCLUSIONS

Factor mixture analyses provide evidence that the CBCL AP syndrome varies along a severity continuum of mild to moderate to severe attention problems. Children affected with ADHD are at the extreme of the continuum. These data are important for clinicians, research scholars, and the framers of the DSM-V as they provide evidence that ADHD diagnoses exist on a continuum rather than as discrete categories.

Developmental psychopathology: Attention Deficit Hyperactivity Disorder (ADHD)

BACKGROUND

Attention Deficit/Hyperactivity Disorder (ADHD), formerly regarded as a typical childhood disorder, is now known as a developmental disorder persisting over the lifespan. Starting in preschool-age, symptoms vary depending on the age group affected.

METHOD

According to the variability of ADHD-symptoms and the heterogeneity of comorbid psychiatric disorders, a broad review of recent studies was performed. These findings were summarized in a developmental psychopathological model, documenting relevant facts on a timeline.

RESULTS

Based on a genetic disposition and a neuropsychological deregulation, there is evidence for factors which persist across the lifespan, change age-dependently, or show validity in a specific developmental phase. Qualitative changes can be found for children in preschool-age and adults.

CONCLUSION

These differences have implications for clinical practice as they can be used for prevention, diagnostic proceedings, and therapeutic intervention as well as for planning future studies. The present article is a translated and modified version of the German article "Entwicklungspsychopathologie der ADHS", published in Zeitschrift für Psychiatrie, Psychologie und Psychotherapie, 56, 2008, S. 265-274.

Simple identification of complex ADHD subtypes using current symptom counts

OBJECTIVE

New attention-deficit/hyperactivity disorder (ADHD) subtypes identified through latent class analysis have been recently proposed. Here, we assess the accuracy of simple rules based on symptom counts for the assignment of youths to clinically relevant population-derived ADHD subtypes: severe inattentive (SI) and severe combined (SC).

METHOD

Data from 9,675 twins and siblings from Missouri and Australia aged 7 to 19 years were analyzed using continuous and categorical models of ADHD symptoms using principal components analysis and subtyping by DSM-IV and by latent class criteria. Cut points were derived for classifying SI and SC subtypes by positive predictive value, negative predictive value, percent positive agreement, and Matthew coefficient of agreement.

RESULTS

Principal components analysis suggested two underlying factors: total number of symptoms and symptom type, with SI and SC latent class subtypes clearly mapping to distinct areas on a plot of these factors. Having six or more total symptoms and fewer than three hyperactive-impulsive symptoms accurately predicts the latent class SI subtype. The latent class SC subtype was best identified by 11 or more total symptoms and 4 or more hyperactive-impulsive. The DSM-IV ADHD subtype criteria accurately identified the SC subtype but only poorly for the SI subtype.

CONCLUSIONS

Symptom counts criteria allow the simple and accurate identification of subjects with severe ADHD subtypes defined by latent class analysis. Such simple symptom counts corresponding to screening cut points selected latent class-derived SI subtype subjects with greater precision than DSM-IV criteria.

Diversidade de resultados no estudo do transtorno de déficit de atenção e hiperatividade

Com este artigo pretende-se abordar a problemática da diversidade de dados na investigação do Transtorno de Déficit de Atenção e Hiperatividade (TDAH). Apresenta-se uma revisão da literatura centrada na heterogeneidade de conclusões relativas à caracterização do transtorno, à distinção dos subtipos, aos contextos de informação, às diferenças de gênero e à comorbidade. Na tentativa de compreender a disparidade de conclusões, salientam-se potenciais fatores explicativos, nomeadamente a heterogeneidade das amostras, a diversidade de metodologias e de procedimentos de investigação, entre outros. A revisão efetuada baseou-se, majoritariamente, em publicações referenciadas pelas bases de dados PsycInfo e ERIC, e, pontualmente, PubMed e Elsevier Direct.

