Treatment effects of methylphenidate on cognitive functioning in children with mental retardation and ADHD

Predicting the Response of Children and Adolescents With ADHD to Methylphenidate: A Systematic Review

OBJECTIVE

To report the characteristics associated with response to methylphenidate (MPH) in children and adolescents with ADHD.

METHODS

Studies reporting potentials predictors of response to MPH were searched in Medline and Embase from January 1998 to March 2022. Narrative synthesis was performed.

RESULTS

Fifty-seven reports of 46 studies totaling 6,656 ADHD patients were included. No association appears between response to MPH and age, gender, MPH dosage, ADHD subtype, comorbidities nor socioeconomic status when considering a specific patient. No conclusion could be drawn about body weight, ADHD severity, intelligence quotient, and parental symptoms of depression or ADHD.

CONCLUSIONS

None of these potential predictors have proven their usefulness to predict response to MPH on an individual basis in clinical practice. In research, potential predictors should be measured, their association with response to MPH assessed, in order to control for confounding variables when modeling response to MPH.

Translating methylphenidate's efficacy on selective and sustained attentional deficits to those reported in childhood cancer survivors: A qualitative review

Whilst an increasing number of children survive previously incurable cancers of the central nervous system (CNS), associated treatments often result in significant neurocognitive late effects. Methylphenidate provides some signs of alleviating cognitive difficulties in different pediatric groups; however, a minimal amount of systematic work has explored its effectiveness isolated to vulnerable attentional domains. The current review aimed to explore the effectiveness of methylphenidate isolated to two attentional domains (sustained and selective attention)-with an aim to substantiate its utility in childhood cancer survivors. Five databases were comprehensively searched for relevant articles. A purpose-developed tool was used to assess each study's robustness and research quality. Eleven out of 1,865 identified articles were included within the review. Studies drew upon five clinical populations. Individual attentional domains demonstrate variation in their response to methylphenidate. Sustained attention demonstrated the most consistent benefit of methylphenidate, reported largely in attention-deficit/hyperactivity disorder (ADHD) groups. Gains in selective attention and higher-order cognitive functions appeared to follow initial gains in sustained attention. Childhood cancer survivors report greater gains in selective attention compared to sustained attention. Higher doses may yield greater benefit for children with more diffuse attentional deficits. There is a need to improve the validity of current attentional measures before further methylphenidate trials are conducted.

Society for Developmental and Behavioral Pediatrics Clinical Practice Guideline for the Assessment and Treatment of Children and Adolescents with Complex Attention-Deficit/Hyperactivity Disorder

Attention-deficit/hyperactivity disorder (ADHD) is the most common childhood neurodevelopmental disorder and is associated with an array of coexisting conditions that complicate diagnostic assessment and treatment. ADHD and its coexisting conditions may impact function across multiple settings (home, school, peers, community), placing the affected child or adolescent at risk for adverse health and psychosocial outcomes in adulthood. Current practice guidelines focus on the treatment of ADHD in the primary care setting. The Society for Developmental and Behavioral Pediatrics has developed this practice guideline to facilitate integrated, interprofessional assessment and treatment of children and adolescents with "complex ADHD" defined by age (<4 years or presentation at age >12 years), presence of coexisting conditions, moderate to severe functional impairment, diagnostic uncertainty, or inadequate response to treatment.

ADHD severity as a predictor of cognitive task performance in children with Autism Spectrum Disorder (ASD)

BACKGROUND

In recent years, a number of studies have begun to explore the nature of Attention-Deficit/Hyperactivity Disorder (ADHD) in children with Autism Spectrum Disorder (ASD). In this study, we examined the relationship between both symptoms of ADHD and symptoms of ASD on cognitive task performance in a sample of higher-functioning children and adolescents with ASD. Participants completed cognitive tasks tapping aspects of attention, impulsivity/inhibition, and immediate memory.

AIMS

We hypothesized that children with ASD who had higher levels of ADHD symptom severity would be at higher risk for poorer sustained attention and selective attention, greater impulsivity/disinhibition, and weaker memory.

METHODS AND PROCEDURES

The sample included 92 children (73 males) diagnosed with ASD (Mean Age = 9.41 years; Mean Full Scale IQ = 84.2).

OUTCOMES AND RESULTS

Using regression analyses, more severe ADHD symptomatology was found to be significantly related to weaker performance on tasks measuring attention, immediate memory, and response inhibition. In contrast, increasing severity of ASD symptomatology was not associated with higher risk of poorer performance on any of the cognitive tasks assessed.

