Neurocognitive Profiles in Children With ADHD and Their Predictive Value for Functional Outcomes

Data-driven profiles of attention-deficit/hyperactivity disorder using objective and ecological measures of attention, distractibility, and hyperactivity

In the past two decades, the traditional nosology of attention-deficit/hyperactivity disorder (ADHD) has been criticized for having insufficient discriminant validity. In line with current trends, in the present study, we combined a data-driven approach with the advantages of virtual reality aiming to identify novel behavioral profiles of ADHD based on ecological and performance-based measures of inattention, impulsivity, and hyperactivity. One hundred and ten Spanish-speaking participants (6-16 years) with ADHD (medication-naïve, n = 57) and typically developing participants (n = 53) completed AULA, a continuous performance test embedded in virtual reality. We performed hybrid hierarchical k-means clustering methods over the whole sample on the normalized t-scores of AULA main indices. A five-cluster structure was the most optimal solution. We did not replicate ADHD subtypes. Instead, we identified two clusters sharing clinical scores on attention indices, susceptibility to distraction, and head motor activity, but with opposing scores on mean reaction time and commission errors; two clusters with good performance; and one cluster with average scores but increased response variability and slow RT. DSM-5 subtypes cut across cluster profiles. Our results suggest that latency of response and response inhibition could serve to distinguish among ADHD subpopulations and guide neuropsychological interventions. Motor activity, in contrast, seems to be a common feature among ADHD subgroups. This study highlights the poor feasibility of categorical systems to parse ADHD heterogeneity and the added value of data-driven approaches and VR-based assessments to obtain an accurate characterization of cognitive functioning in individuals with and without ADHD.

Identifying subgroups of attention-deficit/hyperactivity disorder from the psychopathological and neuropsychological profiles

The Research Domain Criteria (RDoC) advocates the dimensional approach in characterizing mental disorders. We followed RDoC to characterize children with ADHD using profiling based on the cognitive and psychopathological domains. We aimed to identify and validate ADHD subtypes with different clinical characteristics and functional impairments. We recruited 362 drug-naïve children with ADHD and 103 typically developing controls. The cluster analysis was used to identify subgroups based on the Child Behaviour Checklist (CBCL) and the Behaviour Rating Inventory of Executive Function (BRIEF). The subgroups' clinical characteristics and functional impairments were assessed using the WEISS Functional Impairment Rating Scale-Parent Report (WFIRS-P) and the Conners Parent Symptom Questionnaire (PSQ). The cluster analysis yielded four subgroups: (1) ADHD with severe impairment in psychopathology and executive functions (EF), (2) ADHD with mild executive dysfunctions and normal-level psychopathology, (3) ADHD with severe externalizing problems and (4) ADHD with severe executive dysfunctions. These subgroups showed different clinical characteristics and degrees of functional impairment. The EF impairment group displayed more serious learning problems and worse life skills than the externalizing group. The two groups with externalizing problems (i.e. the severe impairment group and the externalizing group) both exhibited higher rates of the combined subtype of ADHD and higher rates of comorbid ODD. Different subtypes of ADHD displayed different profiles of internalizing and externalizing problems and levels of executive dysfunctions. In particular, the subtype with severe impairment in EF exhibited more learning problems and worse life skills, suggesting EF is a critical target for intervention in children with ADHD.

Meta-analysis: Dose-Dependent Effects of Methylphenidate on Neurocognitive Functioning in Children With Attention-Deficit/Hyperactivity Disorder

OBJECTIVE

Neurocognitive deficits are at the heart of explanatory models of attention-deficit/hyperactivity disorder (ADHD), and lead to significant impairments in daily life. Determining the dosing effects of methylphenidate (MPH) on a broad range of neurocognitive functions and investigating possible impairing effects of high doses is therefore important.

METHOD

Placebo-controlled trials were included that investigated MPH dosing effects on neurocognitive functions in children and adolescents (aged 5-18 years) diagnosed with ADHD. Effect sizes (standardized mean differences [SMDs]) were calculated for different neurocognitive functions (baseline speed, variability in responding, nonexecutive memory and executive memory, inhibitory control, and cognitive flexibility) and, if available, for ADHD symptoms. Meta-regression analysis were used to investigate linear effects of dose (mg/kg/dose), and separate meta-analyses compared SMDs for 3 MPH dose ranges: low (0.10-0.30 mg/kg/dose), medium (0.31-0.60 mg/kg/dose), and high (0.61-1.00 mg/kg/dose).

RESULTS

A total of 31 studies fulfilled inclusion criteria, comprising 804 children with ADHD. Methylphenidate had beneficial effects on all neurocognitive functions (d = 0.20-0.73). Significant linear dosing effects were found for ADHD symptoms and lower-order neurocognitive functions (baseline speed, variability in responding, nonexecutive memory), with greater enhancement of functioning with increasing dose. No dosing effects were found for higher-order neurocognitive functions (executive memory, inhibitory control, and cognitive flexibility). No detrimental effects of MPH were found on any of the investigated functions.

