The Latent Class Structure of ADHD Is Stable Across Informants

Stimulant medications in children with ADHD normalize the structure of brain regions associated with attention and reward

Children with ADHD show abnormal brain function and structure. Neuroimaging studies found that stimulant medications may improve brain structural abnormalities in children with ADHD. However, prior studies on this topic were conducted with relatively small sample sizes and wide age ranges and showed inconsistent results. In this cross-sectional study, we employed latent class analysis and linear mixed-effects models to estimate the impact of stimulant medications using demographic, clinical measures, and brain structure in a large and diverse sample of children aged 9-11 from the Adolescent Brain and Cognitive Development Study. We studied 273 children with low ADHD symptoms and received stimulant medication (Stim Low-ADHD), 1002 children with high ADHD symptoms and received no medications (No-Med ADHD), and 5378 typically developing controls (TDC). After controlling for the covariates, compared to Stim Low-ADHD and TDC, No-Med ADHD showed lower cortical thickness in the right insula (INS, d = 0.340, PFDR = 0.003) and subcortical volume in the left nucleus accumbens (NAc, d = 0.371, PFDR = 0.003), indicating that high ADHD symptoms were associated with structural abnormalities in these brain regions. In addition, there was no difference in brain structural measures between Stim Low-ADHD and TDC children, suggesting that the stimulant effects improved both ADHD symptoms and ADHD-associated brain structural abnormalities. These findings together suggested that children with ADHD appear to have structural abnormalities in brain regions associated with saliency and reward processing, and treatment with stimulant medications not only improve the ADHD symptoms but also normalized these brain structural abnormalities.

Attachment and comorbid anxiety in ADHD

Anxiety comorbidity is quite common in children with attention-deficit hyperactivity disorder (ADHD). What is known about the relationship between anxiety, attachment and emotion regulation in such children is still limited. We aimed to investigate the associations between attachment, emotion regulation and comorbid anxiety in children with ADHD. 100 children with ADHD and 100 children without any diagnosis aged 8-13 years were included. After the participants were clinically evaluated, Turgay ADHD Scale, Emotion Regulation Checklist, Revised Child Anxiety and Depression Scale-Child Version (RCADS-CV) and Kerns' Security Scale were completed. According to the RCADS-CV scores, ADHD/ANX(+), ADHD/ANX(-), and control groups were formed. The emotional lability/negativity levels were higher in the ADHD groups compared to the non-ADHD controls. Paternal and maternal attachment security levels were lower in the ADHD/ANX(+) group compared to the controls. The regression analysis indicated that higher hyperactivity/impulsivity symptom levels and lower maternal attachment quality were associated with higher anxiety in children with ADHD. These results suggest that focusing on attachment quality and emotion regulation problems may be significant in management of core symptoms and comorbid anxiety problems in children with ADHD.

Latent Class Analysis of Mental Health in Middle Childhood: Evidence for the Dual-Factor Model

Mental health is complex, comprising both mental distress and well-being. This study used latent class analysis to identify common combinations of mental distress and well-being (‘mental health classes’) among schoolchildren aged 8–9 years (N = 3340). Thirteen items, measuring a range of conduct problems, emotional symptoms, and subjective well-being, were included in the analysis. Four mental health classes were identified: (1) complete mental health (n = 1895, 57%), (2) vulnerable (n = 434, 13%), (3) emotional symptoms but content (n = 606, 18%), and (4) conduct problems but content (n = 404, 12%). The classes were reliably identified across different datasets, and for males and females. Differential relations with covariates indicated that mental health classes were distinct and externally valid. The results supported the dual-factor model of mental health, suggesting that mental distress and subjective well-being are separate continua. Three of the four possible combinations of high and low distress and subjective well-being posited by the dual-factor model were found using this inductive statistical method. Importantly, our analysis also revealed two ‘symptomatic but content’ groups, differentiated by symptom domain (internalising/externalising). The covariate analyses between mental health classes and sociodemographic factors, prior academic attainment, school connectedness, and peer support, indicated that there are nuanced relations between those variables and particular constellations of mental distress and well-being. As one of the few dual-factor studies to focus on middle childhood, the current study adds important new evidence that contributes to our understanding of the complexities of mental health among schoolchildren.

