Evidence for unexpected weaknesses in learning in children with attention-deficit/hyperactivity disorder without reading disabilities

The reading-attention relationship: Variations in working memory network activity during single word decoding in children with and without dyslexia

This study utilized a neuroimaging task to assess working memory (WM) network recruitment during single word reading. Associations between WM and reading comprehension skills are well documented. Several converging models suggest WM may also contribute to foundational reading skills, but few studies have assessed this contribution directly. Two groups of children (77 developmental dyslexia (DD), 22 controls) completed a functional magnetic resonance imaging (fMRI) task to identify activation of a priori defined regions of the WM network. fMRI trials consisted of familiar word, pseudoword, and false font stimuli within a 1-back oddball task to assess how activation in the WM network differs in response to stimuli that can respectively be processed using word recognition, phonological decoding, or non-word strategies. Results showed children with DD recruited WM regions bilaterally in response to all stimulus types, whereas control children recruited left-lateralized WM regions during the pseudoword condition only. Group-level comparisons revealed activation differences in the defined WM network regions for false font and familiar word, but not pseudoword conditions. This effect was driven by increased activity in participants with DD in right hemisphere frontal, parietal, and motor regions despite poorer task performance. Findings suggest the WM network may contribute to inefficient decoding and word recognition strategies in children with DD.

Assessment of learning and memory impairments in adults with predominately inattentive versus combined presentation attention-deficit/hyperactivity disorder

This cross-sectional study compared adults diagnosed with Attention-Deficit/Hyperactivity Disorder-Inattentive (ADHD-I) and ADHD-Combined (ADHD-C) presentations with a non-ADHD group on verbal and visual learning and delayed recall using the Rey Auditory Verbal Learning Test (RAVLT) and Brief Visuospatial Memory Test-Revised (BVMT-R), respectively. Data from 380 predominately college student adult outpatients were used, with 155 who met criteria for ADHD-I, 165 who met criteria for ADHD-C, and 60 who did not meet criteria for ADHD but were diagnosed with a primary depressive or anxiety disorder or received no diagnosis. Each patient was administered the RAVLT and BVMT-R as part of a comprehensive neuropsychological evaluation. Significant main effects of study group were found, such that patients with ADHD-C demonstrated worse learning and delayed recall of both verbal and visual information than patients with ADHD-I and the non-ADHD group. Patients with ADHD-I performed comparably to the non-ADHD group, apart from visual learning and delayed recall. Notably, more patients in the ADHD groups had possible or probable learning and memory impairment compared to the non-ADHD group. Findings were consistent with previous research indicating that those with ADHD exhibit poorer verbal and visual learning and delayed recall than those without ADHD.

Verbal Memory Interference in Attention-Deficit Hyperactivity Disorder: A Meta-Analytic Review

OBJECTIVE

Interference control is used to overcome conflict among competing memory representations and may contribute to memory difficulties in ADHD. This meta-analytic review examined memory interference to evaluate susceptibility to proactive, retroactive, and memory control interference among those with ADHD.

METHOD

Twenty studies (1987-2019) examining verbal memory interference in ADHD met inclusion criteria (age: 8-36 years). Proactive and retroactive interference indices were extracted from list-learning tasks, and memory control indices were extracted from experimental paradigms (e.g., directed-forgetting).

RESULTS

Children with ADHD were less affected by proactive interference (g=-0.53, 95% CI [-0.75, -0.31]), whereas no significant differences were found in adults (g=0.13, 95% CI [-0.02, 0.28]). Adults and children with ADHD exhibited more retroactive interference (g=0.17, 95% CI [0.05, 0.29]) and performed worse on memory control tasks (g=0.35, 95% CI [0.08, 0.62]) relative to controls.

CONCLUSION

Differences in verbal memory interference control in ADHD were observed but effects were different depending upon interference type and participant age.

Verbal learning and memory in youth with neurofibromatosis type 1 and plexiform neurofibromas: Relationships with disease severity

AIM

To provide a comprehensive characterization of verbal learning and memory (VLM) abilities in youth with neurofibromatosis type 1 (NF1) and plexiform neurofibromas (PNs) and to evaluate disease severity as a predictor of VLM functioning over time.

