Processing speed weakness in children and adolescents with non-hyperactive but inattentive ADHD (ADD)

Language and reading in attention-deficit/hyperactivity disorder and comorbid attention-deficit/hyperactivity disorder + developmental language disorder

Background

The current study sought to examine whether psycholinguistic assessments could discriminate children and adolescents with developmental language disorder (DLD) from those with attention-deficit/hyperactivity disorder (ADHD; combined or inattentive subtype) and comorbid DLD + ADHD.

Methods

The Clinical Evaluation of Language Fundamentals-Screening Test (CELFST; Wiig et al., 2013), the Comprehensive Test of Phonological Processing (nonword repetition subtest; Wagner et al., 2013), and the Test of Word Reading Efficiency (sight word and phonemic decoding subtests; Torgesen et al., 2012) were examined in 441 children and adolescents between 6 and 16 years of age.

Results

The presence of a language disorder (with or without ADHD) predicted poor performance across tasks. Children and adolescents with ADHD (combined vs. inattentive) only significantly differed in sight word reading, in favor of those with combined type. Measures of reading efficiency could distinguish between the two types of ADHD, but not between other groups. Interestingly, scores on the standard language screener were no worse for children with ADHD + DLD than children with DLD only.

Conclusions

The combination of comorbid ADHD + DLD did not appear to be associated with lower language abilities, sight word reading, or phonemic decoding relative to DLD alone. Reading efficiency was effective in discriminating between ADHD subtypes. These findings offer valuable insights into differential diagnosis and the identification of comorbidity.

Rhythmic Attention and ADHD: A Narrative and Systematic Review

In recent decades, a growing body of evidence has confirmed the existence of rhythmic fluctuations in attention, but the effect of inter-individual variations in these attentional rhythms has yet to be investigated. The aim of this review is to identify trends in the attention deficit/hyperactivity disorder (ADHD) literature that could be indicative of between-subject differences in rhythmic attention. A narrative review of the rhythmic attention and electrophysiological ADHD research literature was conducted, and the commonly-reported difference in slow-wave power between ADHD subjects and controls was found to have the most relevance to an understanding of rhythmic attention. A systematic review of the literature examining electrophysiological power differences in ADHD was then conducted to identify studies with conditions similar to those utilised in the rhythmic attention research literature. Fifteen relevant studies were identified and reviewed. The most consistent finding in the studies reviewed was for no spectral power differences between ADHD subjects and controls. However, the strongest trend in the studies reporting power differences was for higher power in the delta and theta frequency bands and lower power in the alpha band. In the context of rhythmic attention, this trend is suggestive of a slowing in the frequency and/or increase in the amplitude of the attentional oscillation in a subgroup of ADHD subjects. It is suggested that this characteristic electrophysiological modulation could be indicative of a global slowing of the attentional rhythm and/or an increase in the rhythmic recruitment of neurons in frontal attention networks in individuals with ADHD.

Attention deficit hyperactivity disorder: Neuropsychological profile and study of its impact on executive functions and academic performance

INTRODUCTION

The aim of the study was to describe the neuropsychological profile of patients with attention deficit hyperactivity disorder (ADHD) and the impact of the disorder on executive functioning and academic performance.

PATIENTS AND METHODS

We conducted a retrospective observational and analytical study. The sample consisted of 24 children with a diagnosis of ADHD (aged 6-15 years) without pharmacological treatment and 24 controls without ADHD (aged 7-15 years). A comprehensive neuropsychological evaluation was carried out, encompassing major cognitive domains, in addition to assessment of executive functioning and psychopathological symptoms through the administration of questionnaires to parents and teachers.

RESULTS

The cognitive profile of the ADHD group was characterized by overall scores (including executive functions and academic abilities) in the normal range (z scores between -1 and 1), although significantly lower compared to the control group. Over half of the patients with ADHD (58%) had associated specific learning disorders. Furthermore, teachers tended to report executive function difficulties more frequently in male students.

CONCLUSIONS

In the study sample, the group of patients with ADHD exhibited cognitive performance within the normal range, although with lower scores compared to controls. Behavioural rating scales provide valuable information about functioning outside the clinic, but may yield biased results on account of the focus on externalising symptoms. The neuropsychological evaluation is a useful tool that can facilitate the diagnosis of ADHD and an effective response to the needs and characteristics of patients and families.

Processing Speed Deficit and Its Relationship with Math Fluency in Children with Attention-Deficit/Hyperactivity Disorder

OBJECTIVES

(1) To determine the processing speed (PS) deficit in children with ADHD; and (2) To investigate if PS deficit was the primary cause of daily dysfunction in ADHD by testing the direct and indirect effects via working memory (WM) of PS on math fluency (MF).

METHOD

Seventy-eight children (52 children with ADHD and 26 controls) were tested on their motor, perceptual, cognitive, and verbal PS, WM, and MF.

RESULTS

Children with ADHD performed worse than controls on all PS, suggesting a general PS deficit. Moreover, cognitive PS was a significant predictor for MF. Mediation analysis showed that cognitive PS had direct and indirect effects via WM on MF, suggesting PS deficit might be the primary cause of MF difficulties in ADHD.

CONCLUSION

Findings of this study suggested a general PS deficit in ADHD. Due to the importance of PS in MF, interventions for MF underachievers should include assessment and training of PS.

Developmental Correlates of Accelerated Molar Eruption in Early Childhood

Background

Adversity has been linked to accelerated maturation. Molar eruption is a simple and scalable way to identify early maturation, but its developmental correlates remain unexplored. Thus, we examined whether accelerated maturation as indexed by molar eruption is associated with children's mental health or cognitive skills.

Methods

Molar eruption was evaluated from T2-weighted magnetic resonance imaging in 117 children (63 female; ages 4-7 years). Parents reported on child mental health with the Child Behavior Checklist. Children completed standardized assessments of fluid reasoning, working memory, processing speed, crystallized knowledge, and math performance. Relationships between molar eruption and developmental outcomes were examined using linear models, with age, gender, and stress risk as covariates.