Patterns of psychopathology in children with ADHD: a latent profile analysis

This study used latent profile modeling (LPA) with a community sample that included an enriched sampling of children (aged 6-11) diagnosed with attention deficit/hyperactivity disorder (ADHD) (N = 271). Six classes of ADHD emerged from our LPA; only 17% of children fell into a class without significant co-occurring symptoms. In addition, nearly half of children were assigned to classes that could not be reliably distinguished using existing DSM-IV subtypes. For the most part, each of the classes was clearly differentiated from a sample of community controls and had clinical diagnoses and child self-reports that were consistent with expectations given by their latent profile of symptoms. Although each of the respective classes of ADHD had elevated levels of hyperactivity and/or attention problems, the current findings suggest that an exclusive reliance on these dimensions is a largely inadequate method of subtype classification. To the contrary, our findings suggest that ADHD subtypes can be more reliably partitioned based on the degree to which they display disruptive behavior, internalizing symptoms, or both.

Aufmerksamkeitstherapie bei Kindern - Langzeiteffekte des ATTENTIONERS

Zusammenfassung: Fragestellung: Viele Kinder leiden an Aufmerksamkeitsstörungen; bei einem wesentlichen Anteil ist das Kardinalsymptom Unaufmerksamkeit und hier insbesondere das Aufmerksamkeitssteuerungsdefizit vorherrschend. Mit dem ATTENTIONER liegt ein effektives Therapieprogramm zur Behandlung solcher Steuerungsdefizite vor. Methodik: Bereits 2007 berichteten Jacobs und Petermann über erste Langzeiteffekte in einer Nachuntersuchung durchschnittlich zehn Wochen nach Therapieende. In der vorliegenden Studie erfolgten drei Verlaufsmessungen: Vor Beginn der Intervention, direkt nach der Intervention sowie eine Follow-up-Untersuchung zehn bis 76 Monate nach der ersten Nachtestung. Ergebnisse: Es zeigen sich bedeutsame Langzeiteffekte bei der Überprüfung der Aufmerksamkeitssteuerung. Die überwiegende Anzahl der Patienten erzielt auch in der Follow-up-Untersuchung Ergebnisse im Durchschnittsbereich, also außerhalb des klinisch relevanten Bereichs. Schlussfolgerungen: Mit dem Attentioner lassen sich also bei den meisten Kindern stabile Therapieeffekte erzielen.

Somatosensory functioning and experienced pain in ADHD-families: a pilot study

BACKGROUND

An issue somewhat overlooked in children with Attention Deficit/Hyperactivity Disorder (ADHD) is somatosensory functioning. Some studies show a deficit in the processing of tactile and kinesthetic stimuli, but more research is needed to confirm these findings. A related topic, namely the subjective experience of pain, has not been investigated. Also unknown is the somatosensory functioning and experienced pain of non-affected siblings of children with ADHD, which may shed light on the familiality of possible alterations in somatosensory functioning and experienced pain. Therefore, the present study aimed to investigate these aspects in children with ADHD and their non-affected siblings, and to investigate how these aspects were related to each other.

METHOD

Somatosensory functioning (tactile perception and kinesthesia) and subjective intensity and emotionality of pain experiences were examined in 50 children with ADHD, their 38 non-affected siblings and 35 normal controls.

RESULTS

Both children with ADHD and their non-affected siblings showed deficits in tactile perception, though kinesthesia appeared unimpaired. Non-affected siblings reported a significant lower intensity and emotionality of past experienced pain than controls. The 'objective' tests of somatosensory functioning did not relate to the subjective sensation of pain.

CONCLUSIONS

Alterations in tactile perception may relate to a familial susceptibility for ADHD. Clinicians should be aware of possible under reportage of experienced pain in siblings of children with ADHD. The intensity and emotionality of pain appears difficult to objectify with somatosensory test.

Gender and age differences in medications dispensed from a national chain drugstore

OBJECTIVES

Our objective was to compare sex and age differences in the medications dispensed in pharmacies from a large national drugstore chain.

METHODS

Using a list for the 200 most commonly prescribed medicines, we assessed prescriptions dispensed by a large national chain drug store over 1 year (2002-2003). The analysis used U.S. census data adjusted for the population by sex and age and weighted by the number of pharmacies per state. Results are reported as an odds ratio (OR) of prescriptions dispensed to females and males.

