Are there distinct cognitive and motivational sub-groups of children with ADHD?

BACKGROUND: Attention-deficit/hyperactivity disorder (ADHD) is proposed to be a neuropsychologically heterogeneous disorder that encompasses two distinct sub-groups, one with executive function (EF) deficits and one with delay aversion (DA). However, such claims have often been based on studies that have operationalized neuropsychological deficits using a categorical approach - using intuitive but rather arbitrary, clinical cut-offs. The current study applied an alternative empirical approach to sub-grouping in ADHD, latent profile analysis (LPA), and attempted to validate emerging subgroups through clinically relevant correlates. METHODS: One-hundred medication-naïve children with ADHD and 96 typically developing children (6-14 years) completed nine EF and three DA tasks as well as an odor identification test. Parents and teachers provided reports of the children's behavior (ADHD and EF). Models of the latent structure of scores on EF and DA tests were contrasted using confirmatory factor analysis (CFA). LPA was carried out based on factor scores from the CFA and sub-groups were compared in terms of odor identification and behavior. RESULTS: A model with one DA and two EF factors best fit the data. LPA resulted in four sub-groups that differed in terms of general level of neuropsychological performance (ranging from high to very low), odor identification, and behavior. The sub-groups did not differ in terms of the relative EF and DA performance. Results in the ADHD group were replicated in the control group. CONCLUSIONS: While EF and DA appear to be dissociable constructs; they do not yield distinct sub-groups when sub-grouping is based on a statistical approach such as LPA.

An international clinical study of ability and disability in ADHD using the WHO-ICF framework.

This is the fourth and final study designed to develop International Classification of Functioning, Disability and Health (ICF, and children and youth version, ICF-CY) core sets for attention-deficit hyperactivity disorder (ADHD). To investigate aspects of functioning and environment of individuals with ADHD as documented by the ICF-CY in clinical practice settings. An international cross-sectional multi-centre study was applied, involving nine units from eight countries: Denmark, Germany, India, Italy, Portugal, Saudi Arabia, Sweden and Taiwan. Clinicians and clinical researchers rated the functioning level of 112 children, adolescents and adults with ADHD using the extended ICF-CY checklist version 2.1a. The ratings were based on a variety of information sources, such as medical records, medical history, clinical observations, clinical questionnaires, psychometric tests and structured interviews with participants and family members. In total, 113 ICF-CY categories were identified, of which 50 were related to the activities and participation, 33 to environmental factors and 30 to body functions. The clinical study also yielded strengths related to ADHD, which included temperament and personality functions and recreation and leisure. The study findings endorse the complex nature of ADHD, as evidenced by the many functional and contextual domains impacted in ADHD. ICF-CY based tools can serve as foundation for capturing various functional profiles and environmental facilitators and barriers. The international nature of the ICF-CY makes it possible to develop user-friendly tools that can be applied globally and in multiple settings, ranging from clinical services and policy-making to education and research.

Towards an ICF core set for ADHD: a worldwide expert survey on ability and disability.

This is the second in a series of four empirical studies designed to develop International Classification of Functioning, Disability and Health (ICF and Children and Youth version, ICF-CY) core sets for attention deficit hyperactivity disorder (ADHD). The objective of this stage was to gather the opinions from international experts on which ability and disability concepts were considered relevant to functioning in ADHD. An email-based survey was carried out amongst international experts in ADHD. Relevant functional ability and disability concepts were extracted from their responses and linked to the ICF/-CY categories by two independent researchers using a standardised linking procedure. 174 experts from 11 different disciplines and 45 different countries completed the survey. Meaningful concepts identified in their responses were linked to 185 ICF/-CY categories. Of these, 83 categories were identified by at least 5 % of the experts and considered the most relevant to ADHD: 30 of these were related to Body functions (most identified: attention functions, 85 %), 30 to Activities and Participation (most identified: school education, 52 %), 20 to Environmental factors (most identified: support from immediate family, 61 %), and 3 to Body structures (most identified: structure of brain, 83 %). Experts also provided their views on particular abilities related to ADHD, naming characteristics such as high-energy levels, flexibility and resiliency. Gender differences in the expression of ADHD identified by experts pertained mainly to females showing more internalising (e.g. anxiety, low self-esteem) and less externalising behaviours (e.g. hyperactivity), leading to a risk of late- and under-diagnosis in females. Results indicate that the impact of ADHD extends beyond the core symptom domains, into all areas of life and across the lifespan. The current study in combination with three additional preparatory studies (comprehensive scoping review, focus groups, clinical study) will provide the scientific basis to define the ADHD ICF/-CY core sets for multi-purpose use in basic and applied research and every day clinical practice.