The Application of Latent Class Analysis for Investigating Population Child Mental Health: A Systematic Review

Background: Latent class analysis (LCA) can be used to identify subgroups of children with similar patterns of mental health symptoms and/or strengths. The method is becoming more commonly used in child mental health research, but there are reservations about the replicability, reliability, and validity of findings. Objective: A systematic literature review was conducted to investigate the extent to which LCA has been used to study population mental health in children, and whether replicable, reliable and valid findings have been demonstrated. Methods: Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. A search of literature, published between January 1998 and December 2017, was carried out using MEDLINE, EMBASE, PsycInfo, Scopus, ERIC, ASSIA, and Google Scholar. A total of 2,748 studies were initially identified, of which 23 were eligible for review. The review examined the methods which studies had used to choose the number of mental health classes, the classes that they found, and whether there was evidence for the validity and reliability of the classes. Results: Reviewed studies used LCA to investigate both disparate mental health symptoms, and those associated with specific disorders. The corpus of studies using similar indicators was small. Differences in the criteria used to select the final LCA model were found between studies. All studies found meaningful or useful subgroups, but there were differences in the extent to which the validity and reliability of classes were explicitly demonstrated. Conclusions : LCA is a useful tool for studying and classifying child mental health at the population level. Recommendations are made to improve the application and reporting of LCA and to increase confidence in findings in the future, including use of a range of indices and criteria when enumerating classes, clear reporting of methods for replicability, and making efforts to establish the validity and reliability of identified classes.

Theory of mind and emotion regulation difficulties in children with ADHD

Social cognition deficits and emotion dysregulation (ED) are frequently separately studied in relation to ADHD. This study aimed to examine the link between theory of mind (ToM) abilities and ED in children with ADHD. Participants were 200 children aged 11-17 years (study group, n = 100; healthy controls, n = 100). Emotion regulation skills were quantified by using the Difficulties in Emotion Regulation Scale (DERS). ToM was quantified by three different tasks. Diagnostic and Statistical Manual of Mental Disorders, 4th edition, text revision (DSM-IV-TR) Disruptive Behavior Disorders Rating Scale - parents form was used for determination of ADHD symptom severity (ADHD-SS). Children in the study group had more overall difficulties regulating their emotions than healthy controls. Within the study group, a significant correlation was found between the scores of DERS-total and ADHD-SS; and between the scores of DERS-total and gender. The linear regression showed that the predictor variables accounted for 56% of the variation in DERS-total. Unexpected Outcomes Test (UOT) scores significantly improved the accountability of the total variance when added to the linear regression. Our findings show that theory of mind deficits may partly explain ED in children with ADHD.

Game-based combined cognitive and neurofeedback training using Focus Pocus reduces symptom severity in children with diagnosed AD/HD and subclinical AD/HD

Previous studies report reductions in symptom severity after combined working memory (WM) and inhibitory control (IC) training in children with AD/HD. Based on theoretical accounts of the role of arousal/attention modulation problems in AD/HD, the current study examined the efficacy of combined WM, IC, and neurofeedback training in children with AD/HD and subclinical AD/HD. Using a randomized waitlist control design, 85 children were randomly allocated to a training or waitlist condition and completed pre- and post-training assessments of overt behavior, trained and untrained cognitive task performance, and resting and task-related EEG activity. The training group completed twenty-five sessions of training using Focus Pocus software at home over a 7 to 8-week period. Trainees improved at the trained tasks, while enjoyment and engagement declined across sessions. After training, AD/HD symptom severity was reduced in the AD/HD and subclinical groups according to parents, and in the former group only according to blinded teachers and significant-others. There were minor improvements in two of six near-transfer tasks, and evidence of far-transfer of training effects in four of five far-transfer tasks. Frontal region changes indicated normalization of atypical EEG features with reduced delta and increased alpha activity. It is concluded that technology developments provide an interesting a vehicle for delivering interventions and that, while further research is needed, combined WM, IC, and neurofeedback training can reduce AD/HD symptom severity in children with AD/HD and may also be beneficial to children with subclinical AD/HD.