CONCLUSIONS AND IMPLICATIONS

These results suggest that children with ASD who have more severe ADHD symptoms are at higher risk for impairments in tasks assessing attention, immediate memory, and response inhibition-similar to ADHD-related impairments seen in the general pediatric population. As such, clinicians should assess various aspects of cognition in pediatric patients with ASD in order to facilitate optimal interventional and educational planning.

Effects of Extended-Release Methylphenidate Treatment on Cognitive Task Performance in Children with Autism Spectrum Disorder and Attention-Deficit/Hyperactivity Disorder

Objective: To examine the effectiveness of four doses of psychostimulant medication, combining extended-release methylphenidate (ER-MPH) in the morning with immediate-release MPH (IR-MPH) in the afternoon, on cognitive task performance. Method: The sample comprised 24 children (19 boys and 5 girls) who met the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition Text Revision (DSM-IV-TR) criteria for an autism spectrum disorder (ASD) on the Autism Diagnostic Interview-R and the Autism Diagnostic Observation Schedule, and had significant symptoms of attention-deficit/hyperactivity disorder (ADHD). This sample consisted of elementary school-age, community-based children (mean chronological age = 8.8 years, SD = 1.7; mean intelligence quotient = 85; SD = 16.8). Effects of placebo and three dose levels of ER-MPH (containing 0.21, 0.35, and 0.48 mg/kg equivalent of IR-MPH) on cognitive task performance were compared using a within-subject, crossover, placebo-controlled design. Each of the four MPH dosing regimens (placebo, low-dose MPH, medium-dose MPH, and high-dose MPH) was administered for 1 week; the dosing order was counterbalanced across children. Results: MPH treatment was associated with significant performance gains on cognitive tasks tapping sustained attention, selective attention, and impulsivity/inhibition. Dose/response was generally linear in the dose range studied, with no evidence of deterioration in performance at higher MPH doses in the dose range studied. Conclusion: The results of this study suggest that MPH formulations are associated with significant improvements on cognitive task performance in children with ASD and ADHD.

Clinical guidance on pharmacotherapy for the treatment of attention-deficit hyperactivity disorder (ADHD) for people with intellectual disability

INTRODUCTION

ADHD causes significant distress and functional impairment in multiple domains of daily life. Therefore, diagnosis and treatment are important to improve the quality of life of people. The pharmacotherapy for ADHD is well established but needs systematic evaluation in Intellectual Disability (ID) populations.

AREAS COVERED

This paper reviews the ADHD pharmacological treatment in people with ID using the PRISMA guidance for scoping reviews to help identify the nature and strength of evidence.

EXPERT OPINION

In the last 20 years, seven randomized controlled trials have evaluated pharmacotherapies for ADHD in people with ID; five looking at methylphenidate. Generally, studies were underpowered; all but two had less than 25 participants. Of the two larger trials one was single blinded and therefore open to bias. Only two used a parallel-group method, the remainder were mostly short crossover trials; not ideal when measuring behavioral and psychological parameters which are long standing. The remaining evidence is made up of observational studies. Methylphenidate and atomoxetine, particularly at higher doses, have shown clear benefits in people with ID. Most people with ID tolerated ADHD medications well. Benefits were seen in behavioral and/or cognitive domains. The evidence base is limited, though promising, for dexamfetamine, clonidine, and guanfacine.

The effects of methylphenidate on cognitive function in children with attention-deficit/hyperactivity disorder

Focusing on behavioral criteria for attention-deficit/hyperactivity disorder (ADHD) diagnosis leads to considerable neuropsychological profile heterogeneity among diagnosed children, as well as variable response to methylphenidate (MPH) treatment. Documenting "cold" executive working memory (EWM) or "hot" self-regulation (SR) neuropsychological impairments could aid in the differential diagnosis of ADHD subtypes and may help to determine the optimal MPH treatment dose. In this study, children with ADHD inattentive type (n = 19), combined type (n = 33), and hyperactive-impulse type (n = 4) underwent randomized controlled MPH trials; neuropsychological, behavioral, and observational data were collected to evaluate the children's responses. Those with moderate or significant baseline EWM/SR impairment showed robust MPH response, whereas response for those with lower baseline impairment was equivocal. Implications for medication use and titration, academic achievement, and long-term treatment efficacy are examined.