RESULTS

Under age 18, 24 drug classes were dispensed more commonly to females (OR > 1) and 18 drug classes more commonly to males (OR < 1). In the 18-24 age group, 48 of 53 drug classes were dispensed more frequently to females. Across other adult groups, females were dispensed more medications than males for 156 of 180 medications. There was greater dispensing to females of antibiotics (OR = 1.74, 95% confidence interval [CI] 1.74-1.74), analgesics (OR = 1.70, 95% CI 1.70-1.70), antihistamines and sympathomimetics (OR = 1.46, 95% CI 1.45-1.46), benzodiazapines (OR = 2.08, 95% CI 2.07-2.08), antidepressants (OR = 2.40, 95% CI 2.39-2.40), diuretics (OR = 1.9328, 95% CI 1.93-1.94), and thyroid drugs (OR = 4.80, 95% CI 4.78-4.82). However, males had higher dispensing of antianginal drugs (OR = 0.84, 95% CI 0.83-0.85), anticoagulants (OR = 0.89, 95% CI 0.88-0.90), glycosides (OR = 0.80, 95% CI 0.79-0.81), and antihypertensives (OR = 0.91, 95% CI 0.91-0.91). More females were dispensed propoxyphene with acetaminophen (OR = 2.23, 95% CI 2.23-2.24), which has been associated with adverse outcomes (hospitalizations, emergency department visits, and deaths).

CONCLUSIONS

Females, especially during the reproductive years, are dispensed more medications than males.

Poor utility of the age of onset criterion for DSM-IV attention deficit/hyperactivity disorder: recommendations for DSM-V and ICD-11

BACKGROUND

To test whether the retrospective reporting of the age of onset impairment criterion for attention deficit/hyperactivity disorder (ADHD) required in the Diagnostic and Statistical Manual of Mental Disorders - IV (DSM-IV) complicates identification of new and known child and adolescent cases later in life.

METHODS

A birth-records-based cohort of twins assessed at ages 7 to 19 years were blindly reassessed five years later using the MAGIC interview. Study outcome measures were differences in reported ages of onset for attention deficit/hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), conduct disorder (CD) and major depressive disorder (MDD).

RESULTS

For all age groups and respondents (parent on youth or youth self-report), later ages of ADHD onset were reported five years later. The same phenomenon was also present for the other diagnostic groups. Of the initial ADHD individuals who continued to meet all other ADHD criteria at follow-up, 46% failed the age of onset criterion five years later. When ignoring the age of onset criterion, late onsets of ages 7-16 years accounted for about 10% of all ADHD.

CONCLUSIONS

Use of the DSM-IV age of onset criterion for attention deficit/hyperactivity disorder in the assessment of adolescents and young adults results in under-identification of affected individuals. Consideration should be given to revising the current nomenclatures to reflect the reality of retrospective reporting errors in age of onset as well as the presence of late onset cases.

Association of dopamine, serotonin, and nicotinic gene polymorphisms with methylphenidate response in ADHD

Gene polymorphisms of the 3' untranslated region (3'-UTR) of the dopamine transporter (DAT1), Dopamine receptor exon 3 D4 variable number tandem repeat (DRD4VNTR), nicotinic acetylcholine receptor alpha 4 subunit (CHRNA4) and serotonin transporter promoter (SLC6A4-5HTTLPR) are under consideration as potential risk factors for attention-deficit/hyperactivity disorder (ADHD). A post-hoc attempt was made to investigate the association between the allelic variations of these candidate genes and retrospective parental report of response to methylphenidate in an ADHD-enriched, population-based twin sample. Subjects (N = 243) were selected from the twin sample based on parent report that the child had been treated with methylphenidate for ADHD symptoms. The functional polymorphisms screened were the VNTR located in the 3'-UTR of the dopamine transporter, DRD4 VNTR, CHRNA4 (rs1044396 and rs6090384) and the long (L(A) and L(G)) and short (S) forms of the serotonin transporter promoter region. Logistic regression did not demonstrate a significant association between methylphenidate treatment response and the relevant polymorphisms. The sample size had high power to detect effect sizes similar to those reported in some prior methylphenidate pharmacogenetic studies; however, the categorical (yes/no) measure of parent-reported treatment response may not have been sensitive enough to pick up statistically significant differences in treatment response based on genotype. Further studies including quantitative measures of treatment response are warranted.

Co-occurrence of motor problems and autistic symptoms in attention-deficit/hyperactivity disorder

OBJECTIVE

To investigate the relation between parent reports of motor problems and clinically significant autistic symptoms in children with and without attention-deficit/hyperactivity disorder (ADHD).