METHOD

As part of a longitudinal natural history study, youth with NF1 and PNs were administered repeat neuropsychological assessments, including measures of VLM and ratings of NF1 disease severity completed by a medical professional. This sub-study analyzed data from 89 patients (M age baseline = 13.1, SD = 4.3 years, range 6-24 years) who had completed tests of VLM abilities and verbal attention at either baseline and/or 36 months.

RESULTS

VLM scores across the sample fell predominantly within the average range of functioning at both time points. However, relative to peers with mild NF1 disease severity, youth with moderate/severe NF1 disease showed lower functioning across multiple VLM domains at 36 months, even after controlling for the effects of verbal attention.

INTERPRETATION

Exclusive use of overall domain scores does not fully characterize VLM functioning in youth with NF1 and PNs. Additionally, children and adolescents with more severe NF1 disease should be monitored more closely for verbal memory challenges and targeted for interventions.

Recognition memory for pictures in children with ADHD: an event-related potential study

OBJECTIVE

Children with ADHD are reported to accompany by various degrees of recognition memory cognitive deficits. We aimed to investigate age-related changes of the amplitude in event-related potential recordings on recognition memory in Chinese children with ADHD and to provide theoretical basis of neuro-electrophysiology for the cognition development of children.

METHOD

ERP and behavioral data of 6- to -10-year-old children with ADHD (n = 94) and typically developing controls (TD, n = 96) were collected while the children performed a classical visual study-test paradigm task.

RESULTS

Children with ADHD have defects in pictures recognition and showed a significantly smaller P2 component than that of TD children. The development of P2 and P3 component were different between the two groups. Moreover, the TD children showed the frontal old/new effect (N2) taken as a correlate of familiarity at 6 years old, and a parietal old/new effect (P3) taken as a correlate of recollection at 9 years old, while children with ADHD showed a parietal old/new effect (P3) only at 6 years old.

CONCLUSION

Our study provided the novel evidence that recognition memory follow different developmental trajectories at the age of 6-10 between TD and ADHD.

Exploration of a novel virtual environment improves memory consolidation in ADHD

Experimental evidence in rodents and humans suggests that long-term memory consolidation can be enhanced by the exploration of a novel environment presented during a vulnerable early phase of consolidation. This memory enhancing effect (behavioral tagging) is caused by dopaminergic and noradrenergic neuromodulation of hippocampal plasticity processes. In translation from animal to human research, we investigated whether behavioral tagging with novelty can be used to tackle memory problems observed in children and adolescents with attention-deficit/hyperactivity disorder (ADHD). 34 patients with ADHD and 34 typically developing participants (age 9–15 years) explored either a previously familiarized or a novel virtual environment 45 min after they had learned a list of 20 words. Participants took a free recall test both immediately after learning the word list and after 24 h. Patients who explored a familiar environment showed significantly impaired memory consolidation compared to typically developing peers. Exploration of a novel environment led to significantly better memory consolidation in children and adolescents with ADHD. However, we did not observe a beneficial effect of novel environment exploration in typically developing participants. Our data rather suggested that increased exploration of a novel environment as well as higher feelings of virtual immersion compromised memory performance in typically developing children and adolescents, which was not the case for patients with ADHD. We propose that behavioral tagging with novel virtual environments is a promising candidate to overcome ADHD related memory problems. Moreover, the discrepancy between children and adolescents with and without ADHD suggests that behavioral tagging might only be able to improve memory consolidation for weakly encoded information.

Novel reading index for identifying disordered reading skill development: A preliminary study

Children with ADHD are at high risk of developing a Reading Disability (RD), although the reasons remain unclear. ADHD-associated impairments, including processing speed, can complicate clinical evaluation for a co-occurring RD diagnosis. We propose a novel metric to (a) assess reading development and (b) provide an alternative method to classifying readers that may aid investigations for etiologies of RD in ADHD. Specifically, as both phonological decoding and word recognition skills are important precursors of reading fluency, we propose a new quantitative method comparing these skills after accounting for variations in perception, motor response, or processing speeds. Forty boys (14 control, 15 ADHD, 11 ADHD/ + RD) completed a lexical decision task testing decoding and another assessing word recognition. Response time data was modeled using a Drift Diffusion approach to estimate the underlying reading skills. Using these reading skill estimates, we calculated a novel Reading Tendency Index and classified participants into three reading groups (Decoders, Balanced Readers, and Sight Readers). The reading and cognitive performance of these groups were consistent with theoretical predictions and subsequently provided external validity for the novel Reading Tendency Index classification. Our findings demonstrate a potential classification tool for readers based on individual's developed, reading tendencies.