Results

Earlier molar eruption was positively associated with children's externalizing symptoms (false discovery rate-corrected p [pFDR] = .027) but not internalizing symptoms, and the relationship with externalizing symptoms did not hold when controlling for stress risk. Earlier molar eruption was negatively associated with fluid reasoning (pFDR < .001), working memory (pFDR = .033), and crystallized knowledge (pFDR = .001). The association between molar eruption and both reasoning and crystallized knowledge held when controlling for stress risk. Molar eruption also partially mediated associations between stress risk and both reasoning (proportion mediated = 0.273, p = .004) and crystallized knowledge (proportion mediated = 0.126, p = .016).

Conclusions

Accelerated maturation, as reflected in early molar eruption, may have consequences for cognitive development, perhaps because it constrains brain plasticity. Knowing the pace of a child's maturation may provide insight into the impact of a child's stress history on their cognitive development.

Timing and delay discounting in attention-deficit/hyperactivity disorder: A translational approach

Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder that often presents with abnormal time perception and increased impulsive choice behavior. The spontaneously hypertensive rat (SHR) is the most widely used preclinical model of the ADHD-Combined and ADHD-Hyperactive/Impulsive subtypes of the disorder. However, when testing the spontaneously hypertensive rat from Charles River (SHR/NCrl) on timing and impulsive choice tasks, the appropriate control strain is not clear, and it is possible that one of the possible control strains, the Wistar Kyoto from Charles River (WKY/NCrl), is an appropriate model for ADHD-Predominately Inattentive. Our goals were to test the SHR/NCrl, WKY/NCrl, and Wistar (WI; the progenitor strain for the SHR/NCrl and WKY/NCrl) strains on time perception and impulsive choice tasks to assess the validity of SHR/NCrl and WKY/NCrl as models of ADHD, and the validity of the WI strain as a control. We also sought to assess impulsive choice behavior in humans diagnosed with the three subtypes of ADHD and compare them with our findings from the preclinical models. We found SHR/NCrl rats timed faster and were more impulsive than WKY/NCrl and WI rats, and human participants diagnosed with ADHD were more impulsive compared to controls, but there were no differences between the three ADHD subtypes.

Acute effects of concussion among adolescents with attention-deficit/hyperactivity disorder

Adolescents with ADHD have a greater lifetime history of concussion and experience concussion-like symptoms in the absence of a concussion, complicating concussion assessment and management. It is well established that individuals who experience greater acute symptoms following concussion are at risk for slower recovery and persistent symptoms. We examined whether youth with ADHD experience worse acute effects, within the first 72 h following concussion, compared to youth without ADHD. We hypothesized that youth with ADHD would perform worse on neurocognitive testing and endorse more severe symptoms acutely following injury, but the magnitude of change from pre injury to post injury would be similar for both groups, and thus comparable to baseline group differences. The sample included 852 adolescents with pre-injury and post-injury ImPACT results (within 72 h); we also conducted supplementary case-control analyses on a subset of youth with and without ADHD matched on demographics and pre-injury health history. For both samples, there were significant interaction effects for the Verbal Memory and Visual Motor Speed composites (p < 0.01, η²=.01-.07, small-medium effect), such that youth with ADHD showed a greater magnitude of diminished cognitive functioning from pre-injury to post-injury testing. There were no significant differences in the magnitudes of changes from pre injury to post injury with regard to overall symptom reporting (i.e., total symptom severity scores, total number of symptoms endorsed); however, there were group differences in endorsement rates for several individual symptoms. Further research is needed to determine whether such differential acute effects are associated with recovery time in youth with ADHD.

Is Processing Speed (Gs) related to Hyperactivity (As a Narrow Cognitive Area of Gps): A Dimensional Approach to Heterogeneity of Clinical and WISC-IV Cognitive Profiles in ADHD From RDoC/HiTOP Perspective

OBJECTIVE

The aim of this study was to investigate the relationship between symptomatology and the Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV) cognitive profiles in Attention Deficit and Hyperactivity Disorder (ADHD), taking into account clinical heterogeneity.

METHOD

The WISC-IV was administered to 60 children aged 6 to 13 years with ADHD who had not previously taken psychotropic medication. Conners Teacher-Rating Scale (CTRS-R/L) and Conners Parent-Rating Scale (CPRS-R/L) were completed by parents and teachers.

RESULTS

We found a statistically significant positive correlation between the symptoms of hyperactivity/impulsivity and PSI (Processing Speed Index). A statistically significant negative correlation was found between the CTRS-R/L's DSM-IV Inattentive subscale and PRI (Perceptual Reasoning Index). No relationship was found between the inattention or hyperactivity/impulsivity symptomatology with Working Memory Index (WMI). WMI stood out as the most frequently reported weakness among the four index scores.

CONCLUSION

Considering the relationship between the cognitive domains of RDoC (Research Domain Criteria) and dimensions of HiTOP with the ADHD symptom clusters, the assessment of cognitive and behavioral symptoms may be useful for phenotyping ADHD. According to the CHC (Cattell-Horn-Carroll) theory; the positive correlation level between PSI, which is accepted as Gs, and hyperactivity/impulsivity symptoms in people with ADHD may be due to the fact that hyperactivity is one of the narrow cognitive domains of Gps.

Cognitive and Executive Contributions to Trail-Making Task Performance on Adolescents With and Without Attention Deficit Hyperactivity Disorder

OBJECTIVE

The trail making task is used to assess executive functioning in ADHD youth, yet has only been validated in adult populations. We compare the relative contributions of various cognitive measures to performance on a trail making task analog, the Switching of Attention (SoA) task, in typically-developing and ADHD adolescents.

METHOD

Participants were 160 adolescents with ADHD from the International Study to Predict Optimized Treatment-in ADHD, assessed at pretreatment baseline and 6-week medicated follow-up, and 160 matched typically-developing peers. Attention, processing speed, working memory, impulsivity, and motor speed were assessed using a cognitive battery.

RESULTS

Processing speed and working memory significantly contributed to SoA performance in ADHD, regardless of medication status. While medicated, motor speed also underpinned the prediction of most task measures. For typically-developing adolescents, sustained attention and working memory contributed to SoA performance.