Clinical symptoms and performance on the Continuous Performance Test in children with attention deficit hyperactivity disorder between subtypes: a natural follow-up study for 6 months

BACKGROUND

The aims of this study were to determine the time course of improvements in attention deficit hyperactivity disorder (ADHD) clinical symptoms and neurocognitive function in a realistic clinical setting, and the differences in ADHD symptom improvement using different classifications of ADHD subtypes.

METHODS

The Child Behavior Checklist (CBCL) was completed by parents of ADHD children at the initial visit. The computerized Continuous Performance Test (CPT), Swanson, Nolan, and Pelham, and Version IV Scale for ADHD (SNAP-IV), and ADHD Rating Scale (ADHD-RS) were performed at baseline, one month, three months, and six months later, respectively. Patient care including drug therapy was performed at the discretion of the psychiatrist. The ADHD patients were divided into DSM-IV subtypes (Inattentive, Hyperactive-impulsive and Combined type), and were additionally categorized into aggressive and non-aggressive subtypes by aggression scale in CBCL for comparisons.

RESULTS

There were 50 ADHD patients with a mean age of 7.84 ± 1.64 years; 15 of them were inattentive type, 11 were hyperactive-impulsive type, and 24 were combined type. In addition, 28 of the ADHD patients were grouped into aggressive and 22 into non-aggressive subtypes. There were significant improvements in clinical symptoms of hyperactivity and inattention, and impulsivity performance in CPT during the 6-month treatment. The clinical hyperactive symptoms were significantly different between ADHD patients sub-grouping both by DSM-IV and aggression. Non-aggressive patients had significantly greater changes in distraction and impulsivity performances in CPT from baseline to month 6 than aggressive patients.

CONCLUSIONS

We found that ADHD symptoms, which included impulsive performances in CPT and clinical inattention and hyperactivity dimensions, had improved significantly over 6 months under pragmatic treatments. The non-aggressive ADHD patients might have a higher potential for improving in CPT performance than aggressive ones. However, it warrant further investigation whether the different classifications of ADHD patients could be valid for predicting the improvements in ADHD patients' clinical symptoms and neurocognitive performance.

Executive impairment determines ADHD medication response: implications for academic achievement

Methylphenidate (MPH) often ameliorates attention-deficit/hyperactivity disorder (ADHD) behavioral dysfunction according to indirect informant reports and rating scales. The standard of care behavioral MPH titration approach seldom includes direct neuropsychological or academic assessment data to determine treatment efficacy. Documenting "cool" executive-working memory (EWM) and "hot" self-regulation (SR) neuropsychological impairments could aid in differential diagnosis of ADHD subtypes and determining cognitive and academic MPH response. In this study, children aged 6 to 16 with ADHD inattentive type (IT; n = 19) and combined type (n = 33)/hyperactive-impulsive type (n = 4) (CT) participated in double-blind placebo-controlled MPH trials with baseline and randomized placebo, low MPH dose, and high MPH dose conditions. EWM/ SR measures and behavior ratings/classroom observations were rank ordered separately across conditions, with nonparametric randomization tests conducted to determine individual MPH response. Participants were subsequently grouped according to their level of cool EWM and hot SR circuit dysfunction. Robust cognitive and behavioral MPH response was achieved for children with significant baseline EWM/SR impairment, yet response was poor for those with adequate EWM/ SR baseline performance. Even for strong MPH responders, the best dose for neuropsychological functioning was typically lower than the best dose for behavior. Findings offer one possible explanation for why long-term academic MPH treatment gains in ADHD have not been realized. Implications for academic achievement and medication titration practices for children with behaviorally diagnosed ADHD will be discussed.

Salivary dehydroepiandrosterone, but not cortisol, is associated with attention deficit hyperactivity disorder

OBJECTIVES

The purposes of this study were to determine whether salivary levels of dehydroepiandrosterone (DHEA) and cortisol are associated with attention deficit hyperactivity disorder (ADHD) or correlated with performance on the Continuous Performance Test (CPT).

METHODS

Fifty ADHD patients and 50 age- and gender-matched controls aged between 6 and 12 years were included in this cross-sectional study. DHEA and cortisol levels were determined from saliva samples collected by the passive drool method at 08:00 h. ADHD patients subsequently performed a computerized Continuous Performance Test (CPT). ADHD symptoms were evaluated with the Swanson, Nolan, and Pelham, Version IV Scale for ADHD (SNAP-IV), completed by the patients' parents, and with the ADHD Rating Scale (ADHD-RS), administered by a child psychiatrist.