CONCLUSION

Methylphenidate was superior to placebo in improving ADHD symptoms and a broad range of neurocognitive functions; however, effects sizes regarding the effects of dose vary substantially between functions. Our data highlight the importance of considering both neurocognitive and symptomatic aspects of ADHD in clinical practice.

Transdiagnostic symptom subtypes across autism spectrum disorders and attention deficit hyperactivity disorder: validated by measures of neurocognition and structural connectivity

BACKGROUNDS

Autism spectrum disorder (ASD) and attention-deficit hyperactivity disorder (ADHD) are neurodevelopmental disorders that exhibit within-disorder heterogeneity and cross-disorder phenotypic overlap, thus suggesting that the current disease categories may not fully represent the etiologic essence of the disorders, especially for highly comorbid neurodevelopmental disorders. In this study, we explored the subtypes of a combined sample of ASD and ADHD by integrating measurements of behavior, cognition and brain imaging.

METHODS

A total of 164 participants, including 65 with ASD, 47 with ADHD, and 52 controls, were recruited. Unsupervised machine learning with an agglomerative hierarchical clustering algorithm was used to identify transdiagnostic symptom clusters. Neurocognition and brain structural connectivity measurements were used to assess symptom clusters. Mediation analysis was used to explore the relationship between transdiagnostic symptoms, neurocognition and brain structural connectivity.

RESULTS

We identified three symptom clusters that did not fall within the diagnostic boundaries of DSM. External measurements from neurocognition and neuroimaging domains supported distinct profiles, including fine motor function, verbal fluency, and structural connectivity in the corpus callosum between these symptom clusters, highlighting possible biomarkers for ASD and ADHD. Additionally, fine motor function was shown to mediate the relationship between the corpus callosum and perseveration symptoms.

CONCLUSIONS

In this transdiagnostic study on ASD and ADHD, we identified three subtypes showing meaningful associations between symptoms, neurocognition and brain white matter structural connectivity. The fine motor function and structural connectivity of corpus callosum might be used as biomarkers for neurodevelopmental disorders with social skill symptoms. The results of this study highlighted the importance of precise phenotyping and further supported the effects of fine motor intervention on ASD and ADHD.

Facial emotion recognition impairment predicts social and emotional problems in children with (subthreshold) ADHD

Children with attention-deficit/hyperactivity disorder (ADHD) symptoms often experience social and emotional problems. Impaired facial emotion recognition has been suggested as a possible underlying mechanism, although impairments may depend on the type and intensity of emotions. We investigated facial emotion recognition in children with (subthreshold) ADHD and controls using a novel task with children's faces of emotional expressions varying in type and intensity. We further investigated associations between emotion recognition accuracy and social and emotional problems in the ADHD group. 83 children displaying ADHD symptoms and 30 controls (6-12 years) completed the Morphed Facial Emotion Recognition Task (MFERT). The MFERT assesses emotion recognition accuracy on four emotions using five expression intensity levels. Teachers and parents rated social and emotional problems on the Strengths and Difficulties Questionnaire. Repeated measures analysis of variance revealed that the ADHD group showed poorer emotion recognition accuracy compared to controls across emotions (small effect). The significant group by expression intensity interaction (small effect) showed that the increase in accuracy with increasing expression intensity was smaller in the ADHD group compared to controls. Multiple regression analyses within the ADHD group showed that emotion recognition accuracy was inversely related to social and emotional problems, but not prosocial behavior. Not only children with an ADHD diagnosis, but also children with subthreshold ADHD experience impairments in facial emotion recognition. This impairment is predictive for social and emotional problems, which may suggest that emotion recognition may contribute to the development of social and emotional problems in these children.

Longitudinal network model of the co-development of temperament, executive functioning, and psychopathology symptoms in youth with and without ADHD

Attention-deficit hyperactivity disorder (ADHD) is a common, chronic, and impairing disorder, yet presentations of ADHD and clinical course are highly heterogeneous. Despite substantial research efforts, both (a) the secondary co-occurrence of ADHD and complicating additional clinical problems and (b) the developmental pathways leading toward or away from recovery through adolescence remain poorly understood. Resolving these requires accounting for transactional influences of a large number of features across development. Here, we applied a longitudinal cross-lagged panel network model to a multimodal, multilevel dataset in a well-characterized sample of 488 children (nADHD = 296) to test Research Domain Criteria initiative-inspired hypotheses about transdiagnostic risk. Network features included Diagnostic and Statistical Manual of Mental Disorders symptoms, trait-based ratings of emotional functioning (temperament), and performance-based measures of cognition. Results confirmed that ADHD symptom domains, temperamental irritability, and working memory are independent transdiagnostic risk factors for psychopathology based on their direct associations with other features across time. ADHD symptoms and working memory each had direct, independent associations with depression. Results also demonstrated tightly linked co-development of ADHD symptoms and temperamental irritability, consistent with the possibility that this type of anger dysregulation is a core feature that is co-expressed as part of the ADHD phenotype for some children.