Children and adolescents' performance on a medium-length/nonsemantic word-list test

Word-list learning tasks are among the most important and frequently used tests for declarative memory evaluation. For example, the California Verbal Learning Test-Children's Version (CVLT-C) and Rey Auditory Verbal Learning Test provide important information about different cognitive-neuropsychological processes. However, the impact of test length (i.e., number of words) and semantic organization (i.e., type of words) on children's and adolescents' memory performance remains to be clarified, especially during this developmental stage. To explore whether a medium-length non-semantically organized test can produce the typical curvilinear performance that semantically organized tests produce, reflecting executive control, we studied and compared the cognitive performance of normal children and adolescents by utilizing mathematical modeling. The model is based on the first-order system transfer function and has been successfully applied to learning curves for the CVLT-C (15 words, semantically organized paradigm). Results indicate that learning nine semantically unrelated words produces typical curvilinear (executive function) performance in children and younger adolescents and that performance could be effectively analyzed with the mathematical model. This indicates that the exponential increase (curvilinear performance) of correctly learned words does not solely depend on semantic and/or length features. This type of test controls semantic and length effects and may represent complementary tools for executive function evaluation in clinical populations in which semantic and/or length processing are affected.

Long-Term Memory Performance in Adult ADHD

OBJECTIVE

Memory problems are a frequently reported symptom in adult ADHD, and it is well-documented that adults with ADHD perform poorly on long-term memory tests. However, the cause of this effect is still controversial. The present meta-analysis examined underlying mechanisms that may lead to long-term memory impairments in adult ADHD.

METHOD

We performed separate meta-analyses of measures of memory acquisition and long-term memory using both verbal and visual memory tests. In addition, the influence of potential moderator variables was examined.

RESULTS

Adults with ADHD performed significantly worse than controls on verbal but not on visual long-term memory and memory acquisition subtests. The long-term memory deficit was strongly statistically related to the memory acquisition deficit. In contrast, no retrieval problems were observable.

CONCLUSION

Our results suggest that memory deficits in adult ADHD reflect a learning deficit induced at the stage of encoding. Implications for clinical and research settings are presented.

Functional Decoding and Meta-analytic Connectivity Modeling in Adult Attention-Deficit/Hyperactivity Disorder

BACKGROUND

Task-based functional magnetic resonance imaging (fMRI) studies of adult attention-deficit/hyperactivity disorder (ADHD) have revealed various ADHD-related dysfunctional brain regions, with heterogeneous findings across studies. Here, we used novel meta-analytic data-driven approaches to characterize the function and connectivity profile of ADHD-related dysfunctional regions consistently detected across studies.

METHODS

We first conducted an activation likelihood estimation meta-analysis of 24 task-based fMRI studies in adults with ADHD. Each ADHD-related dysfunctional region resulting from the activation likelihood estimation meta-analysis was then analyzed using functional decoding based on ~7500 fMRI experiments in the BrainMap database. This approach allows mapping brain regions to functions not necessarily tested in individual studies, thus suggesting possible novel functions for those regions. Additionally, ADHD-related dysfunctional regions were clustered based on their functional coactivation profiles across all the experiments stored in BrainMap (meta-analytic connectivity modeling).

RESULTS

ADHD-related hypoactivation was found in the left putamen, left inferior frontal gyrus (pars opercularis), left temporal pole, and right caudate. Functional decoding mapped the left putamen to cognitive aspects of music perception/reproduction and the left temporal lobe to language semantics; both these regions clustered together on the basis of their meta-analytic functional connectivity. Left inferior gyrus mapped to executive function tasks; right caudate mapped to both executive function tasks and music-related processes.

CONCLUSIONS

Our study provides meta-analytic support to the hypothesis that, in addition to well-known deficits in typical executive functions, impairment in processes related to music perception/reproduction and language semantics may be involved in the pathophysiology of adult ADHD.