METHOD

Subjects were male (n = 521) and female (n = 330) twins from an epidemiological study of ADHD, ages 7 to 19 years at assessment using the Child Behavior Checklist and semistructured psychiatric diagnostic interviews. Parent-rated Social Responsiveness Scale questionnaires were returned for 62% of 1,647 individuals who participated in interviews. After exclusion of subjects with incomplete data or evidence of mental retardation, 851 subjects (52%) were available for the present study analysis. Each subject was classified by DSM-IV ADHD subtype and assigned to one of seven population-defined ADHD subtypes based on latent class analysis of DSM-IV ADHD symptoms. Within each ADHD subtype, we examined the relation between Child Behavior Checklist motor problem endorsement and elevated autistic symptoms on the Social Responsiveness Scale.

RESULTS

Motor problems and high levels of autistic traits were most common in individuals with combined-type ADHD. Within each of the clinically relevant DSM-IV and latent class ADHD subtypes, individuals with the combination of motor problems and ADHD were more likely to have high levels of autistic traits than those with ADHD alone.

CONCLUSIONS

Children with the combination of ADHD and parent-reported motor coordination deficits have elevated levels of autistic symptoms. Targeted treatment and prevention interventions may be warranted. The exclusion criteria for DSM-IV ADHD should be revised to reflect these population-based findings.

Epidemiologic considerations in attention deficit hyperactivity disorder: a review and update

Epidemiologic data on attention deficit hyperactivity disorder (ADHD) are essential for planning health services and implementing strategies of detection and early intervention, with possible substantial benefits on public health. This article addresses methodological aspects of prevalence studies, recent findings on the prevalence of ADHD in childhood and adolescence based on a systematic review, current findings on the persistence of the disorder over time and prevalence in adulthood, and factors associated with ADHD. Evidence from the reviewed literature indicates the importance of methodological aspects in the understanding of epidemiologic findings and the necessity of large-scale cross-national studies. Moreover, governments clearly must direct attention to childhood mental disorders to guarantee a healthy future for their countries.

Predictors of stability of attention-deficit/hyperactivity disorder subtypes from childhood to young adulthood

OBJECTIVE

To determine the 5-year prospective stability of population-based and DSM-IV subtypes of attention-deficit/hyperactivity disorder (ADHD) as well as to explore predictors of stability.

METHOD

A total of 708 twins ages 7 to 19 years who were identified from birth records of the state of Missouri and had participated in a study of ADHD were reassessed 5 years later in a blinded fashion. Stabilities of DSM-IV and population-based ADHD subtypes were compared using percentage of agreement with significance tested by the kappa statistic. Predictors of stability of subtype diagnosis were determined using multivariate logistic regression.

RESULTS

In general, 5-year ADHD subtype stability was poor to modest and ranged from 11.1% to 24.0% for DSM-IV for subtypes and from 14.3% to 35.3% for clinically significant population-derived subtypes. There were no predictors of diagnostic stability that applied across subtypes. There were subtype-specific predictors including a diagnosis of oppositional defiant disorder for DSM-IV primarily inattentive ADHD; lower verbal IQ for DSM-IV combined type ADHD; and younger age, oppositional defiant disorder, and medication use for population-defined severe combined ADHD.

CONCLUSIONS

Population-defined ADHD subtype criteria demonstrated modestly improved diagnostic stability over 5 years compared to DSM-IV subtypes. Few correlates or predictors of stability were identified.

Gene-environment interactions in the development of combined type ADHD: evidence for a synapse-based model

To determine the mechanism of interaction of prenatal smoking exposure and child genotype in the development of attention deficit/hyperactivity disorder (ADHD), polymorphisms in the CHRNA4 gene were tested for interactions with prenatal smoking exposure on risk for ADHD subtypes using multiple logistic regression. An exon 5 polymorphism demonstrated a significant interaction with history of maternal smoking during pregnancy for increasing risk for severe combined type ADHD (OR = 3.0, 95% CI 1.1-8.4 for population-defined severe combined type, OR = 3.9 95% CI 1.2-13.1 for DSM-IV defined combined subtype ADHD). This interaction increased the effects of previously reported interactions for the DRD4 and DAT1 genes with prenatal smoking exposure. Given the known functions and the known areas of expression of these three genes at the dopaminergic synapse in the pre-frontal cortex, the results are compatible with a synapse-based model of the development of this form of ADHD. The subtype specificity of these findings supports the concept that ADHD is composed of a group of distinct disorders.