Variation in Latent Classes of Adult Attention-Deficit Hyperactivity Disorder by Sex and Environmental Adversity

OBJECTIVE

The findings of genetic, imaging and neuropsychological studies of attention-deficit hyperactivity disorder (ADHD) are mixed. To understand why this might be the case we use both dimensional and categorical symptom measurement to provide alternate and detailed perspectives of symptom expression.

METHOD

Interviewers collected ADHD, conduct problems (CP) and sociodemographic data from 3793 twins and their siblings aged 22 to 49 (M = 32.6). We estimate linear weighting of symptoms across ADHD and CP items. Latent class analyses and regression describe associations between measured variables, environmental risk factors and subsequent disadvantage. Additionally, the clinical relevance of each class was estimated.

RESULTS

Five classes were found for women and men; few symptoms, hyperactive-impulsive, CP, inattentive, combined symptoms with CP. Women within the inattentive class reported more symptoms and reduced emotional health when compared to men and to women within other latent classes. Women and men with combined ADHD symptoms reported comorbid conduct problems but those with either inattention or hyperactivity-impulsivity only did not.

CONCLUSION

The dual perspective of dimensional and categorical measurement of ADHD provides important detail about symptom variation across sex and with environmental covariates.

A Developmental Psychopathology Perspective on ADHD and Comorbid Conditions: The Role of Emotion Regulation

Research investigating attention-deficit/hyperactivity disorder (ADHD) and co-occurring disorders such as oppositional defiant disorder, conduct disorder, anxiety, and depression has surged in popularity; however, the developmental relations between ADHD and these comorbid conditions remain poorly understood. The current paper uses a developmental psychopathology perspective to examine conditions commonly comorbid with ADHD during late childhood through adolescence. First, we present evidence for ADHD and comorbid disorders. Next, we discuss emotion regulation and its associations with ADHD. The role of parenting behaviors in the development and maintenance of emotion regulation difficulties and comorbid disorders among children with ADHD is explored. An illustrative example of emotion regulation and parenting over the course of development is provided to demonstrate bidirectional relations among these constructs. We then present an integrated conceptual model of emotion regulation as a shared risk process that may lead to different comorbid conditions among children with ADHD. Implications and directions for future research are presented.

Latent profile analysis of neuropsychological measures to determine preschoolers' risk for ADHD

BACKGROUND

Hyperactive/Inattentive preschool children show clear evidence of neuropsychological dysfunction. We examined whether patterns and severity of test scores could reliably identify subgroups of preschoolers with differential risk for ADHD during school-age.

METHOD

Typically developing (TD: n = 76) and Hyperactive/Inattentive (HI: n = 138) 3-4 year olds were assessed annually for 6 years (T1-T6). Latent profile analysis (LPA) was used to form subgroups among the HI group based on objective/neuropsychological measures (NEPSY, Actigraph and Continuous Performance Test). Logistic regression assessed the predictive validity of empirically formed subgroups at risk for ADHD diagnosis relative to the TD group and to each other from T2 to T6.

RESULTS

Latent profile analysis yielded two subgroups of HI preschoolers: (a) selectively weak Attention/Executive functions, and (b) pervasive neuropsychological dysfunction across all measures. Both subgroups were more likely to have ADHD at all follow-up time-points relative to the TD group (OR range: 11.29-86.32), but there were no significant differences between the LPA-formed subgroups of HI children at any time-point.