CONCLUSION

Typically-developing, unmedicated and treated ADHD adolescents recruit different aspects of cognition during SoA completion.

Longitudinal Temperament Pathways to ADHD Between Childhood and Adolescence

The current investigation extended prior cross-sectional mapping of etiological factors, transdiagnostic effortful and affective traits, and ADHD symptoms to longitudinal pathways extending from two etiological domains: polygenic and prenatal risk. Hypotheses were (1) genetic risk for ADHD would be related to inattentive ADHD symptoms in adolescence and mediated by childhood effortful control; (2) prenatal smoking would be related to hyperactive-impulsive ADHD symptoms during childhood and mediated by childhood surgency; and (3) there would be age-related variation, such that mediation of genetic risk would be larger for older than younger ages, whereas mediation of prenatal risk would be larger in earlier childhood than at later ages. Participants were 849 children drawn from the Oregon ADHD-1000 Cohort, which used a case control sample and an accelerated longitudinal design to track development from childhood (at year 1 ages 7-13) through adolescence (at year 6 ages 13-19). Results showed the mediational pathway from prenatal smoking through surgency to hyperactivity-impulsivity at Year 1 was significant (indirect effect estimate = .053, p < .01). The mediational pathway from polygenic risk through effortful control to inattention at Year 6 was also significant (indirect effect estimate = .084, p < .01). Both results were independent of the association between inattention and hyperactivity-impulsivity and control for the alternative etiological input and held across parent- and teacher-report of ADHD symptoms. In line with dual pathway models of ADHD, early prenatal risk for hyperactivity-impulsivity appears to operate through surgency, while polygenic genetic risk for inattention appears mediated by effortful control.

What is a processing speed weakness? Importance of cognitive ability when defining processing speed in a child psychiatric population

There is growing evidence that processing speed (PS) deficits in youth with neuropsychiatric conditions are associated with functional difficulties. However, there is no consistent definition of slower PS; specifically, whether slower PS should be defined as a discrepancy from same-aged peers (normative weakness) or as an intrapersonal deficit relative to overall cognitive ability (relative weakness). In a sample of clinically-referred youth, we calculated slower PS both ways and examined the impact on adaptive, academic, and psychopathology outcomes in relation to different levels of cognitive ability. Significant PS x cognitive ability interactions were found on adaptive and academic outcomes. A norm-based weakness in PS (PSI Standard Score <85) was associated with lower adaptive skills and lower academic skills regardless of cognitive ability. In the above average cognitive ability group, relatively lower PS (PSI >15 point difference from VCI) was associated with significantly lower academic performance. No significant associations were found for general psychopathology. Results suggest a normative weakness in PS impacts functional outcomes interactively and differently with level of general cognitive ability. Data suggest that higher cognitive ability may be somewhat protective from the impact of normatively weak PS on adaptive outcomes; however, youth across all abilities with normatively weak PS showed weaker academic performance. Second, children with high cognitive abilities and relatively weak PS showed discrepant performance compared to comparison group. Implications and areas for future research are discussed.

The relationship between cognition and mathematics in children with attention-deficit/hyperactivity disorder: a systematic review

Cognitive processes play an imperative role in children's mathematics learning. Difficulties in cognitive functioning are a core feature of Attention Deficit Hyperactivity Disorder (ADHD) in children, who also tend to show lower levels of mathematics attainment than their typically developing peers. This review (registration number: CRD42020169708) sought to aggregate findings from studies assessing the relationship between cognition and mathematics in children with a clinical ADHD diagnosis aged 4-12 years. A total of 11,799 studies published between 1992 and August 2020 were screened for eligibility using various database (PsycINFO, PubMed, SCOPUS, EMBASE, ERIC, Web of Science, and additional sources), from which four studies met inclusion criteria. A narrative synthesis was conducted on the correlations between mathematics and cognitive domains, including an evaluation of the risk of bias within the studies. Across four studies meeting inclusion criteria, memory, inhibitory control, and processing speed were assessed. The results showed a positive association between cognition and mathematics performance in this population. The strength of associations across these studies varied as a function of the cognitive domain in question, means by which mathematics performance was assessed, as well as whether confounding factors such as age and IQ were controlled for. Collectively, this review demonstrates a lack of research in this area and points to various methodological considerations for identifying the association between cognition and mathematics performance in ADHD.

Basic and complex cognitive functions in Adult ADHD

Background

Many clinical studies reported deficits in basic and complex cognitive functions in adults with Attention-Deficit/Hyperactivity Disorder (ADHD). However, the extent in which deficits in basic functions (i.e., processing speed and distractibility) contribute to complex cognitive impairments (i.e., working memory, planning, cognitive flexibility, memory functions) in adults with ADHD is not well-studied. So far, literature show only one study, revealing that basic functions explain 27–74% of executive dysfunctions. Yet, the authors reported that findings could be affected by the selection of neuropsychological tests. The goal of the present research is to replicate such a finding using a different sample and a different set of neuropsychological tests.

Methods

Forty-eight adult patients with ADHD were compared with 48 healthy controls in basic cognitive functions, namely processing speed and distractibility and more complex cognitive functions, namely selective attention, cognitive flexibility, planning, working memory, verbal fluency, and verbal memory. Basic and complex cognitive functions were assessed using the Vigilance and Sustained Attention, Selective Attention, N-Back, Tower of London, Trail Making Test, Word Fluency, and Verbal Learning and Memory.

Results and conclusion

Logistic regression analyses showed that impairments in complex cognitive functions explained 25% of the variance in ADHD diagnosis. The explained variance dropped from 25% to 9% after considering basic functions of processing speed and distractibility. This 64% reduction highlights the importance of basic functions for impairments in complex functions in patients with ADHD.