Comorbidity of internalizing disorders in children with oppositional defiant disorder

Oppositional defiant disorder (ODD) is often comorbid with other psychiatric disorders in childhood. Its association with attention deficit hyperactivity disorder and conduct disorder has been well studied. Recent studies suggest that children with ODD have substantial comorbidity with anxiety and depressive (internalizing) disorders, as well. Identifying the pattern of internalizing comorbidity with ODD in childhood and adolescence and how this varies across age and gender may help to identify mechanisms of such comorbidity. This systematic review presents evidence on the association of internalizing disorders with ODD across childhood and adolescence. Data from cross-sectional and longitudinal studies in clinic, community and epidemiologic samples are considered separately. Findings suggest that while internalizing comorbidity with ODD is present at all ages, the degree of comorbidity may vary over time in particular groups of children. Girls and boys appear to have different patterns of ODD comorbidity with either anxiety or depression, as well as ages of onset of ODD, however more large studies are required. Children with ODD in early life require further study as they may be a subgroup at increased risk for anxiety and affective disorders. This could have important implications for the treatment of these ODD children and the prevention of sequential comorbidity.

Does the Child Behavior Checklist juvenile bipolar disorder phenotype identify bipolar disorder?

BACKGROUND

A profile of Child Behavior Checklist(CBCL) T-scores>or=70 on the attention problems, aggression, and anxious/depressed subscales has been proposed to identify juvenile bipolar disorder(JBD). We tested this hypothesis in a population-based sample.

METHODS

Data for this analysis come from a birth-records-based twin sample having semi-structured interview and CBCL data (N=1,346). We compared prevalence of DSM-IV psychiatric disorders and suicidal behaviors in CBCL-JBD and non-CBCL-JBD subjects. Twin modeling assessed genetic and environmental contributions to CBCL-JBD. Associations with DRD4 and DAT1 were examined using chi-square tests.

RESULTS

The prevalence of CBCL-JBD was 2.5%. No subjects with CBCL-JBD met criteria for bipolar or other mood disorders. CBCL-JBD subjects had more oppositional defiant disorder (ODD), conduct disorder(CD), and attention deficit hyperactivity disorder(ADHD). The CBCL-JBD profile was uncommon in these disorders. CBCL-JBD subjects more frequently endorsed suicidal behaviors. The CBCL-JBD profile was heritable and associated with the number of DAT1 9-repeat 3' untranslated region alleles.

CONCLUSIONS

The CBCL-JBD phenotype does not correspond with a semi-structured interview assessment of JBD. ADHD, CD, and ODD are common in children with CBCL-JBD but do not account for the profile. Increased suicidal behaviors indicate substantial impairment in CBCL-JBD subjects.

Prenatal smoking exposure and dopaminergic genotypes interact to cause a severe ADHD subtype

BACKGROUND

In utero exposure to smoking and alcohol are common risk factors that have been associated with attention-deficit/hyperactivity disorder (ADHD) in human beings and animal models. Furthermore, molecular studies have focused on the association between ADHD and DNA polymorphisms in dopamine pathway-related genes. We examined the joint effects of genetic and prenatal substance exposures on DSM-IV and population-defined subtypes of ADHD.

METHODS

Logistic regression was used to assess the relationship between ADHD subtypes, DAT1 and DRD4 polymorphisms, and prenatal substance exposures in a birth-record sample of male and female twin pairs, aged 7-19 years.

RESULTS

Interactions between prenatal exposure to smoking and variations in the DAT1 and DRD4 loci were observed in children with either the DSM-IV or population-defined ADHD combined subtypes. The odds of a diagnosis of DSM-IV combined subtype was 2.9 times greater in twins who had inherited the DAT1 440 allele and who were exposed, than in unexposed twins without the risk allele. The OR was 2.6 in the population-defined subtype. Odds ratios for the DRD4 seven-repeat allele were 3.0 (2.8) in the population-defined (DSM-IV) combined ADHD subtypes. The OR for exposed children with both alleles was 9.0 (95% confidence interval=2.0-41.5) for the population-defined combined subtypes.

CONCLUSIONS

Results indicate that smoking during pregnancy is associated with specific subtypes of ADHD in genetically susceptible children.