A comprehensive scoping review of ability and disability in ADHD using the International Classification of Functioning, Disability and Health-Children and Youth Version (ICF-CY).

This is the first in a series of four empirical investigations to develop International Classification of Functioning, Disability and Health (ICF) Core Sets for Attention Deficit Hyperactivity Disorder (ADHD). The objective here was to use a comprehensive scoping review approach to identify the concepts of functional ability and disability used in the scientific ADHD literature and link these to the nomenclature of the ICF-CY. Systematic searches were conducted using Medline/PubMed, PsycINFO, ERIC and Cinahl, to extract the relevant concepts of functional ability and disability from the identified outcome studies of ADHD. These concepts were then linked to ICF-CY by two independent researchers using a standardized linking procedure. Data from identified studies were analysed until saturation of ICF-CY categories was reached. Eighty studies were included in the final analysis. Concepts contained in these studies were linked to 128 ICF-CY categories. Of these categories, 68 were considered to be particularly relevant to ADHD (i.e., identified in at least 5 % of the studies). Of these, 32 were related to Activities and participation, 31 were related to Body functions, and five were related to environmental factors. The five most frequently identified categories were school education (53 %), energy and drive functions (50 %), psychomotor functions (50 %), attention functions (49 %), and emotional functions (45 %). The broad variety of ICF-CY categories identified in this study underlines the necessity to consider ability and disability in ADHD across all dimensions of life, for which the ICF-CY provides a valuable and universally applicable framework. These results, in combination with three additional preparatory studies (expert survey, focus groups, clinical study), will provide a scientific basis to define the ICF Core Sets for ADHD for multi-purpose use in basic and applied research, and every day clinical practice.

Colour vision in ADHD: part 1--testing the retinal dopaminergic hypothesis.

OBJECTIVES: To test the retinal dopaminergic hypothesis, which posits deficient blue color perception in ADHD, resulting from hypofunctioning CNS and retinal dopamine, to which blue cones are exquisitely sensitive. Also, purported sex differences in red color perception were explored. METHODS: 30 young adults diagnosed with ADHD and 30 healthy young adults, matched on age and gender, performed a psychophysical task to measure blue and red color saturation and contrast discrimination ability. Visual function measures, such as the Visual Activities Questionnaire (VAQ) and Farnsworth-Munsell 100 hue test (FMT), were also administered. RESULTS: Females with ADHD were less accurate in discriminating blue and red color saturation relative to controls but did not differ in contrast sensitivity. Female control participants were better at discriminating red saturation than males, but no sex difference was present within the ADHD group. CONCLUSION: Poorer discrimination of red as well as blue color saturation in the female ADHD group may be partly attributable to a hypo-dopaminergic state in the retina, given that color perception (blue-yellow and red-green) is based on input from S-cones (short wavelength cone system) early in the visual pathway. The origin of female superiority in red perception may be rooted in sex-specific functional specialization in hunter-gather societies. The absence of this sexual dimorphism for red colour perception in ADHD females warrants further investigation.

Color vision in ADHD: part 2--does attention influence color perception?