CONCLUSIONS

Objective/neuropsychological measures distinguish HI preschoolers from their TD peers, but patterns and severity of neuropsychological dysfunction do not predict risk for ADHD during school-age. We hypothesize that trajectories in at-risk children are influenced by subsequent environmental and neurodevelopmental factors, raising the possibility that they are amenable to early intervention.

Classes of oppositional-defiant behavior: concurrent and predictive validity

BACKGROUND

Oppositional defiant disorder (ODD) has components of both irritability and defiance. It remains unclear whether children with variation in these domains have different adult outcomes. This study examined the concurrent and predictive validity of classes of oppositional defiant behavior.

METHODS

Latent class analysis was performed on the oppositional defiant problems scale of the Child Behavior Checklist in two samples, one in the US (the Achenbach Normative Sample, N = 2029) and one in the Netherlands (the Zuid-Holland Study, N = 2076). A third sample of American children (The Vermont Family Study, N = 399) was examined to determine concurrent validity with DSM diagnoses. Predictive validity over 14 years was assessed using the Zuid-Holland Study.

RESULTS

Four classes of oppositional defiant problems were consistent in the two latent class analyses: No Symptoms, All Symptoms, Irritable, and Defiant. Individuals in the No Symptoms Class were rarely diagnosed concurrently with ODD or any future disorder. Individuals in the All Symptoms Class had an increased frequency of concurrent childhood diagnosis of ODD and of violence in adulthood. Subjects in the Irritable Class had low concurrent diagnosis of ODD, but increased odds of adult mood disorders. Individuals in the Defiant Class had low concurrent diagnosis of ODD, but had increased odds of violence as adults.

CONCLUSIONS

Only children in the All Symptoms class were likely to have a concurrent diagnosis of ODD. Although not diagnosed with ODD, children in the Irritable Class were more likely to have adult mood disorders and children in the Defiant Class were more likely to engage in violent behavior.

Cross-informant agreement on child and adolescent withdrawn behavior: a latent class approach

Withdrawn behavior (WB) relates to many developmental outcomes, including pervasive developmental disorders, anxiety, depression, psychosis, personality disorders and suicide. No study has compared the latent profiles of different informants' reports on WB. This study uses multi-informant latent class analyses (LCA) of the child behavior checklist (CBCL), teacher report form (TRF) and youth self-report (YSR) to examine phenotypic variance in WB. LCA was applied to the CBCL, TRF and YSR of 2,031 youth (ages 6-18); of which 276 children were clinically-referred. A 4-class solution for the CBCL and 3-class solutions for the YSR and TRF were optimal. The CBCL yielded low symptoms, predominantly shy or secretive moderate symptoms, and all symptoms classes. The TRF lacked the moderate--secretive class, and the YSR lacked the moderate--shy class. Agreement was low. LCA shows similar structure of withdrawn behavior across informants but characterizations of moderate WB vary.

Separating the domains of oppositional behavior: comparing latent models of the conners' oppositional subscale

OBJECTIVE

Although oppositional defiant disorder (ODD) is usually considered the mildest of the disruptive behavior disorders, it is a key factor in predicting young adult anxiety and depression and is distinguishable from normal childhood behavior. In an effort to understand possible subsets of oppositional defiant behavior (ODB) that may differentially predict outcome, we used latent class analysis of mother report on the Conners' Parent Rating Scales Revised Short Forms (CPRS-R:S).

METHOD

Data were obtained from mother report for Dutch twins (7 years old, n = 7,597; 10 years old, n = 6,548; and 12 years old, n = 5,717) from the Netherlands Twin Registry. Samples partially overlapped at ages 7 and 10 years (19% overlapping) and at ages 10 and 12 years (30% overlapping), but not at ages 7 and 12 years. Oppositional defiant behavior was measured using the six-item Oppositional subscale of the CPRS-R:S. Multilevel LCA with robust standard error estimates was performed using the Latent Gold program to control for twin-twin dependence in the data. Class assignment across ages was determined and an estimate of heritability for each class was calculated. Comparisons with maternal report Child Behavior Checklist (CBCL) scores were examined using linear mixed models at each age, corrected for multiple comparisons.