Time Perception is a Focal Symptom of Attention-Deficit/Hyperactivity Disorder in Adults

Attention-Deficit/Hyperactivity Disorder (ADHD) is classically associated with symptoms that include inattentiveness, hyperactivity, and impulsivity together with a variety of other observable externalized symptoms. ADHD has also been associated with specific internalized cognitive symptoms, including restlessness and emotional impulsivity. This disorder has been recognized as a lifelong condition and can be recognized by a variety of unique cognitive phenomena. In addition to the frequently ignored affective symptoms exhibited by individuals diagnosed with ADHD, problems with time perception have been noted, although these are considered to be secondary issues. Temporal shifts in cognitive processing, however, may be at the very root of ADHD-related symptoms, given the importance of coordinated signal translation in the construction of behavior. In this review, we consider the evidence that suggests that differences in time perception are a central symptom in adults with ADHD. Some of these differences include the feeling of time moving faster, which causes difficulties in prospective time tasks and inaccuracies in time estimation tasks. We analyze the literature from both neurological and psychological perspectives and include an assessment of tools that can be administered via computer to measure time perception. We also suggest several computer-based methods that might be used to address problems with time perception in both children and adults. We strongly recommend the inclusion of ADHD symptoms associated with time perception in the next revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM) published by the American Psychiatric Association.

Clinical presentations of attention-deficit/hyperactivity disorder (ADHD) in children and adolescents: comparison of neurocognitive performance

This study aimed to compare performance in working memory (WM), processing speed (PRS), and attention measures in children and adolescents with typical development (TD) and with Attention deficit hyperactivity disorder (inattentive [ADHD-I] or combined [ADHD-C]) presentations, and to determine the predictive ability of the measures mentioned to discriminate between ADHD presentations and TD. 260 children and adolescents, 138 with ADHD (70 ADHD-I and 68 ADHD-C) and 122 TD in two age cohorts (8-12 years; 13-16 years), were assessed with WM and PRS indexes of Wechsler Intelligence Scale for Children (WISC-IV) and the d2 attention test. Significant differences between ADHD and TD groups in the WISC-IV GAI scores were found in children but not in adolescents. Children and adolescents with both ADHD presentations performed poorly on the PRS index, while on the WM index only children exhibited difficulties. In the attention test, children with ADHD-C showed more impulsivity and more difficulties for processing speed, concentration and accuracy than ADHD-I and TD. In addition, both ADHD presentations had higher inattention scores than TD. ADHD adolescents performed worse than TD in processing speed, concentration and accuracy. ADHD groups showed more impulsivity and inattention than TD. Digit Span and Symbol Search (WISC-IV) and processing speed and accuracy (d2) successfully classified ADHD and TD in children, but in adolescents, only coding (WISC-IV) and accuracy (d2) successfully classified ADHD presentations and TD. The WISC-IV and d2 yield neuropsychological profiles which reflect age-related cognitive changes and may allow the adaptation of more tailored early interventions for ADHD.

Psychiatric Comorbidity in the Subtypes of ADHD in Children and Adolescents with ADHD According to DSM-IV

Introduction

The prevalence rate of psychiatric comorbidity in children and adolescents with Attention Deficit Hyperactivity Disorder (ADHD) was 60-80%. The objective of this study was to examine comorbid disorders associated with ADHD and the subtypes of ADHD in children and adolescents with the diagnosis of ADHD.

Method

The study included 326 children and adolescents aged between 8-15 years who were diagnosed with ADHD for the first time as a result of an interview by psychiatry, in a child adolescent psychiatry clinic in İzmir. Sociodemographic form, Turgay DSM-IV Disruptive Behavior Disorders Rating Scale and Kiddie Schedule for Affective Disorders and Schizophrenia for School-Age Children Present and Lifetime version were used to assess psychiatric comorbidity.

Results

The comorbidities accompanied ADHD were disruptive behavior disorder (28.8%), depressive disorder (13.2%), obsessive-compulsive disorder (9.5%) and anxiety disorder (6.1%). When the subtypes of ADHD were assessed according to psychiatric comorbidity, oppositional defiant disorder and conduct disorder were frequently seen with ADHD combined type, whereas anxiety disorder was more frequent with ADHD inattentive type.

Discussion

Comorbidity in ADHD Combined type increases the severity of disease, delays treatment response and exacerbates prognosis. Therefore, it is very important to determine which psychiatric diagnosis accompany with ADHD.

Attention-Deficit/Hyperactivity Disorder Predominantly Inattentive Subtype/Presentation: Research Progress and Translational Studies

Research on the predominantly inattentive attention-deficit/hyperactivity disorder (ADHD-PI) subtype/presentation is important given its high prevalence, but paradoxically it is under-recognized and undertreated. The temporal stability of the inattention symptom could impact the high worldwide prevalence of ADHD-PI. Some evidence suggests differences in the nature of attentional deficit in ADHD-PI vs. that in other subtypes. Impairments in neuropsychological, neurocognitive, and social functioning are also evident in ADHD-PI, which could be specific to the subtype (e.g., processing speed, social perception, and skills), or differ from others in severity. Neuroimaging studies have also revealed ADHD-PI-specific neuropathological abnormalities and those that are shared with other subtypes. ADHD-PI is highly comorbid with learning and internalizing (e.g., anxiety and depression) disorders. There is no solid evidence for ADHD-PI-specific genetic etiologies and differential responses of subtypes to ADHD medications. Translational studies have used the Wistar Kyoto/NCrl substrain which requires further characterizations as an ADHD-PI model. Overall, ADHD-PI research has been conducted in the context of the Diagnostic and Statistical Manual, which arguably does not conform to the widely recognized "dimensional" view of ADHD. The Research Domain Criteria has been proposed to provide a novel framework for understanding the nature of neuropsychiatric illnesses and ultimately improve their diagnosis and treatment.

Using virtual reality to define the mechanisms linking symptoms with cognitive deficits in attention deficit hyperactivity disorder

The mechanisms underpinning attentional deficits are only partially understood. Here we ask if shifts in a child's field of view (FOV) act as a mediator between symptoms of attention deficit hyperactivity disorder (ADHD) and associated cognitive anomalies, particularly in attentional processes. Real time measurement of shifts in FOV were obtained on 85 children (mean age 9.4 (SD 1.9) years; 45 with DSM 5-defined ADHD) as they completed the continuous performance task in a "virtual classroom". We extracted measures reflecting focused and selective attention across the task, along with diffusion modelling of latent cognitive processes of information uptake, response conservativeness and non-decision time. Mediation analyses showed that shifts in FOV partially mediated the relationship between hyperactive impulsive symptoms and both poor focused attention and information uptake. Performance accuracy decreased and shifts in FOV increased during the task, but these changes over time did not differ by symptom severity. Employing virtual reality and mediation analysis, we implicate shifts in FOV as a mechanism linking symptoms of ADHD and deficits in focused attention and in the gathering of information to make decisions. The identification of mediating mechanisms might provide new targets for intervention.