BACKGROUND: To investigate the impact of exogenous covert attention on chromatic (blue and red) and achromatic visual perception in adults with and without Attention Deficit Hyperactivity Disorder (ADHD). Exogenous covert attention, which is a transient, automatic, stimulus-driven form of attention, is a key mechanism for selecting relevant information in visual arrays. METHODS: 30 adults diagnosed with ADHD and 30 healthy adults, matched on age and gender, performed a psychophysical task designed to measure the effects of exogenous covert attention on perceived color saturation (blue, red) and contrast sensitivity. RESULTS: The effects of exogenous covert attention on perceived blue and red saturation levels and contrast sensitivity were similar in both groups, with no differences between males and females. Specifically, exogenous covert attention enhanced the perception of blue saturation and contrast sensitivity, but it had no effect on the perception of red saturation. CONCLUSION: The findings suggest that exogenous covert attention is intact in adults with ADHD and does not account for the observed impairments in the perception of chromatic (blue and red) saturation.

Development of ICF Core Sets to standardize assessment of functioning and impairment in ADHD: the path ahead.

In the study of health and quality of life in attention deficit/hyperactivity disorder (ADHD), it is of paramount importance to include assessment of functioning. The International Classification of Functioning, Disability and Health (ICF) provides a comprehensive, universally accepted framework for the description of functioning in relation to health conditions. In this paper, the authors outline the process to develop ICF Core Sets for ADHD. ICF Core Sets are subgroups of ICF categories selected to capture the aspects of functioning that are most likely to be affected in specific disorders. The ICF categories that will be included in the ICF Core Sets for ADHD will be determined at an ICF Core Set Consensus Conference, wherein evidence from four preliminary studies (a systematic review, an expert survey, a patient and caregiver qualitative study, and a clinical cross-sectional study) will be integrated. Comprehensive and Brief ICF Core Sets for ADHD will be developed with the goal of providing useful standards for research and clinical practice, and to generate a common language for the description of functioning in ADHD in different areas of life and across the lifespan.

Sustained impact of inattention and hyperactivity-impulsivity on peer problems: mediating roles of prosocial skills and conduct problems in a community sample of children.

This prospective 2-year longitudinal study tested whether inattentive and hyperactive/impulsive symptom dimensions predicted future peer problems, when accounting for concurrent conduct problems and prosocial skills. A community sample of 492 children (49 % female) who ranged in age from 6 to 10 years (M = 8.6, SD = .93) was recruited. Teacher reports of children's inattention, and hyperactivity/impulsivity symptoms, conduct problems, prosocial skills and peer problems were collected in two consecutive school years. Elevated inattention and hyperactivity/impulsivity in Year-1 predicted greater peer problems in Year-2. Conduct problems in the first and second years of the study were associated with more peer problems, and explained a portion of the relationship between inattention and hyperactivity/impulsivity with peer problems. However, prosocial skills were associated with fewer peer problems in children with elevated inattention and hyperactivity/impulsivity. Inattention and hyperactivity/impulsivity have negative effects on children's peer functioning after 1-year, but concurrent conduct problems and prosocial skills have important and opposing impacts on these associations.

Resting state EEG oscillatory power differences in ADHD college students and their peers.

BACKGROUND: Among the most robust neural abnormalities differentiating individuals with Attention-Deficit/Hyperactivity Disorder (ADHD) from typically developing controls are elevated levels of slow oscillatory activity (e.g., theta) and reduced fast oscillatory activity (e.g., alpha and beta) during resting-state electroencephalography (EEG). However, studies of resting state EEG in adults with ADHD are scarce and yield inconsistent findings. METHODS: EEG profiles, recorded during a resting-state with eyes-open and eyes-closed conditions, were compared for college students with ADHD (n = 18) and a nonclinical comparison group (n = 17). RESULTS: The ADHD group showed decreased power for fast frequencies, especially alpha. This group also showed increased power in the slow frequency bands, however, these effects were strongest using relative power computations. Furthermore, the theta/beta ratio measure was reliably higher for the ADHD group. All effects were more pronounced for the eyes-closed compared to the eyes-open condition. Measures of intra-individual variability suggested that brains of the ADHD group were less variable than those of controls. CONCLUSIONS: The findings of this pilot study reveal that college students with ADHD show a distinct neural pattern during resting state, suggesting that oscillatory power, especially alpha, is a useful index for reflecting differences in neural communication of ADHD in early adulthood.