Tuning major gene variants conditioning human behavior: the anachronism of ADHD

New findings suggest that attention deficit and hyperactivity disorder (ADHD) is the most common behavioral variant associated with a mental condition. ADHD prevalence reaches figures of 18% in populations worldwide. Furthermore, genetic variants conferring susceptibility to develop ADHD are not rare but very frequent and eventually totally fixed in some populations. These patterns of evolution can be associated with the fact that this behavioral trait had provided selective advantage. However, this behavioral trait is now under scrutiny because of new emerging social necessities. Recent molecular and clinical evidence supports Thom Hartmann's Hunter-Farmer theory, reaffirming that ADHD might be an anachronic behavioral trait.

Genetische Befunde bei der Aufmerksamkeitsdefizit- und Hyperaktivitätsstörung (ADHS)

Zusammenfassung: Die Aufmerksamkeitsdefizit- und Hyperaktivitätsstörung (ADHS) ist mit einer Prävalenz von 3-7% eine häufige kinder- und jugendpsychiatrische Störung. Auf der Basis formalgenetischer Studien ergibt sich eine Heritabilitätsschätzung von 60-80% für ADHS mit einem ca. 5-fach erhöhten Risiko für erstgradige Verwandte von Betroffenen. Bislang vier Genomscans lieferten potentiell relevante chromosomale Regionen, insbesondere den einheitlichen Kopplungsbefund auf 5p13. Aus einer Vielzahl von Assoziationsstudien zu Kandidatengenen deuten aktuelle Metaanalysen auf die Relevanz der Gene der dopaminergen Rezeptoren DRD4 und DRD5 sowie des serotonergen Rezeptors HTR1B und des Synaptosomal Assoziierten Proteins (SNAP-25). In Tiermodellen liegen vorwiegend Paradigmen für Hyperaktivität vor; diese sind in knockout- und Quantitative Trait Loci (QTL) Designs mit viel versprechenden Ergebnissen zum dopaminergen System untersucht worden. Es ist davon auszugehen, dass erst das Zusammenwirken verschiedener Gen-Varianten mit jeweils moderatem bis hin zu kleinem Effekt den Phänotyp ADHS bedingen (Oligo-/ Polygenie) und bei verschiedenen Betroffenen unterschiedliche Kombinationen von prädisponierenden Gen-Polymorphismen zu ADHS führen können. Entsprechend sind für molekulargenetische Studien große Fallzahlen notwendig und die bisherigen Befunde als vorläufig zu interpretieren. Zukunftsweisend für die molekulargenetische Aufklärung von ADHS sind SNP-basierte Genomscans, mit denen 10 000-1 000 000 einzelne Polymorphismen (SNPs) gleichzeitig untersucht werden können. Tiermodelle liefern Hinweise auf die Funktion relevanter Kandidatengene und tragen zur Erweiterung der bislang teilweise widersprüchlichen Kenntnisse zur Neurobiologie des ADHS bei.

ADHD in college students

OBJECTIVE

According to the American Psychiatric Association, 3% to 7% of the school-age population has ADHD and many children continue to display significant symptoms throughout adolescences and adulthood. Relative to the childhood literature, less is known about ADHD in adults, especially college students with ADHD. The principle purpose of this review articles is to summarize the major research findings concerning ADHD in the college student population with regard to prevalence of symptoms, neuropsychological and psychological functioning. Overall, findings suggest that college students with ADHD are at greater risk for academic and psychological difficulties, and they perform similar to non-ADHD controls on many neuropsychological tasks. These findings are preliminary, however, and are tempered by the small number of studies that have been conducted as well as the methodological limitations of these studies.

CONCLUSION

Future research using larger sample sizes, rigorous assessment criteria, and a longitudinal design is needed to better understand the psychological, academic, and neuropsychological functioning of college students with ADHD. Studies are also needed to elucidate the effects of pharmacological and nonpharmacological effects of treatment on the functioning of college students with this disorder.

ADHD medication use in a population-based sample of twins

OBJECTIVE

To determine treatment patterns for youth attention-deficit/hyperactivity disorder (ADHD) symptoms in a general population sample of 1,610 twins.

METHOD

Twin pairs ages 7 to 17 years and parents ascertained from birth records in the state of Missouri were interviewed using the Missouri Assessment of Genetics Interview for Children between 1996 and 2001. Multivariate logistic regression analyses were used to determine which factors were significant in answering three questions about treatment for ADHD.