RESULTS

Saliva DHEA levels and DHEA/cortisol ratios differed significantly between ADHD patients and controls. Among ADHD patients, saliva DHEA levels and DHEA/cortisol ratios were independently correlated with composite scores of CPT distractibility and CPT impulsivity. Basal levels of cortisol were not significantly associated with ADHD.

CONCLUSIONS

DHEA, but not the cortisol basal level, may be a biological laboratory marker for ADHD, particularly for performance on the CPT. Both the causal relationship between DHEA and ADHD and the role of DHEA in treating ADHD require further investigation.

Parents report more ADHD symptoms than do teachers in children with epilepsy

Children with epilepsy have a high rate of attention deficit/hyperactivity disorder (ADHD), yet parent-teacher agreement on ADHD symptoms in epilepsy is unknown despite the need to assess symptoms across settings such as home and school. Parent-teacher agreement on ADHD ratings was investigated in 208 children with epilepsy (mean age = 11.2, SD = 3.6) using the ADHD Rating Scale IV, along with associations with demographic variables, epilepsy severity, adaptive level, and quality of life. Children were four times more likely to be identified as having clinically elevated ADHD symptoms when parent ratings were the benchmark versus teachers. Agreement was highest for children with more severe ADHD symptoms, for the Hyperactivity-Impulsivity dimension of behavior, and for children with broadly normal adaptive behavior. Higher parent and teacher ADHD ratings were related to reduced quality of life, but unrelated to epilepsy severity. Exclusive reliance on parent or teacher ratings may yield variable rates of ADHD symptoms in children with epilepsy.

Attention deficits, Attention-Deficit Hyperactivity Disorder, and intellectual disabilities

Attention-Deficit Hyperactivity Disorder (ADHD) and its earlier nosologic classifications have been extensively investigated since the 1960s, with PubMed listings alone exceeding 13,000 entries. Strides have been made in the diagnosis and treatment of ADHD in individuals with intellectual function in the normal range, as described in companion reviews in this special issue. In contrast, comparatively little is known about ADHD in intellectual developmental disabilities (IDD) despite the possibility that ADHD is statistically overrepresented among individuals with IDD (Pearson et al. 1997 Attention-deficit/hyperactivity disorder in mental retardation: nature of attention deficits. In: Burack J, Enns J, editors. Attention, development, and psychopathology. New York: Guilford Press. p 205-229; Pearson et al. 2000 Am. J. Ment. Retard. 105:236-251). Here, we provide a review of diagnostic controversies in ADHD with IDD, and discuss several topics that are currently attracting research efforts in the field. These include behavioral phenotyping and attempts to come to grips with problems of behavioral and etiological heterogeneity. Additionally, we consider issues relating to methodologically sound assessment of attention disorders and evidence-based intervention procedures that may clarify and/or ameliorate attention deficits in individuals with IDD.

Can Drug Treatments Enhance Learning in Subjects with Intellectual Disability?

Recent research has identified specific molecular mechanisms that might account for impaired learning in particular intellectual disability syndromes. These and other findings raise the possibility that targeted drug treatments might be developed to enhance learning in subjects with intellectual disability. This review considers strategies for developing treatments, and identifies critical issues that will need to be considered in such programmes.

Sustained attention and response inhibition in boys with fragile X syndrome: measures of continuous performance

Sustained attention and response inhibition were examined in boys with full mutation fragile X syndrome (FXS) using adapted visual and auditory continuous performance tests (CPTs). Only 61% of 56 boys with visual CPT data and 54% of 52 boys with auditory data were able to demonstrate sufficient understanding to complete the visual and auditory CPTs, respectively. Mental age (MA) predicted whether boys with FXS were able to demonstrate understanding of the CPTs. The performance of boys with FXS who were able to complete the CPTs was compared to a sample of boys without disabilities matched on MA. Boys with FXS demonstrated similar or smaller declines in sustained attention over task time than their MA-matched peers on the visual and auditory CPTs, respectively, but consistently demonstrated greater declines in response inhibition over task time than their MA-matched peers. There were no differences between groups for response time of hits. Higher MAs consistently predicted better sustained attention and response inhibition over task time on the visual and auditory CPTs. Furthermore, boys taking psychotropic medication performed better at the beginning of most tasks, although their performance deteriorated at a faster rate over time, and boys rated as meeting diagnostic criteria for ADHD-hyperactive type had more difficulty over task time with response inhibition on the auditory CPT. For both boys with FXS and their MA matches, performance was better on the visual CPT than on the auditory CPT though this effect may be attributable to a number of factors other than the modality.