Slow Processing Speed and Sluggish Cognitive Tempo in Pediatric Attention-Deficit/Hyperactivity Disorder: Evidence for Differentiation of Functional Correlates

The association between slow processing speed and sluggish cognitive tempo (SCT), a phenotype described within attention-deficit/hyperactivity disorder (ADHD) samples over the past decade, remains unclear. We examined whether SCT and processing speed predict different functional correlates within children and adolescents with ADHD. Participants were 193 clinically-referred youth meeting DSM ADHD criteria without comorbid conditions (mean age = 9.9 years, SD = 2.5; age range 6-16). The incremental utility of SCT and processing speed to predict (1) adaptive functioning and (2) academic achievement, after controlling for age, sex, medication status, and ADHD symptom burden, was assessed using hierarchical multiple regressions. SCT symptoms significantly predicted adaptive functioning, accounting for 6% of the variance, but did not predict academic achievement. Processing speed did not add incrementally to the prediction of adaptive functioning, but did predict academic achievement, accounting for 4% of the variance. Results suggest that SCT and processing speed differentially predict functional abilities not accounted for by ADHD symptom burden.

Error-Related Dynamics of Reaction Time and Frontal Midline Theta Activity in Attention Deficit Hyperactivity Disorder (ADHD) During a Subliminal Motor Priming Task

Post-error slowing (PES) is an established performance monitoring readout. Several previous studies have found that PES is reduced in children and adolescents with attention-deficit hyperactivity disorder (ADHD). We analyzed reaction time data, along with electroencephalography (EEG) data, from a response priming experiment in children and adolescents with ADHD (N = 28) and typically developing (TD) controls (N = 15) between 10 and 17 years of age. We report dynamic reaction time changes before and after errors: whereas TD controls readjusted their response speed to their individual average speed after committing an error, this reaction time adjustment appeared to be delayed and decreased in ADHD patients. In the EEG, error trials were accompanied by increased frontal midline theta activity, which was attenuated in ADHD compared to TD. We conclude that PES has a different time course rather than being fully absent in ADHD and discuss relationships with our EEG findings and potential implications for performance monitoring in ADHD.

Which components of processing speed are affected in ADHD subtypes?

The term "processing speed" (PS) encompasses many components including perceptual, cognitive and output speed. Despite evidence for reduced PS in Attention-Deficit/Hyperactivity Disorder (ADHD), little is known about which component(s) is most impacted in ADHD, or how it may vary by subtypes. Participants included 151 children, ages 8-12 years, with ADHD Predominantly Inattentive Type, ADHD Combined Type and typically developing controls using DSM-IV criteria. All children completed four measures of processing speed: Symbol Search, Coding, Decision Speed, and simple reaction time. We found children with ADHD-PI and ADHD-C had slower perceptual and psychomotor/incidental learning speed than controls and that ADHD-PI had slower decision speed than controls. The subtypes did not differ on any of these measures. Mean reaction time was intact in ADHD. Hence, at a very basic output level, children with ADHD do not have impaired speed overall, but as task demands increase their processing speed becomes less efficient than controls'. Further, perceptual and psychomotor speed were related to inattention, and psychomotor speed/incidental learning was related to hyperactivity/impulsivity. Thus, inattention may contribute to less efficient performance and worse attention to detail on tasks with a higher perceptual and/or psychomotor load; whereas hyperactivity/impulsivity may affect psychomotor speed/incidental learning, possibly via greater inaccuracy and/or reduced learning efficiency. Decision speed was not related to either dimension. Results suggest that PS deficits are primarily linked to the inattention dimension of ADHD but not exclusively. Findings also suggest PS is not a singular process but rather a multifaceted system that is differentially impacted in ADHD.

Clinical Implications of the Perception of Time in Attention Deficit Hyperactivity Disorder (ADHD): A Review

Attention deficit hyperactivity disorder (ADHD) is a lifelong neurodevelopmental disorder that can affect many areas of the daily life of individuals and is associated with poor health outcomes and with debilitating deficits in executive function. Recently, increasing numbers of research studies have begun to investigate the associations between neural and behavioral manifestations of ADHD. This review summarizes recent research on the perception of time in ADHD and proposes that this symptom is a possible diagnostic characteristic. Controlled studies on time perception have compared individuals with ADHD with typically developing controls (TDCs) and have used methods that include the Zimbardo Time Perspective Inventory (ZTPI). Practical approaches to time perception and its evaluation have shown that individuals with ADHD have difficulties in time estimation and discrimination activities as well as having the feeling that time is passing by without them being able to complete tasks accurately and well. Although ADHD has been associated with neurologic abnormalities in the mesolimbic and dopaminergic systems, recent studies have found that when individuals with ADHD are treated medically, their perception of time tends to normalize. The relationship between ADHD and the perception of time requires greater attention. Further studies on time perception in ADHD with other abnormalities, including executive function, might be approaches that refine the classification and diagnosis of ADHD and should include studies on its varied presentation in different age groups.