The hierarchical factor model of ADHD: invariant across age and national groupings?

OBJECTIVE: To examine the factor structure of attention-deficit/hyperactivity disorder (ADHD) in a clinical sample of 1,373 children and adolescents with ADHD and their 1,772 unselected siblings recruited from different countries across a large age range. Hierarchical and correlated factor analytic models were compared separately in the ADHD and sibling samples, across three different instruments and across parent and teacher informants. Specific consideration was given to factorial invariance analyses across different ages and different countries in the ADHD sample. METHOD: A sample of children and adolescents between 5 and 17 years of age with ADHD and their unselected siblings was assessed. Participants were recruited from seven European countries and Israel. ADHD symptom data came from a clinical interview with parents Parental Account of Childhood Symptoms and questionnaires from parents and teachers (Conners Parent and Teacher). RESULTS: A hierarchical general factor model with two specific factors best represented the structure of ADHD in both the ADHD and unselected sibling groups, and across informants and instruments. The model was robust and invariant with regard to age differences in the ADHD sample. The model was not strongly invariant across different national groups in the ADHD sample, likely reflecting severity differences across the different centers and not any substantial difference in the clinical presentation of ADHD. CONCLUSIONS: The results replicate previous studies of a model with a unitary ADHD component and separable specific traits of inattention and hyperactivity/impulsivity. The unique contribution of this study was finding support for this model across a large developmental and multinational/multicultural sample and its invariance across ages.

Executive function and suicidal risk in women with Borderline Personality Disorder.

A range of executive function (EF) deficits have been associated with Borderline Personality (BPD), a disorder characterized by high rates of suicide. However, the role of EF and suicide risk in BPD has not been examined. This exploratory study compared working memory, Stroop interference, motor inhibition (SSRT) and Iowa Gambling Task (IGT) decision making performance in 42 women with BPD and 41 healthy controls. The sensitivity of EF to suicidal risk as assessed by the Suicide Behaviour Questionnaire-R (Osman et al., 2001) was also tested. Women with BPD performed similar to controls on all EF except decision making. Weaker Stroop interference control, however, was the only significant EF contributor to suicide risk, demonstrating near equivalent contributions to that of depression. EF and depression collectively explained 34% of the adjusted variance in total suicide risk. Contrary to expectations, IGT decision making and motor inhibition were not associated with overall suicide risk. Only Stroop interference control contributed significantly to lifetime suicide intent/attempt beyond depression or BPD severity. As prior suicide attempt remains the strongest predictor of future attempt (Soloff et al., 2003), the sensitivity of stroop performance to suicidal risk may be clinically important. Interference control may represent a "diathesis" for suicide that is independent of psychiatric diagnoses.

Visuospatial Working Memory Capacity in the Brain After Working Memory Training in College Students With ADHD: A Randomized Controlled Trial.

Objective: ADHD has been associated with persistent problems of working memory. This study investigated the efficacy of an intensive and adaptive computerized working memory treatment (CWMT) at behavioral and neural levels. Method: College students (n = 89; 40 females) with ADHD were randomized into a standard-length CWMT (45 min/session, 25 sessions, n = 29), shortened-length CWMT (15 min/session, 25 sessions, n = 32), and a waitlist group (n = 28). Both CWMT groups received treatment for 5 days a week for 5 weeks. Lab sessions before and after CWMT assessed electroencephalography (EEG) indicators of working memory, behavioral indicators of working memory performance, and ADHD symptomatology. Results: No evidence was found for neural or any other behavioral transfer effects of improvement for the CWMT treatment groups over the active control or waitlist group. Conclusion: Our study does not provide evidence for the benefits of CWMT at neural or behavioral levels.