Development of graphomotor fluency in adults with ADHD: Evidence of attenuated procedural learning

PURPOSE

The present study sought to determine if adults with ADHD demonstrate reduced graphomotor learning relative to controls.

METHOD

Twenty-eight control adults (n=14) and adults with ADHD (n=14) were recruited and wrote a novel grapheme on a digitizing tablet 30 times. Participants with ADHD were counterbalanced on and off stimulant medication.

RESULTS

Control participants, F(1,13)=13.786, p=.003, ω(2)partial=.460, and participants with ADHD on medication, F(1,13)=10.462, p=.007, ω(2)partial=.387, demonstrated significant improvement in graphomotor fluency with equivalent practice whereas participants with ADHD off medication did not, F(1,12)=0.166, NS.

CONCLUSIONS

Results indicate that graphomotor program learning in adults with ADHD may occur more slowly than typically developing peers. Findings have implications for providing accommodations to adults with ADHD, potential benefits of stimulant medication, and using digitizing technology as a neuropsychological assessment instrument.

Methylphenidate Efficacy: Immediate versus Extended Release at Short Term in Mexican Children with ADHD Assessed by Conners Scale and EEG

Attention deficit hyperactivity disorder (ADHD) affects 5-6% of school aged children worldwide. Pharmacological therapy is considered the first-line treatment and methylphenidate (MPH) is considered the first-choice medication. There are two formulations: immediate release (IR) MPH and long-acting (or extended release) formulation (MPH-ER). In this work, we measure the efficacy of treatment for both presentations in one month with Conners' scales and electroencephalography (EEG). Results. for IR group, in parents and teachers Conners test, all items showed significant differences, towards improvement, except for teachers in perfectionism and emotional instability. For ER group in parent's Conners test, the items in which there were no significant differences are psychosomatic and emotional instability. For teachers, there were no significant differences in: hyperactivity and perfectionism. Comparing the Conners questionnaires (parents versus teachers) we find significant differences before and after treatment in hyperactivity, perfectionism, psychosomatics, DSM-IV hyperactive-impulsive, and DSM-IV total. In the EEG the Wilcoxon test showed a significant difference (P < 0.0001). As we can see, both presentations are suitable for managing the ADHD and have the same effect on the symptomatology and in the EEG.

Transcranial oscillatory direct current stimulation during sleep improves declarative memory consolidation in children with attention-deficit/hyperactivity disorder to a level comparable to healthy controls

BACKGROUND

Slow oscillations (<1 Hz) during slow wave sleep (SWS) promote the consolidation of declarative memory. Children with attention-deficit/hyperactivity disorder (ADHD) have been shown to display deficits in sleep-dependent consolidation of declarative memory supposedly due to dysfunctional slow brain rhythms during SWS.

OBJECTIVE

Using transcranial oscillating direct current stimulation (toDCS) at 0.75 Hz, we investigated whether an externally triggered increase in slow oscillations during early SWS elevates memory performance in children with ADHD.

METHODS

12 children with ADHD underwent a toDCS and a sham condition in a double-blind crossover study design conducted in a sleep laboratory. Memory was tested using a 2D object-location task. In addition, 12 healthy children performed the same memory task in their home environment.

RESULTS

Stimulation enhanced slow oscillation power in children with ADHD and boosted memory performance to the same level as in healthy children.

CONCLUSION

These data indicate that increasing slow oscillation power during sleep by toDCS can alleviate declarative memory deficits in children with ADHD.

Learning and memory impairments in children and adolescents with attention-deficit/hyperactivity disorder

There are relatively few studies on learning and delayed memory with attention-deficit/hyperactivity disorder (ADHD). The objective of the present study was to examine acquisition, free delayed memory, and recognition skills in medication naive children and adolescents aged 8-16 years with ADHD combined subtype (36 participants) and inattentive subtype (45) compared to 50 healthy controls (HC) aged 8-17 years. Learning and delayed memory were assessed with the Hopkins Verbal Learning Test-Revised and the Brief Visuospatial Memory Test-Revised, which have compatible methods of administration, test format, and score ranges. The results showed that children with both ADHD subtypes scored significantly below HC in acquisition, free delayed memory, and recognition, even when controlling for the effect of IQ. Comparing phases in the learning process showed an initial deficit in acquisition but no increase in effect size in subsequent testing of free delayed memory or recognition. The study indicates that learning and delayed memory processes are impaired in both combined and inattentive subtypes of ADHD and that the deficits are not merely an artifact of IQ. The study indicates that emphasis must be put on the acquisition phase and how students with ADHD organize and encode new information.