Zum Zusammenhang von Arbeitsgedächtnisleistungen und ausgewählten Exekutivfunktionen bei Kindern mit ADHS

Zusammenfassung. Defizite in Exekutivfunktionen werden als ein wesentliches Merkmal einer Aufmerksamkeitsdefizit-/Hyperaktivitätsstörung angesehen. Bisher liegen wenige standardisierte Testverfahren zur Erfassung solcher exekutiven Defizite vor, die bei Kindern und Jugendlichen besonders eng mit einer ADHS assoziiert scheinen (kognitive Flexibilität, Inhibition, Handlungsplanung, „Switching“). Das Hauptziel der vorliegenden Studie war deshalb die Validierung des neuropsychologischen Moduls des ADHS-Diagnostikums für Kinder und Jugendliche (ADHS-KJ-NPT). Diesbezüglich wurde eine Stichprobe von 58 ADHS-Kindern (77.6 % männlich) im Alter von 6 bis 12 Jahren ( M = 9.01 Jahre; SD = 1.43) mit dem ADHS-KJ-NPT sowie mit den Untertests des Index Arbeitsgedächtnis und des Index Verarbeitungsgeschwindigkeit des Wechsler-Intelligenztests (WISC-V) untersucht. Die Ergebnisse zeigen, dass die ADHS-KJ-NPT-Untertests, die darauf abzielen, Defizite in der Inhibitionsfähigkeit zu erfassen, mit dem WISC-V-Index Arbeitsgedächtnis korrelieren. Zudem wurden Korrelationen zwischen dem WISC-V-Index Verarbeitungsgeschwindigkeit und den ADHS-KJ-NPT-Untertests gefunden, mit denen Defizite in der flexiblen Aufmerksamkeitssteuerung und in der Inhibitionsfähigkeit auf äußere Reize erfasst werden sollen. Diese Korrelationen stellten sich bei 6- bis 9-jährigen Kindern als substanziell heraus, während dies bei 10- bis 12-Jährigen nicht der Fall ist. Die Studie trägt weiter zur Fundierung der Kriteriumsvalidität des neuropsychologischen Moduls des ADHS-KJ bei.

The Role of Information Processing Speed in Clinical and Social Support Variables of Patients with Multiple Sclerosis

BACKGROUND AND PURPOSE

Information processing speed is one of the most impaired cognitive functions in multiple sclerosis (MS). There are two tests widely used for evaluating information processing speed: the Symbol Digit Modalities Test (SDMT) and the Paced Auditory Serial Addition Test (PASAT). To analyze the relationship between processing speed and the clinical and social support variables of patients with MS.

METHODS

A group of 47 patients with relapsing-remitting MS was studied, 31 were women and 16, men. Age: 39.04±13.17, years of schooling: 13.00±3.87, Expanded Disability Status Scale (EDSS): 2.78±1.81, and disease evolution: 8.07±6.26. Instruments of measure; processing speed: SDMT, PASAT, clinical variables: EDSS, Fatigue Severity Scale (FSS), Beck's Depression Inventory II (BDI-II), and social support: Medical Outcomes Study Social Support Survey (MOS).

RESULTS

Significant correlations were found between information processing speed and psychiatric, motor disability and social support variables. The SDMT correlated significantly and negatively with BDI-II, FSS, EDSS, and MOS (p<0.05), whereas the PASAT correlated negatively with FSS and positively with MOS (p<0.05). Information processing speed appeared as the performance predictor of these variables. The SDMT produced significant changes in EDSS (R²=0.343, p=0.000); FSS (R²=0.109, p=0.031); BDI-II (R²=0.124, p=0.018), and MOS (R²=between 0.212 and 0.379, p<0.05).

CONCLUSIONS

Information processing speed has influence on the clinical variables and the social support of patients with MS. These aspects are important to bear in mind for therapeutic approach.

A Double Dissociation Between Inattentive and Impulsive Traits, on Tasks of Visual Processing and Emotion Regulation

OBJECTIVE

To dissociate between inattentive and impulsive traits common in attention deficit hyperactivity disorder (ADHD) using a non-dichotomous measurment of these traits.

METHOD

120 university students who completed the Conner's adult ADHD rating scales (CAARS) were also tested on the Microgenesis task which requires visual attention and on the Cyber Cruiser task which requires emotion regulation.

RESULTS

Results show that a measure of inattention was specifically related to a measure of effortful visual processing condition. In addition, a measure of impulsivity was specifically related to the tendency to fail in refueling one's car on time, although this relation was opposite to the predicted direction. Furthermore, by using exploratory and confirmatory factor analyses, the CAARS' factor structure was confirmed to be relevant to an Israeli population.

CONCLUSION

The current experiment supports the idea that visual attention may play a part in inattentive symptoms, and that emotion regulation may play a part in impulsivity symptoms.

Clinical and functional correlates of processing speed in pediatric Attention-Deficit/Hyperactivity Disorder: a systematic review and meta-analysis

It is well established that processing speed is negatively impacted in children and adolescents with Attention-Deficit/Hyperactivity Disorder (ADHD). Unfortunately, exactly how processing speed vulnerabilities manifest in daily functioning has not been well established. To support clinical care of youth with ADHD, it is important to better understand the functional consequences and relevant outcomes associated with processing speed deficits. This systematic review and meta-analysis sought to identify the association between processing speed and clinical or functional correlates among children or adolescents diagnosed with ADHD. A total of 409 abstracts were screened, of which, 60 full-text articles were identified as potentially relevant, and 8 of these studies met inclusion criteria. Domains evaluated across these studies included reading skills, mathematics skills, written expression, anxiety, self-appraisals of competence, and adaptive functioning. Six studies reported an association between processing speed and reading skills, allowing for meta-analysis. Processing speed difficulties among youth with ADHD appear strongly associated with several clinical and functional correlates including weaker academic skills, poorer adaptive skills, increased self-reported anxiety, and overestimates of social competence. Meta-analytic results for studies reporting the association between processing speed and reading skills indicate a medium overall weighted mean effect size (r = 0.33, 95% CI = 0.28 -0.39) with minimal heterogeneity (I² = 0.17). Clinical implications of these findings, limitations in the current knowledge base, and suggestions for future research are discussed.