RESULTS

The LCA identified an optimal solution of four classes across age groups. Class 1 was associated with no or low symptom endorsement (69-75% of the children); class 2 was characterized by defiance (11-12%); class 3 was characterized by irritability (9-11%); and class 4 was associated with elevated scores on all symptoms (5-8%). Odds ratios for twins being in the same class at each successive age point were higher within classes across ages than between classes. Heritability within the two "intermediate" classes was nearly as high as for the class with all symptoms, except for boys at age 12. Children in the Irritable class were more likely to have mood symptoms on the CBCL scales than children in the Defiant class but demonstrated similar scores on aggression and externalizing scales. Children in the All Symptoms class were higher in both internalizing and externalizing scales and subscales.

CONCLUSIONS

The LCA indicates four distinct latent classes of oppositional defiant behavior, in which the distinguishing feature between the two intermediate classes (classes 2 and 3) is the level of irritability and defiance. Implications for the longitudinal course of these symptoms, association with other disorders, and genetics are discussed.

The latent classes of subclinical ADHD symptoms: convergences of multiple informant reports

The purpose of the present study was to conduct latent class analysis on the Hyperactivity scale of the Strengths and Difficulties Questionnaire in order to identify distinct subgroups of subclinical ADHD in a multi-informant framework. We hypothesized a similar structure between teachers and parents, and differences in symptom severity across latent classes. Data was collected from a non-referred sample of children aged 8-13 years. We performed latent class analyses on parent (n = 383) and teacher (n = 391) ratings of the Hyperactivity scale items from both versions of the questionnaire. Those children who had ratings from both informants (n = 272) were included in the cross-informant analyses, in which the similar or equivalent classes across raters were determined. A three-class solution for parent report and a five-class solution for teacher report emerged in the subsample of boys. For girls, a three-class structure for parents and a four-class structure for teachers were optimal. Besides non-symptomatic groups, mild and severe combined classes, mild inattentive-impulsive classes, and among boys, a mild hyperactive-impulsive class was obtained. The cross-informant analyses demonstrated that quite similar subgroups were detached regardless of informant; however, the teacher classes were somewhat more elaborated. The results are in line with the previous latent class analytic studies, and support the combination of dimensional and categorical approaches. The importance of milder symptoms and sub-threshold ADHD categories are emphasized for the fields of neuropsychology, neuroscience, and education, as well as for diagnosis and personalized treatment.

Abilities of preschoolers: comparing different tools

Background

There is a strong need for studies evaluating tests in terms both of psychometric properties (i.e. their efficacy or ability to be helpful in reaching a diagnosis) and of their cost-effectiveness (i.e. their efficiency). These data are essential for planning a correct evaluation to identify children's needs (both educational and abilitative).

Methods

We evaluated 58 children attending for the first time the last year of the Scuola dell'Infanzia. Parental view was obtained with Child Behaviour Check-List and Conners' Rating Scales - Revised, and family socio-economic status was evaluated using Hollingshead's Four Factor Index; teacher compiled the IPDA questionnaire; children were administered Raven's Progressive Matrices, Modified Bell Cancellation Test, BVN 5-11 (a neuropsychological battery).

Results

A correlational analysis was conducted using Spearman's Rho (since variables were not normally distributed). These asymptomatic children show a good global cognitive functioning, but also a deficit of attention and of Executive Functions. Some of the tests used seem more cost-effective than others and there are some redundancies in information obtained.

Conclusions

Our data show that there are significant correlations between different neuropsychological and behavioural measures. It is therefore possible to rationalize diagnostic protocols without a significant information reduction. A deeper analysis will require a preliminary definition of the psychometric properties of used tools.

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.