A novel multidomain computerized cognitive assessment for attention-deficit hyperactivity disorder: evidence for widespread and circumscribed cognitive deficits

Multidomain assessment may enhance the diagnosis of cognitive impairment in children with attention-deficit hyperactivity disorder (ADHD). A set of novel Web-enabled computerized tests has recently been shown to be valid for identifying mild cognitive impairment and characterizing the cognitive profile associated with various disorders. It was anticipated that these tests would be well suited for use in children with ADHD. The authors tested this idea in a pilot study of 15 children (12 males, 3 females; mean age, 11 years 10 months; range, 9-15 years) with ADHD and 15 age-, education-, and gender-matched controls. The profile of cognitive impairment in ADHD children off methylphenidate across 6 cognitive domains (memory, executive function, visual-spatial skills, verbal function, attention, and motor skills) was described relative to controls. The effect of treatment with methylphenidate was examined by comparing the ADHD children on methylphenidate and on placebo (administered in a double-blind randomized fashion) relative to controls and by comparing the ADHD children on methylphenidate relative to placebo. Significant impairment in ADHD was evident in memory, visual-spatial, verbal, and attention domains, and near-significant impairment was observed in executive function and motor skills. On methylphenidate but not placebo, performance was comparable to controls in immediate verbal memory, psychomotor accuracy, visual-spatial, verbal rhyming, and overall battery performance. Significant improvement with administration of methylphenidate relative to placebo was evident for psychomotor accuracy, verbal rhyming, and overall battery performance. Hence, on the limited basis of this pilot study, the set of computerized tests studied appears to be useful for measuring cognitive function in ADHD; however, additional studies are needed to confirm this.

Dificuldades no diagnóstico de TDAH em crianças

O transtorno do déficit de atenção e/ou hiperatividade (TDAH) é uma doença de alta prevalência em crianças em idade escolar. Erroneamente entendido anteriormente como um diagnóstico de baixa morbidade, o TDAH é reconhecido atualmente como uma condição importante, não só pelo forte impacto funcional e social como também pela alta prevalência de comorbidades psiquiátricas. Déficits cognitivos globais e transtornos invasivos do desenvolvimento assim como transtornos do aprendizado são condições complexas que, quando estão associadas aos sintomas de TDAH, têm seus quadros agravados, requerendo maior atenção e estratégias de tratamento mais individualizadas. O objetivo deste artigo é uma discussão sobre esses diagnósticos diferenciais que representam um desafio na prática clínica.

Mental retardation in children ages 6 to 16

Mental retardation (MR) is a life long condition that affects 6 million American and 560,000 Canadian children under the age of 14. This review discusses the definition of MR, an approach to investigation, common comorbidities, and a general approach to management.

Atomoxetine for hyperactivity in autism spectrum disorders: placebo-controlled crossover pilot trial

OBJECTIVE

To explore placebo-controlled efficacy and safety of atomoxetine (ATX) for attention-deficit/hyperactivity disorder (ADHD) symptoms in children with autism spectrum disorders (ASD).

METHOD

Children ages 5 to 15 with ASD and prominent ADHD symptoms were randomly assigned to order in a crossover of clinically titrated ATX and placebo, 6 weeks each, separated by 1-week washout. Slopes for each condition were compared by paired t test.

RESULTS

In 2004-2005, 12 boys and 4 girls (7 with autistic disorder, 1 Asperger's, 8 pervasive developmental disorder not otherwise specified) all completed at least 3 weeks of each condition. On the primary outcome, the Hyperactivity subscale of the Aberrant Behavior Checklist, ATX was superior to placebo (p =.043, effect size d = 0.90). It was also superior on a 0 to 3 rating of nine DSM-IV ADHD hyperactive/impulsive symptoms (p =.005, d = 1.27), but missed significance on nine inattentive symptoms (p =.053, d= 0.89). Nine subjects responded to ATX, four to placebo (25% improvement on the Hyperactivity subscale plus Clinical Global Impressions-Improvement of 1-2. One was rehospitalized for recurrent violence on ATX. Adverse events were otherwise tolerable, with no tendency to stereotypy.

CONCLUSIONS

ATX appears safe and effective for treating hyperactivity in some children with autism spectrum disorders. The effect appears as large as in a multisite methylphenidate trial in the same population, with fewer intolerable side effects. Further study in autism spectrum disorders is indicated.