RESULTS

Of 302 boys, 177 (58.6%) and 26 of 57 girls (45.6%) who met full DSM-IV criteria for ADHD received stimulant medication in this sample. Of 314 youths, 111 (35.4%) who received stimulant medication did not meet DSM-IV criteria for ADHD. When controlling for comorbidity and other factors, the number of impairing ADHD symptoms and having a cotwin who was also brought to treatment for ADHD correlated with referral or treatment in youths without ADHD. Youths without ADHD who were treated had a large number of ADHD symptoms.

CONCLUSION

As is shown in earlier studies, children with ADHD are being undertreated. Complex factors, including comorbid disorders and family history of ADHD treatment, affect treatment patterns in the general population.

Individual differences in the functional neuroanatomy of inhibitory control

We combined the data of five event-related fMRI studies of response inhibition. The re-analysis (n = 71) revealed response inhibition to be accomplished by a largely right hemisphere network of prefrontal, parietal, subcortical and midline regions, with converging evidence pointing to the particular importance of the right frontal operculum. Functional differences were observed between the sexes with greater activity in females in many of these cortical regions. Despite the relatively narrow age range (18-46), cortical activity, on the whole, tended to increase with age, echoing a pattern of functional recruitment often observed in the elderly. More absent minded subjects showed greater activity in fronto-parietal areas, while speed of Go trial responses produced a varied pattern of activation differences in more posterior and subcortical areas. Although response inhibition produces robust activation in a discrete network of brain regions, these results reveal that individual differences impact on the relative contribution made by the nodes of this network.

Validation of population-based ADHD subtypes and identification of three clinically impaired subtypes

Statistically based classification methods have successfully refined ADHD into homogenous and heritable subtypes. External validity and impairment of these subtypes was examined using the Child Behavior Checklist (CBCL). We compared mean CBCL syndrome and competency t-scores across ADHD subtypes defined by latent class analysis in a sample of 1,346 individual twins from Missouri. The potential for comorbidity with conduct disorder (CD), oppositional defiant disorder (ODD), or major depression (MD) to increase impairment in specific ADHD subtypes was also examined. CBCL profiles confirm differences in severity, with more severe classes having increased syndrome scale and decreased competency scale CBCL scores. Clinically significant impairment was found for severe inattentive and combined subtypes and the mild combined subtype. Overall, the presence of comorbid CD, ODD, or MD did not result in increased ADHD subtype impairment. CBCL scores distinguish impairment in ADHD subtypes created through LCA. Comorbidity with CD, ODD, or MD does not significantly increase impairment among ADHD subtypes. The mild combined ADHD subtype represents a clinically significant but under-studied form of ADHD.

Neurogenetic interactions and aberrant behavioral co-morbidity of attention deficit hyperactivity disorder (ADHD): dispelling myths

Background

Attention Deficit Hyperactivity Disorder, commonly referred to as ADHD, is a common, complex, predominately genetic but highly treatable disorder, which in its more severe form has such a profound effect on brain function that every aspect of the life of an affected individual may be permanently compromised. Despite the broad base of scientific investigation over the past 50 years supporting this statement, there are still many misconceptions about ADHD. These include believing the disorder does not exist, that all children have symptoms of ADHD, that if it does exist it is grossly over-diagnosed and over-treated, and that the treatment is dangerous and leads to a propensity to drug addiction. Since most misconceptions contain elements of truth, where does the reality lie?

Results

We have reviewed the literature to evaluate some of the claims and counter-claims. The evidence suggests that ADHD is primarily a polygenic disorder involving at least 50 genes, including those encoding enzymes of neurotransmitter metabolism, neurotransmitter transporters and receptors. Because of its polygenic nature, ADHD is often accompanied by other behavioral abnormalities. It is present in adults as well as children, but in itself it does not necessarily impair function in adult life; associated disorders, however, may do so. A range of treatment options is reviewed and the mechanisms responsible for the efficacy of standard drug treatments are considered.

Conclusion

The genes so far implicated in ADHD account for only part of the total picture. Identification of the remaining genes and characterization of their interactions is likely to establish ADHD firmly as a biological disorder and to lead to better methods of diagnosis and treatment.