A latent class analysis of DSM-IV pathological gambling criteria in a nationally representative British sample

This study identified empirically derived subtypes of gamblers based on the Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) diagnostic criteria for pathological gambling disorder (PGD). Data from the gamblers (n=5644) who participated in the 2007 British Gambling Prevalence Survey (BGPS) were analysed using latent class analysis. Common socio-demographic correlates of PGD were subsequently assessed across the classes. Three distinct groups or classes of gamblers emerged. The majority of the sample (88.9%) was assigned to a 'non-problematic gambler' class. A second 'preoccupied chaser' class contained a significant percentage of gamblers (9.7%) who reported symptoms such as a preoccupation with gambling and engaging in chasing loses. Approximately 1.4% of gamblers were classified into an 'antisocial impulsivist gambler' class. Males, non-Whites and smokers were all more likely to be preoccupied chasers or antisocial impulsivist gamblers, rather than non-problematic gamblers. The current findings revealed that the gambling subtypes identified in the 2007 BGPS largely differed in relation to the severity, rather than the type, of symptoms experienced. These findings present a useful and clinically meaningful typology of individuals with PGD that may be examined further in both research and clinical settings.

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.

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.

Latent class analysis of the Child Behavior Checklist Obsessive-Compulsive Scale

The Obsessive-Compulsive Scale (OCS) of the Child Behavior Checklist (CBCL) predicts obsessive-compulsive disorder and is highly heritable. Latent class analysis (LCA) of the OCS was used to identify profiles within this 8-item scale and to examine heritability of those profiles. The LCA was performed on maternal CBCL reports of their 6- to 18-year-old children from 2 US nationally representative samples from 1989 (n = 2475, 50% male) and 1999 (n = 2029, 53% male) and from Dutch twins in the Netherlands Twin Registry at ages 7 (n = 10 194, 49.3% male), 10 (n = 6448, 48.1% male), and 12 (n = 3674, 48.6% male) years. The heritability of the resultant classes was estimated using odds ratios of twin membership across classes. A 4-class solution fitted all samples best. The resulting classes were a "No or Few Symptoms" class, a "Worries and Has to Be Perfect" class, a "Thought Problems" class, and an "OCS" class. Within-class odds ratios were higher than across-class odds ratios and were higher for monozygotic than dizygotic twins. We conclude that LCA identifies an OCS class and that class is highly heritable using across-twin comparisons.

Latent class subtyping of attention-deficit/hyperactivity disorder and comorbid conditions

OBJECTIVE

Genetic studies of attention-deficit/hyperactivity disorder (ADHD) generally use discrete DSM-IV subtypes to define diagnostic status. To improve correspondence between phenotypic variance and putative susceptibility genes, multivariate classification methods such as latent class analysis (LCA) have been proposed. The aim of this study was to perform LCA in a sample of 1,010 individuals from a nationwide recruitment of unilineal nuclear families with at least one child with ADHD and another child either affected or clearly unaffected.

METHOD

LCA models containing one through 10 classes were fitted to data derived from all DSM-IV symptoms for ADHD, oppositional defiant disorder, and conduct disorder (CD), as well as seven items that screen for anxiety and depression from the National Initiative for Children's Healthcare Quality Vanderbilt Assessment Scale for Parents.

RESULTS

We replicated six to eight statistically significantly distinct clusters, similar to those described in other cross-cultural studies, mostly stable when comorbidities are included. For all age groups, anxiety and depression are strongly related to Inattentive and Combined types. Externalizing symptoms, especially CD, are strongly associated with the Combined type of ADHD. Oppositional defiant disorder symptoms in young children are associated with either conduct disorder or anxiety-related symptoms.

CONCLUSIONS

Methods such as LCA allow inclusion of information about comorbidities to be quantitatively incorporated into genetic studies. LCA also permits incorporation of milder but still impairing phenotypes than are allowed using the DSM-IV. Such methods may be essential for analyses of large multicenter datasets and relevant for future clinical classifications. This population-based ADHD classification may help resolve the contradictory results presented in molecular genetic studies.

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.

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.