Unique white matter microstructural patterns in ADHD presentations-a diffusion tensor imaging study

Attention-deficit/hyperactivity disorder predominantly inattentive (ADHD-PI) and combined (ADHD-C) presentations are likely distinct disorders that differ neuroanatomically, neurochemically, and neuropsychologically. However, to date, little is known about specific white matter (WM) regions differentiating ADHD presentations. This study examined differences in WM microstructure using diffusion tensor imaging (DTI) data from 20 ADHD-PI, 18 ADHD-C, and 27 typically developed children. Voxel-wise analysis of DTI measurements in major fiber bundles was carried out using tract-based spatial statistics (TBSS). Clusters showing diffusivity abnormalities were used as regions of interest for regression analysis between fractional anisotropy (FA) and neuropsychological outcomes. Compared to neurotypicals, ADHD-PI children showed higher FA in the anterior thalamic radiations (ATR), bilateral inferior longitudinal fasciculus (ILF), and in the left corticospinal tract (CST). In contrast, the ADHD-C group exhibited higher FA in the bilateral cingulum bundle (CB). In the ADHD-PI group, differences in FA in the left ILF and ATR were accompanied by axial diffusivity (AD) abnormalities. In addition, the ADHD-PI group exhibited atypical mean diffusivity in the forceps minor (FMi) and left ATR and AD differences in right CB compared to healthy subjects. Direct comparison between ADHD presentations demonstrated radial diffusivity differences in FMi. WM clusters with FA irregularities in ADHD were associated with neurobehavioral performance across groups. In conclusion, differences in WM microstructure in ADHD presentations strengthen the theory that ADHD-PI and ADHD-C are two distinct disorders. Regions with WM irregularity seen in both ADHD presentations might serve as predictors of executive and behavioral functioning across groups. Hum Brain Mapp 37:3323-3336, 2016. © 2016 Wiley Periodicals, Inc.

Decreasing ADHD phenotypic heterogeneity: searching for neurobiological underpinnings of the restrictive inattentive phenotype

During the process of developing the DSM-5, a new phenotype of ADHD was proposed-the ADHD restrictive inattentive presentation (ADHD-RI), describing subjects with high endorsement of inattentive symptoms and a low level of hyperactivity. However, this phenotype was not included in the DSM-5 because of the lack of robust neurobiological data. We aimed to assess the specific neurobiological underpinnings of individuals presenting ADHD-RI. We compared a sample of 301 subjects (101 ADHD-Combined; 50 ADHD-RI; 50 ADHD predominantly inattentive type and 100 typically developing subjects) aged 8-15 years, using a complete neuropsychological battery, molecular genetic data (DRD4 and DAT1 most studied polymorphisms) and functional MRI during a Go-No/Go task. Subjects with ADHD-RI had a significantly different neuropsychological profile compared with the other groups, including lower psychomotor speeds, longer reaction times and the worst overall performance in the global neurocognitive index. The proportion of subjects with the presence of DRD4-7 repeat allele was significantly higher in ADHD-RI. The fMRI data suggested that more attention-related posterior brain regions (especially temporo-occipital areas) are activated in ADHD-RI during both Go and No-Go cues compared to TD controls and ADHD predominantly inattentive type. ADHD-RI may represent a different phenotype than other types of ADHD. In addition, our results suggest that reducing the phenotypic heterogeneity may aid in the search for the neurobiological underpinnings of ADHD.

Dispositional Trait Types of ADHD in Young Children

OBJECTIVE

This study evaluated a novel person-centered approach to parsing ADHD heterogeneity using dispositional traits.

METHOD

Participants were one hundred nine 3- to 6-year-olds, and their primary caregivers and day care providers/teachers who completed a multi-informant diagnostic procedure with longitudinal follow-up.

RESULTS

Based on latent profile analysis, young children with ADHD could be divided into low control, high surgency, and high negative affect subgroups. The low control and high surgency groups exhibited increased parent- and teacher-rated hyperactive-impulsive and oppositional-defiant disorder (ODD) symptoms. Although the low control group exhibited the worst response inhibition, the high surgency group exhibited the worst working memory. Furthermore, the high surgency group exhibited high aggression and increasing levels of hyperactivity-impulsivity and ODD symptoms over time.

CONCLUSION

A subgroup of young children with ADHD with high surgency may be at particular risk for comorbid psychopathology and longitudinal worsening of symptoms.

Rapid Automatized Naming in Children with Dyslexia: Is Inhibitory Control Involved?

Rapid automatized naming (RAN) is widely seen as an important indicator of dyslexia. The nature of the cognitive processes involved in rapid naming is however still a topic of controversy. We hypothesized that in addition to the involvement of phonological processes and processing speed, RAN is a function of inhibition processes, in particular of interference control. A total 86 children with dyslexia and 31 normal readers were recruited. Our results revealed that in addition to phonological processing and processing speed, interference control predicts rapid naming in dyslexia, but in contrast to these other two cognitive processes, inhibition is not significantly associated with their reading and spelling skills. After variance in reading and spelling associated with processing speed, interference control and phonological processing was partialled out, naming speed was no longer consistently associated with the reading and spelling skills of children with dyslexia. Finally, dyslexic children differed from normal readers on naming speed, literacy skills, phonological processing and processing speed, but not on inhibition processes. Both theoretical and clinical interpretations of these results are discussed.

Examining methodological variation in response inhibition: The effects of outcome measures and task characteristics on age-related differences

This study addressed methodological issues common to developmental studies on response inhibition. Age-related differences were investigated using two Stroop-like tasks with different levels of complexity and comparing different outcome measures in a sample of 340 children and adolescents aged 7-15 years. First, speed and accuracy of task performance were examined; the results showing that improvement in speed continued until age 13 in both the basic naming task and the two inhibition tasks. Improvement in accuracy was less consistent and continued until age 9 or 13 years. Second, two different algorithms were employed to control for the effects of basic processes in inhibition tasks. The difference algorithm indicated age-related differences similar to those for speed. The ratio algorithm, however, suggested earlier deceleration of development of response inhibition at 9 or 11 years of age. Factors related to the cognitive requirements and presented stimuli also had an effect on the results. The present findings shed light on the inconsistencies in the developmental studies of response inhibition and demonstrated that the selection of outcome measures and task characteristics are critical because they affect the way development is depicted.