Toward a Revised Nosology for Attention-Deficit/Hyperactivity Disorder Heterogeneity

Attention-deficit/hyperactivity disorder (ADHD) is among the many syndromes in the psychiatric nosology for which etiological signal and clinical prediction are weak. Reducing phenotypic and mechanistic heterogeneity should be useful to arrive at stronger etiological and clinical prediction signals. We discuss key conceptual and methodological issues, highlighting the role of dimensional features aligned with Research Domain Criteria and cognitive, personality, and temperament theory as well as neurobiology. We describe several avenues of work in this area, utilizing different statistical, computational, and machine learning approaches to resolve heterogeneity in ADHD. We offer methodological and conceptual recommendations. Methodologically, we propose that an integrated approach utilizing theory and advanced computational logic to address targeted questions, with consideration of developmental context, can render the heterogeneity problem tractable for ADHD. Conceptually, we conclude that the field is on the cusp of justifying an emotionally dysregulated subprofile in ADHD that may be useful for clinical prediction and treatment testing. Cognitive profiles, while more nascent, may be useful for clinical prediction and treatment assignment in different ways depending on developmental stage. Targeting these psychological profiles for neurobiological and etiological study to capture different pathophysiological routes remains a near-term opportunity. Subtypes are likely to be multifactorial, cut across multiple dimensions, and depend on the research or clinical outcomes of interest for their ultimate selection. In this context parallel profiles based on cognition, emotion, and specific neural signatures appear to be on the horizon, each with somewhat different utilities. Efforts to integrate such cross-cutting profiles within a conceptual dysregulation framework are well underway.

The Course of Neurocognitive Functioning and Prediction of Behavioral Outcome of ADHD Affected and Unaffected Siblings

Longitudinal studies on the course of neurocognitive functioning of children with ADHD and their unaffected siblings are scarce. Also, it is unclear to what extent that course is related to ADHD outcomes. A carefully phenotyped large sample of 838 Caucasian participants (ADHD-combined type: n = 339, unaffected siblings: n = 271, controls: n = 228; mean age at baseline = 11.4 years, mean age at follow-up = 17.3 years, SD = 3.2) was used to investigate differences in the course of neurocognitive functioning of ADHD affected and unaffected siblings versus controls, and to investigate the relationship between neurocognitive change and ADHD outcomes. At baseline, an aggregated measure of overall neurocognitive functioning and eight neurocognitive measures of working memory, timing (speed/variability), motor control, and intelligence were investigated. Outcomes at follow-up were dimensional measures of ADHD symptom severity and the Kiddie-Global Assessment Scale (K-GAS) for overall functioning. At follow up, affected and unaffected siblings trended to, or fully caught up with performance levels of controls on four (44.4%) and five (55.6%) of the nine dependent variables, respectively. In contrast, performance in remaining key neurocognitive measures (i.e. verbal working memory, variability in responding) remained impaired at follow-up. Change in neurocognitive functioning was not related to ADHD outcomes. Our results question the etiological link between neurocognitive deficits and ADHD outcomes in adolescents and young adults.

Heterogeneity and Subtyping in Attention-Deficit/Hyperactivity Disorder-Considerations for Emerging Research Using Person-Centered Computational Approaches

Few if any experts believe that existing psychiatric diagnostic categories included in DSM and ICD are actually discrete disease entities. Attention-deficit/hyperactivity disorder (ADHD) is emblematic of the problems in the existing psychiatric classification system. ADHD symptoms reliably cluster into two correlated dimensions in factor analysis. However, children with ADHD vary considerably in their symptom profiles, symptom trajectories, clinical outcomes, and biological and psychological correlates. Thus, the field has sought alternative approaches that harness the dimensions of emotional, cognitive, and behavioral functioning that underlie ADHD and other existing psychiatric categories to create informative phenotypes that improve clinical prediction and clarify etiology. Within ADHD, cognitive (neuropsychological) and temperament/personality features have received considerable attention. In some cases, subphenotypes based on these features appear to improve on existing classifications and could eventually be translated into clinical practice. This review summarizes findings from subphenotyping efforts in ADHD that use cognitive, emotion-related, and other features to highlight major considerations for research applying person-oriented approaches to inform an improved psychiatric nosology. Considerations related to feature selection, validation of newly proposed divisions, defining populations of interest, and incorporating a developmental perspective are discussed.

Specific Effects of Individualized Cognitive Training in Children with Attention-Deficit/Hyperactivity Disorder (ADHD): The Role of Pre-Training Cognitive Impairment and Individual Training Performance

Objective: We investigated the impact of the pre-training neuropsychological (NP) impairment and of the training progress on the NP and behavioural outcome after computerized cognitive training (CogT) in children with ADHD. Method: Thirty-one participants underwent individualized CogT (focussing on one or two cognitive domains: working memory, inhibition, attention) over 12 weeks. NP tests and behaviour ratings served as outcome measures. Results: After CogT, significant improvements emerged according to parents' ratings, but only on very few NP test measures. Children with milder/no pre-training NP impairment showed larger improvements on behavioural ratings than more impaired children. A steeper training performance slope was related to better behavioural outcomes. Conclusion: We find partial support for specific effects of CogT, but the assumption that an individually tailored selection of training tasks would be particularly beneficial for children with ADHD with NP deficits was not confirmed. Trial registration number: NCT02358941.