Is ADHD a valid disorder in children with intellectual delays?

To assess the validity of ADHD in children with mental retardation, we applied Robins and Guze's [Robins, E., and Guze, S.B. (1970). Establishment of diagnostic validity in psychiatric illness: Its application to schizophrenia. American Journal of Psychiatry, 126, 983-987.] criteria for determining the validity of a psychiatric disorder. We review the literature describing clinical correlates, family history, treatment response, laboratory studies, course, and outcome of children with ADHD and mental retardation. Although clearly an area in need of further research, there is preliminary evidence to suggest that ADHD is a valid psychiatric condition in children with mental retardation. Nevertheless, without knowing the base rates of ADHD symptoms in the mental retardation population, the positive predictive power and negative predictive power of ADHD symptoms in this population remain an open question. In addition to assessment of base rate symptoms, future research should consider what diagnostic algorithm may best be applied to the diagnosis of ADHD in mental retardation.

Disorders of attention or learning in neurodevelopmental disorders

Disorders of attention or learning commonly accompany neurodevelopmental disorders. The evaluation and diagnosis of these disorders is complex and does not always follow techniques used for typically developing children. These disorders are often underappreciated and inadequately addressed because they are overshadowed by the neurodevelopmental disorder. Nevertheless, failure to recognize, diagnose, and manage these disorders may result in unsuccessful community integration.

Attention-deficit/hyperactivity disorder among adolescents: a review of the diagnosis, treatment, and clinical implications

Attention-deficit/hyperactivity disorder (ADHD) is the most common mental disorder in childhood, and primary care clinicians provide a major component of the care for children with ADHD. However, because of limited available evidence, the American Academy of Pediatrics guidelines did not include adolescents and young adults. Contrary to previous beliefs, it has become clear that, in most cases, ADHD does not resolve once children enter puberty. This article reviews the current evidence about the diagnosis and treatment of adolescents and young adults with ADHD and describes how the information informs practice. It describes some of the unique characteristics observed among adolescents, as well as how the core symptoms change with maturity. The diagnostic process is discussed, as well as approaches to the care of adolescents to improve adherences. Both psychosocial and pharmacologic interventions are reviewed, and there is a discussion of these patients' transition into young adulthood. The article also indicates that research is needed to identify the unique adolescent characteristics of ADHD and effective psychosocial and pharmacologic treatments.

The use of psychostimulants in pervasive developmental disorders

Many children with Pervasive Developmental Disorders (PDD) display problematic behaviors similar to those seen in children with Attention Deficit Hyperactivity Disorder (ADHD). This paper will look at the controversy concerning diagnosing comorbid ADHD in children who meet criteria for PDD and review the existing literature examining the efficacy of stimulants in these particular set of behaviors or symptom clusters (hyperactivity, impulsivity and inattention). The potential drawbacks of using stimulants in a population of children and adolescents who exhibit symptoms of PDD and ADHD will be discussed. Finally, this review will also attempt to define potential areas of future research to examine the utility of the psychostimulants in children and adolescents with PDD and symptoms of ADHD.

Effects of methylphenidate treatment in children with mental retardation and ADHD: individual variation in medication response

OBJECTIVE

Individual variation in cognitive and behavioral response to methylphenidate (MPH) was investigated in children with mental retardation and attention-deficit/hyperactivity disorder.

METHOD

Twenty-four children (mean age 10.9 years, SD = 2.4) participated in a placebo-controlled, double-blind, crossover trial with 0.15-, 0.30-, and 0.60-mg/kg b.i.d. doses of MPH. Parent and teacher behavioral ratings, as well as cognitive task performance, were assessed at each dose.

RESULTS

Relative to placebo, most children with attention-deficit/hyperactivity disorder and mental retardation showed some degree of behavioral and cognitive improvement with MPH treatment. However, fewer of these children made substantial gains (>30% improvement, relative to placebo) with MPH treatment. At the highest dose, 55% of the children showed substantial behavioral gains and 46% made substantial gains in cognitive task performance. However, there was substantial independence between changes in behavior and changes in cognitive performance.

CONCLUSIONS

At the 0.60-mg/kg MPH dose, more children showed substantial cognitive and behavioral gains than those who showed substantial declines in a ratio of more than 5:1. However, it may be prudent to assess cognitive change as well as behavioral effects because improvements in the former do not necessarily forecast improvements in the latter in children with attention-deficit/hyperactivity disorder and mental retardation.