Symptoms of ADHD in children with high-functioning autism are related to impaired verbal working memory and verbal delayed recall

Symptoms similar to those found in Attention-Deficit/Hyperactivity Disorder (ADHD) often occur in children with Autism Spectrum Disorders (ASD). The objective of the current study was to compare verbal working memory, acquisition and delayed recall in children with High-Functioning Autism (HFA) to children with ADHD and typically developing children (TDC). Thirty-eight children with HFA, 79 with ADHD and 50 TDC (age 8–17) were assessed with a letter/number sequencing task and a verbal list-learning task. To investigate the possible influence of attention problems in children with HFA, we divided the HFA group into children with (HFA+) or without (HFA−) “attention problems” according to the Child Behaviour Checklist 6–18. The children with HFA+ displayed significant impairment compared to TDC on all three neurocognitive measures, while the children with HFA− were significantly impaired compared to TDC only on the working memory and acquisition measures. In addition, the HFA+ group scored significantly below the HFA− group and the ADHD group on the verbal working memory and delayed recall measures. The results support the proposition that children with HFA+, HFA−, and ADHD differ not only on a clinical level but also on a neurocognitive level which may have implications for treatment.

A camp-based psychosocialiIntervention to promote independence and social function in individuals with spina bifida: moderators of treatment effectiveness

PURPOSE

To replicate and extend O'Mahar and colleagues' (O'Mahar, K., Holmbeck, G. N., Jandasek, B., & Zuckerman, J. [2010]. A camp-based intervention targeting independence among individuals with spina bifida. Journal of Pediatric Psychology, 35, 848-856) findings in a new and larger sample of youth and young adults with spina bifida who participated in a modified camp-based intervention targeting independence and social skills. Moderators of intervention effectiveness and clinical significance were examined.

METHOD

In all, 119 campers aged 7-41 years participated in an intervention that included goal setting and interactive workshops. Campers and parents completed measures of campers' goal attainment, independence, and social functioning at preintervention and postintervention; counselors reported on campers' goal attainment daily throughout the intervention.

RESULTS

Parents and campers reported improvements in campers' goal attainment, management of health-related self-care, and independence. Although benefits were found for most campers, cognitive functioning and family income moderated some outcomes. Campers who improved most on their social goals perceived the intervention to be more effective.

CONCLUSIONS

Further support is provided for the effectiveness of a camp-based intervention targeting independence and social skills for individuals with spina bifida. More attention should be directed toward those with cognitive difficulties and low-income backgrounds.

Clinical use of a modified release methylphenidate in the treatment of childhood attention deficit hyperactivity disorder

Attention deficit hyperactivity disorder (ADHD) is the most commonly diagnosed neurobehavioural disorder in childhood, affecting over 5% of children worldwide. As well as the core symptoms of inattention, hyperactivity and impulsivity, patients often exhibit learning difficulties and impairment in social functioning. The frequency of referral is higher for boys than for girls (about 2:1), and girls are generally older at the time of referral.Pharmacological therapy is considered the first-line treatment for patients with severe ADHD and severe impairment. Stimulant medications are licensed in the UK for the management of ADHD in school-age children and young people, and are effective in controlling ADHD symptoms.While immediate-release preparations of methylphenidate (MPH) have proven effective in the treatment of ADHD, there are a number of problems associated with their use, most notably compliance, stigma and medication diversion. Modified release preparations are now available that overcome the need for multiple daily dosing, and which offer different MPH release profiles, thereby enabling the physician to match the medication to the patient's particular requirements.This review describes the diagnosis, referral and treatment pathways for patients with ADHD in the UK and the practical considerations when initiating pharmacological treatment. The clinical experience of treating ADHD with a modified-release MPH preparation (Equasym XL®) is illustrated with case studies.