Effect of methylphenidate on neurocognitive test battery: an evaluation according to the diagnostic and statistical manual of mental disorders, fourth edition, subtypes

The aims of this study were to evaluate the neuropsychological characteristics of the restrictive (R) subtype according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition and the attention-deficit/hyperactivity disorder (ADHD) combined (CB) type and predominantly inattentive (PI) type subtypes and to evaluate whether methylphenidate (MPH) affects neurocognitive test battery scores according to these subtypes. This study included 360 children and adolescents (277 boys, 83 girls) between 7 and 15 years of age who had been diagnosed with ADHD and compared the neuropsychological characteristics and MPH treatment responses of patients with the R subtype-which has been suggested for inclusion among the ADHD subtypes in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition-with those of patients with the PI and CB subtypes. They did not differ from the control subjects in the complex attention domain, which includes Continuous Performance Test, Stroop test, and Shifting Attention Test, which suggests that the R subtype displayed a lower level of deterioration in these domains compared with the PI and CB subtypes. The patients with the CB and PI subtypes did not differ from the control subjects in the Continuous Performance Test correct response domain, whereas those with the R subtype presented a poorer performance than the control subjects. The R subtype requires a more detailed evaluation because it presented similar results in the remaining neuropsychological evaluations and MPH responses.

Neuropsychological performance and attention-deficit hyperactivity disorder subtypes and symptom dimensions

OBJECTIVE

Characterization of clinical heterogeneity in attention-deficit hyperactivity disorder (ADHD) remains controversial. Neuropsychological and cognitive studies provide one type of validation data, but too often have considered only a narrow range of functional domains.

METHOD

The current study examined ADHD subtype and presentation differences across a broad range of neurocognitive domains in a large clinically characterized, community-recruited sample of 498 youth (213 control, 107 ADHD-primarily inattentive [ADHD-PI], 137 ADHD-combined [ADHD-C]), ages 6-17 years. Domains assessed included inhibition, working memory, arousal, processing speed, response variability, and temporal information processing.

RESULTS

Youth with ADHD-C performed worse than youth with ADHD-PI in all domains, consistent with a severity model. Performance among a subgroup with a "restrictive inattentive" presentation indicated potential deficits in processing speed relative to other ADHD-PI youth, but no other effects. When all measures were included in the same model, cognitive control (executive functions, working memory, and memory span), arousal, and response variability each provided uniquely incremental statistical prediction of specific symptom dimensions and of subtype/presentation, but temporal information processing and processing speed did not.

CONCLUSION

Results suggest the potential to consolidate multiple neurocognitive theories of ADHD, and that such consolidation will apply across putative clinical subtypes or presentations.

Long-term neurocognitive effects of methylphenidate in patients with attention deficit hyperactivity disorder, even at drug-free status

BACKGROUND

Methylphenidate (MPH), a psycho-stimulant, is the most widely administered drug for the pharmacological management of patients with attention deficit hyperactivity disorder (ADHD). This study attempts to determine whether sustainable improvements occur in neurocognitive function among ADHD patients following 12-month treatment with MPH, at drug-free status. Whether age groups, gender or ADHD subtypes differ in neurocognitive performance during MPH treatment is also examined.

METHODS

Study participants consisted of 103 ADHD patients (mean age: 9.1 ± 1.9 years old) who were drug naïve or drug free for at least 6 months. The patients were prescribed oral short-acting MPH at each dose range of 0.3-1.0 mg/kg daily. During 12 months of the study, the patients underwent the test of variables of attention (TOVA) at the baseline, month 6 and month12. Patients were instructed to not intake MPH for one week before the second and the third TOVA.

RESULTS

Seventy five patients completed the study. Results of this study indicated that although commission errors and response sensitivity (d') significantly improved during MPH treatment for 12 months, omission errors, response time, response time variability and ADHD score did not. While younger ADHD patients (<9 y/o) performed better in response time, response time variability, d' and ADHD score than older ones (≥9 y/o), the latter more significantly improved in response time than the former during 12 months of treatment. Additionally, boys improved more than girls in omission error and d'. Moreover, although ADHD subtypes significantly differed in ADHD score during the treatment, MPH treatment and ADHD subtypes did not interact with each other for all TOVA indices.

CONCLUSIONS

ADHD patients significantly improved in impulsivity and perceptual sensitivity, determined as TOVA, during MPH treatment for 12 months. Age and gender, yet not ADHD subtypes, appear to influence the MPH treatment effects in some indices of TOVA. A future study containing a comparison group is suggested to confirm whether the neurocognitive improvements are attributed to long-term effects of MPH or natural maturation of patients.

Current issues in the diagnosis of attention deficit hyperactivity disorder, oppositional defiant disorder, and conduct disorder

This review evaluates the diagnostic criteria for three of the most common disorders for which children and adolescents are referred for mental health treatment: attention deficit hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), and conduct disorder (CD). Although research supports the validity and clinical utility of these disorders, several issues are highlighted that could enhance the current diagnostic criteria. For ADHD, defining the core features of the disorder and its fit with other disorders, enhancing the validity of the criteria through the lifespan, considering alternative ways to form subtypes of the disorder, and modifying the age-of-onset criterion are discussed relative to the current diagnostic criteria. For ODD, eliminating the exclusionary criteria of CD, recognizing important symptom domains within the disorder, and using the cross-situational pervasiveness of the disorder as an index of severity are highlighted as important issues for improving classification. Finally, for CD, enhancing the current subtypes related to age of onset and integrating callous-unemotional traits into the diagnostic criteria are identified as key issues for improving classification.

External validation of bifactor model of ADHD: explaining heterogeneity in psychiatric comorbidity, cognitive control, and personality trait profiles within DSM-IV ADHD

The current paper provides external validation of the bifactor model of ADHD by examining associations between ADHD latent factor/profile scores and external validation indices. 548 children (321 boys; 302 with ADHD), 6 to 18 years old, recruited from the community participated in a comprehensive diagnostic procedure. Mothers completed the Child Behavior Checklist, Early Adolescent Temperament Questionnaire, and California Q-Sort. Children completed the Stop and Trail-Making Task. Specific inattention was associated with depression/withdrawal, slower cognitive task performance, introversion, agreeableness, and high reactive control; specific hyperactivity-impulsivity was associated with rule-breaking/aggressive behavior, social problems, errors during set-shifting, extraversion, disagreeableness, and low reactive control. It is concluded that the bifactor model provides better explanation of heterogeneity within ADHD than DSM-IV ADHD symptom counts or subtypes.