Network analysis of narrative discourse and attention-deficit hyperactivity symptoms in adults.

Previous research investigating language in attention-deficit hyperactivity disorder (ADHD) has demonstrated several deficits in many aspects. However, no previous study employed quantitative methodology providing objective measures that could be compared among different studies with diverse samples. To fill this gap, we used network analysis to investigate how ADHD symptomatology impacts narrative discourse, a complex linguistic task considered to be an ecological measure of language. Fifty-eight adults (34 females and 24 males) with a mean age of 26 years old and a mean of 17 years of educational level were administered the Adult Self-Rating Scale for ADHD symptomatology. They also completed the State-Trait Anxiety Inventory, the Beck Depression Inventory and the Urgency, Premeditation, Perseverance, Sensation Seeking Behavior Scale. Intelligence quotient was calculated. Individuals were asked to tell a story based on a wordless picture book. Speech was recorded and transcribed as an input to SpeechGraphs software. Parameters were total number of words (TNW), number of loops of one node (L1), repeated edges (RE), largest strongly connected component (LSC) and average shortest path (ASP). Verbosity was controlled. Statistical analysis was corrected for multiples comparisons and partial correlations were performed for confounding variables. After controlling for anxiety, depression, IQ, and impulsiveness ADHD symptomatology was positively correlated with L1 and negatively correlated with LSC. TNW was positively correlated with ADHD symptoms. In a subdomain analysis, both inattention and hyperactivity-impulsivity were negatively correlated with LSC. Only hyperactivity-impulsivity positively correlated with TNW and L1. Results indicated a correlation between ADHD symptoms and lower connectedness in narrative discourse (as indicated by higher L1 and lower LSC), as well as higher total number of words (TNW). Our results suggest that the higher the number of ADHD symptoms, the less connectivity among words, and a higher number of words in narrative discourse.

Mathematics anxiety in children with developmental dyscalculia.

BACKGROUND: Math anxiety, defined as a negative affective response to mathematics, is known to have deleterious effects on math performance in the general population. However, the assumption that math anxiety is directly related to math performance, has not yet been validated. Thus, our primary objective was to investigate the effects of math anxiety on numerical processing in children with specific deficits in the acquisition of math skills (Developmental Dyscalculia; DD) by using a novel affective priming task as an indirect measure. METHODS: Participants (12 children with DD and 11 typically-developing peers) completed a novel priming task in which an arithmetic equation was preceded by one of four types of priming words (positive, neutral, negative or related to mathematics). Children were required to indicate whether the equation (simple math facts based on addition, subtraction, multiplication or division) was true or false. Typically, people respond to target stimuli more quickly after presentation of an affectively-related prime than after one that is unrelated affectively. RESULT: Participants with DD responded faster to targets that were preceded by both negative primes and math-related primes. A reversed pattern was present in the control group. CONCLUSION: These results reveal a direct link between emotions, arithmetic and low achievement in math. It is also suggested that arithmetic-affective priming might be used as an indirect measure of math anxiety.

Validating neuropsychological subtypes of ADHD: how do children with and without an executive function deficit differ?

OBJECTIVE: The study investigates behavioural, academic, cognitive, and motivational aspects of functioning in school-age children with attention-deficit/hyperactivity disorder (ADHD) with and without an executive function deficit (EFD). METHOD: Children with ADHD--EFD (n = 22) and children with ADHD + EFD (n = 26) were compared on aspects of ADHD behaviour, school functioning, general cognitive ability, intra-individual response variability, affective decision-making, and delay aversion. RESULTS: Children with ADHD--EFD and children with ADHD + EFD were comparable in terms of ADHD symptomatology and school functioning. However, children with ADHD + EFD had significantly lower IQ and more intra-individual response variability than no EFD counterparts. Children with ADHD alone appeared more delay averse on the C-DT task than children with ADHD + EFD. CONCLUSIONS: Some children with ADHD were primarily characterised by problems with executive functions and variability others by problems with delay aversion supporting multiple pathway models of ADHD. Given the exploratory nature of the study, results are in need of replication.