Comparison of verbal learning and memory in children with heavy prenatal alcohol exposure or attention-deficit/hyperactivity disorder

BACKGROUND

Children with fetal alcohol spectrum disorders (FASD) have deficits in verbal learning and recall. However, the specificity of these deficits has not been adequately tested. In the current study, verbal learning and memory performance of children with heavy prenatal alcohol exposure was compared to children with attention-deficit/hyperactivity disorder (ADHD), a disorder commonly seen in alcohol-exposed children.

METHODS

Performance on the California Verbal Learning Test-Children's Version (CVLT-C) was examined in 3 groups of children (N=22/group): (i) heavy prenatal alcohol exposure and ADHD (ALC), (ii) nonexposed with ADHD (ADHD), and (iii) nonexposed typically developing (CON). Groups were matched on age, sex, race, ethnicity, handedness, and socioeconomic status (SES).

RESULTS

Group differences were noted on learning trials (CON >ADHD> ALC). On the delayed recall trial, CON children performed better than both clinical groups, who did not differ from each other. Children in the ALC group demonstrated poorer recognition than children in the CON and ADHD groups, who did not differ from each other. Marginally significant group differences were noted on retention of previously learned material. Post hoc analyses indicated that ADHD children showed worse retention relative to the CON group, whereas retention in the ALC children remained intact.

CONCLUSIONS

These data suggest that children with heavy prenatal alcohol exposure and nonexposed children with ADHD show differential patterns of deficit on the CVLT-C. Performance of alcohol-exposed children reflects inefficient encoding of verbal material, whereas performance of the ADHD group may be better characterized by a deficit in retrieval of learned material. Differences noted between clinical groups add to a growing neurobehavioral profile of FASD that may aid in differential diagnosis.

An observational study of once-daily modified-release methylphenidate in ADHD: effectiveness on symptoms and impairment, and safety

ADHD affects over 5% of children worldwide. It is typically treated with stimulant medications, and methylphenidate (MPH) is the most commonly prescribed. This study investigated the effectiveness, on symptoms and impairment, and safety of Equasym XL(®), a combination of 30% immediate-release and 70% modified-release MPH, in the treatment of ADHD in daily clinical practice. This open-label, observational, post-marketing surveillance study was conducted in 169 centres in Germany. Eligible patients, aged 6-17 years, were diagnosed with ADHD and about to begin treatment with Equasym XL(®). Effectiveness was assessed by physicians using the clinical global impression (CGI) severity and improvement scales; teachers and parents completed questionnaires evaluating ADHD symptoms and behavioural problems (DAYAS, FBB-ADHD and SDQ-P). Assessments were carried out at baseline, after 1-3 and 6-12 weeks of treatment. Of 852 enrolled patients, 822 were evaluable; 25.30% were treatment naïve, 69.84% had previously received different MPH formulations, and 4.87% had received other medications. ADHD symptoms improved from baseline to last visit for the majority of patients for all outcome measures. According to physician ratings of core ADHD symptoms, 75.73% of patients showed improvements on the CGI-Improvement scale, 17.77% had no change, and 6.50% worsened. In teacher and parent ratings, the effectiveness of Equasym XL(®) was rated better than prior therapy at all measured time points across the day, particularly late morning (teachers) and early afternoon (parents). Equasym XL(®) was generally well tolerated; only 3.16% of patients permanently discontinued treatment due to adverse events. Equasym XL(®) is effective and well tolerated in daily clinical practice.

Do low-effort learning strategies mediate impaired memory in ADHD?

As a group, participants with attention-deficit/hyperactivity disorder (ADHD) are impaired in academic performance and learning. This may be due to a mild intellectual impairment, impaired attention, or inability to allocate sufficient effort. If the latter is the case, this should be evident in the learning strategies applied. Four indices of learning strategy, considered to measure degree of effort, were analyzed from 67 participants with ADHD and 67 age-matched normal controls between 9 and 16 years of age. The participants with ADHD were impaired with regard to semantic clustering, retroactive interference, and percentage items reported from the middle section of the list even when controlling for IQ and comorbid conduct or oppositional defiant disorders symptoms. In addition, participants with combined ADHD (ADHD-C) did not display the normal proactive interference effect. The four effort indices explained 39% and 35% of the variance in free recall among participants with inattentive ADHD (ADHD-I) and ADHD-C, respectively. IQ was still significant when the effect of strategy measures were accounted for, whereas diagnosis was no longer significant when entered into the regression analysis after the effort indices. The study shows that participants with ADHD employ less effortful learning strategies than healthy controls and that low effort to a large degree can account for diagnosis related variance in memory performance.

Verbal short-term memory span in children: long-term modality dependent effects of intrauterine growth restriction

BACKGROUND

Recent reports showed that children born with intrauterine growth restriction (IUGR) are at greater risk of experiencing verbal short-term memory span (STM) deficits that may impede their learning capacities at school. It is still unknown whether these deficits are modality dependent.

METHODS

This long-term, prospective design study examined modality-dependent verbal STM functions in children who were diagnosed at birth with IUGR (n = 138) and a control group (n = 64). Their STM skills were evaluated individually at 9 years of age with four conditions of the Visual-Aural Digit Span Test (VADS; Koppitz, 1981): auditory-oral, auditory-written, visuospatial-oral and visuospatial-written. Cognitive competence was evaluated with the short form of the Wechsler Intelligence Scales for Children--revised (WISC-R95; Wechsler, 1998).

RESULTS

We found IUGR-related specific auditory-oral STM deficits (p < .036) in conjunction with two double dissociations: an auditory-visuospatial (p < .014) and an input-output processing distinction (p < .014). Cognitive competence had a significant effect on all four conditions; however, the effect of IUGR on the auditory-oral condition was not overridden by the effect of intelligence quotient (IQ).

CONCLUSIONS

Intrauterine growth restriction affects global competence and inter-modality processing, as well as distinct auditory input processing related to verbal STM functions. The findings support a long-term relationship between prenatal aberrant head growth and auditory verbal STM deficits by the end of the first decade of life. Empirical, clinical and educational implications are presented.

Retrieval processes in adults with ADHD: a RAVLT study

Attention-deficit hyperactivity disorder (ADHD) is associated with memory deficiencies. In the current study we compared different aspects of verbal memory using standard and constructed measures of the Rey auditory verbal learning test (RAVLT). Performance on learning and recognition measures of RAVLT was similar in both ADHD and control groups. In contrast, adults with ADHD committed more double recalls and intrusion errors, indicating inaccurate recall processes. These findings suggest that memory problems in adults with ADHD may be caused by deficient executive processes that support retrieval from memory.

Process examination of executive function in ADHD: sex and subtype effects

To examine effects of group (Attention-Deficit/Hyperactivity Disorder [ADHD] versus Typically Developing [TD]), sex, and ADHD subtype on "process/optional" measures of executive functioning, children (n = 123; 54 ADHD, 69 TD) aged 8-16 completed subtests from the D-KEFS. No group, sex, or ADHD subtype effects were found on optional measures from the Trail Making, Color-Word Interference, and Tower tests. A significant interaction was found for Verbal Fluency Total Repetition Errors; boys with Combined/Hyperactive-Impulsive (ADHD-C/HI) type ADHD performed better than ADHD-C/HI girls, whereas girls with Inattentive type ADHD (ADHD-I) performed better than ADHD-I boys. Overall, children with ADHD did not differ from TD on most optional measures from the D-KEFS. When sex and ADHD subtype were considered, children with the subtype of ADHD less common for sex were at greater risk for poorer performance.

Prediction of ADHD in boys and girls using the D-KEFS

To examine patterns of executive dysfunction associated with ADHD, 123 children (54 ADHD, 69 controls) of ages 8-16 years were administered selected subtests from the Delis-Kaplan Executive Function System (D-KEFS). Children with ADHD performed significantly worse than controls on measures of both basic (less executive demand) skills and those with more executive demand from the Color-Word Interference and Tower subtests; however, no group differences were noted on any of the D-KEFS contrast scores. Most subtype comparisons yielded no differences; however, children with the Combined subtype outperformed children with the Inattentive subtype on measures of both basic and executive skills from the Trail Making Test. Children with ADHD demonstrate executive dysfunction that is identified by D-KEFS summary, but not contrast scores. In this carefully screened sample of children with ADHD, few significant differences were found between groups suggesting limited sensitivity or specificity of the D-KEFS for classifying children with ADHD.