Diagnostic instability of DSM-IV ADHD subtypes: effects of informant source, instrumentation, and methods for combining symptom reports.

Using data from 123 children (aged 6-12 years) referred consecutively to a pediatric neuropsychiatry clinic by community physicians for assessment of Attention-Deficit/Hyperactivity Disorder (ADHD) and related problems, we investigated the effects of informant (parent, teacher), tool (interview, rating scale), and method for combining symptom reports ("and," "or" algorithms), on the diagnosis of ADHD and its subtypes. Results indicated that as many as 50% of cases were reclassified from one subtype to another, depending on whether information was derived from one or two informants, a semistructured clinical interview and/or rating scale, and the algorithm used to combine informant reports. We conclude that the diagnosis of DSM-IV ADHD subtypes is capricious in that it is influenced by clinicians' decisions regarding informants, instrumentation, and method for aggregating information across informants and instruments.

What is to be the fate of ADHD subtypes? An introduction to the special section on research on the ADHD subtypes and implications for the DSM-V.

One of the major questions facing the taxonomy of attention deficit/hyperactivity disorder is how to handle its marked heterogeneity in symptom presentation and impairments. The current methods for defining subtypes have been widely criticized but it is unclear if the subtype concept is fundamentally flawed or whether it is the methods for designating subtypes in current diagnostic approaches which are flawed. The current article is an introduction to a special section in which four articles provide data illustrating the complexity of considerations involving subtyping of attention deficit/hyperactivity disorder and provide ideas for alternatives that warrant further discussion and examination.

Association of reading disabilities with regions marked by acetylated H3 histones in KIAA0319.

Reading disabilities (RDs) have been associated with chromosome 6p with recent studies pointing to two genes, DCDC2 and KIAA0319. In this study, markers across the 6p region were tested for association with RD. Our strongest findings were for association with markers in KIAA0319, although with the opposite alleles compared with a previous study. We also found association with markers in VMP, but not with DCDC2. Current evidence indicates that differential regulation of KIAA0319 and DCDC2 contributes to RD, thus we used chromatin immunoprecipitation coupled with genomic tiling arrays (ChIP-chip) to map acetylated histones, a molecular marker for regulatory elements, across a 500 kb genomic region covering the RD locus on 6p. This approach identified several regions marked by acetylated histones that mapped near associated markers, including intron 7 of DCDC2 and the 5' region of KIAA0319. The latter is located within the 70 kb region previously associated with differential expression of KIAA0319. Interestingly, five markers associated with RD in independent studies were also located within the 2.7 kb acetylated region, and six additional associated markers, including the most significant one in this study, were located within a 22 kb haplotype block that encompassed this region. Our data indicates that this putative regulatory region is a likely site of genetic variation contributing to RD in our sample, further narrowing the candidate region.

Profiles of Co-Occurring Difficulties Identified Through School-Based Screening.

Objective: This study used latent class analysis to identify patterns of co-occurrence among common childhood difficulties (inattention/hyperactivity, internalizing, externalizing, peer problems, and reading difficulties). Method: Parents and teachers of 501 children ages 6 to 9 provided mental health and social ratings, and children completed a reading task. Results: Four latent classes were identified in the analysis of parent ratings and reading: one with inattention/hyperactivity, externalizing, peer problems, and internalizing difficulties; one with inattention/hyperactivity and reading difficulties; one with internalizing and peer problems; and one normative class. The analysis of teacher ratings and reading also identified four latent classes: one with inattention/hyperactivity and externalizing, one with inattention/hyperactivity and reading difficulties, one with internalizing problems, and one normative class. Children in latent classes characterized by one or more difficulties were more impaired than children in the normative latent class 1 year later. Conclusion: The results highlight the need for multifaceted interventions.