The Factor Structure of the CVLT-C in Pediatric Epilepsy

The current study used archival data to evaluate the fit of six latent variable models, originally generated by Donders (1999), for the California Verbal Learning Test-Children's Version (CVLT-C; Delis, Kramer, Kaplan, & Ober, 1994) in a large (N = 289) sample of pediatric epilepsy cases presenting at three tertiary treatment centers. Using confirmatory factor analysis, we found that a model including factors of Attention Span, Learning Efficiency, Free Delayed Recall, Cued Delayed Recall, and Inaccurate Recall demonstrated the best relative fit for our data. These findings are consistent with those reported by Donders (1999) in his reanalysis of the CVLT-C standardization sample data, supporting the validity of this factorial model in pediatric epilepsy populations.

Comparison of the clinical efficacy of twice-daily Ritalin and once-daily Equasym XL with placebo in children with Attention Deficit/Hyperactivity Disorder

OBJECTIVE

To compare the efficacy and safety of two methylphenidate (MPH) formulations--once-daily modified-release MPH (EqXL, Equasym XL) and twice-daily immediate-release methylphenidate (MPH-IR, Ritalin)--and placebo in children with Attention Deficit/Hyperactivity Disorder (ADHD).

METHODS

Children aged 6-12 years on a stable dose of MPH were randomized into a double-blind, three-arm, parallel-group, multi-center study and received 3 weeks of EqXL (20, 40, or 60 mg qd), MPH-IR (10, 20, or 30 mg bid) or placebo. Non-inferiority of EqXL to MPH-IR was assessed by the difference in the inattention/overactivity component of the overall teacher's IOWA Conners' Rating Scale on the last week of treatment (per protocol population). Safety was monitored by adverse events, laboratory parameters, vital signs, physical exam, and a Side Effect Rating Scale.

RESULTS

The lower 97.5% confidence interval bound of the difference between MPH groups fell above the non-inferiority margin (-1.5 points) not only during the last week of treatment but during all three treatment weeks. Both MPH-treatment groups experienced superior benefit when compared to placebo during all treatment weeks (P < 0.001). All treatments were well tolerated.

CONCLUSIONS

EqXL given once-daily was non-inferior to MPH-IR given twice-daily. Both treatments were superior to placebo in reducing ADHD symptoms.

Attention-deficit hyperactivity disorder (ADHD) comorbidity: a case for "pure" Tourette syndrome?

More than a decade of research regarding the motoric characteristics of the attention-deficit hyperactivity disorder (ADHD) that accompanies Tourette syndrome has revealed unique anatomic and neurobehavioral differences and highlighted the importance of distinguishing children with this form from the 40% of children with Tourette syndrome who do not have ADHD. This distinction is important in providing guidance to parents and to patients and in formulating expectations for short- and long-term prognoses. In addition, study methodologies that fail to categorize patients in this way and instead involve covarying for dimensional symptoms of ADHD obscure biologically distinctive circuits and clinically meaningful patient characteristics.

Subtle executive impairment in children with autism and children with ADHD

BACKGROUND

The executive functions of inhibition, planning, flexible shifting of actions, and working memory are commonly reported to be impaired in neurodevelopmental disorders.

METHOD

We compared these abilities in children (8-12 years) with high functioning autism (HFA, n = 17), attention deficit-hyperactivity disorder (ADHD, n = 21) and healthy controls (n = 32). Response inhibition was assessed using the Stroop Color and Word Test (Golden, 1978). Problem solving, set-shifting, and nonverbal memory were assessed using three tasks, respectively, from the CANTAB (Cambridge Cognition, 1996): the Stockings of Cambridge task; the Intra-Dimensional/Extra-Dimensional set-shifting task; and the Spatial Working Memory task (SWM) with tokens hidden behind 3, 4, 6, and 8 boxes.

RESULTS

There were no group differences on the response inhibition, planning, or set-shifting tasks. On the SWM task, children with HFA made significantly more between-search errors compared with controls on both the most difficult problems (8-box) and on the mid-difficulty problems (6-box); however, children with ADHD made significantly more errors compared to controls on the most difficult (8-box) problems only.

CONCLUSION

Our findings suggest that spatial working memory is impaired in both ADHD and HFA, and more severely in the latter. More detailed investigation is needed to examine the mechanisms that differentially impair spatial working memory, but on this set of tasks there appears to be sparing of other executive functions in these neuropsychiatric developmental disorders.