The ecological validity of laboratory and analogue assessment methods of ADHD symptoms

Why obese children cannot resist food: the role of impulsivity

Facing the undesirable health consequences of being obese, an important question is why some people are not able to resist eating to excess. It is theorized that increased impulsivity at least partly underlies the inability to control eating behaviour; being more impulsive is supposed to make it more difficult to resist food intake. Thirty-three obese children in a residential setting and 31 lean control children are tested. Impulsivity is measured with two behavioural measures (inhibitory control and sensitivity to reward) and questionnaires. Results show that the obese children in treatment were more sensitive to reward and showed less inhibitory control than normal weight children. In addition, the obese children with eating binges were more impulsive than the obese children without eating binges. Most interesting finding was that the children that were the least effective in inhibiting responses, lost less weight in the residential treatment program. To conclude: impulsivity is a personality characteristic that potentially has crucial consequences for the development and maintenance, as well as treatment of obesity.

A computerized test of self-control predicts classroom behavior

We assessed choices on a computerized test of self-control (CTSC) for a group of children with features of attention deficit hyperactivity disorder (ADHD) and a group of controls. Thirty boys participated in the study. Fifteen of the children had been rated by their parents as hyperactive and inattentive, and 15 were age- and gender-matched controls in the same classroom. The children were observed in the classroom for three consecutive mornings, and data were collected on their activity levels and attention. The CTSC consisted of two tasks. In the delay condition, children chose to receive three rewards after a delay of 60 s or one reward immediately. In the task-difficulty condition, the children chose to complete a difficult math problem and receive three rewards or complete an easier problem for one reward. The children with ADHD features made more impulsive choices than their peers during both conditions, and these choices correlated with measures of their activity and attention in the classroom.

Effect of attentional state on frequency discrimination: a comparison of children with ADHD on and off medication

Debate continues over the hypothesis that children with language or literacy difficulties have a genuine auditory processing deficit. Several recent studies have reported deficits in frequency discrimination (FD), but it is unclear whether these are genuine perceptual impairments or reflective of the comorbid attentional problems that exist in many children with language and literacy difficulties. The present study investigated FD in children with attention deficit hyperactivity disorder (ADHD) when their attentional state was altered with stimulant medication. Auditory thresholds were obtained using FD and frequency modulation detection (FM) tasks. In the FD task, participants judged which of 2 pairs contained a high-low frequency sound, and in the FM task, children judged which of two tones "wobbled" (i.e., modulated). Children with ADHD had significantly poorer and more variable FD performance when off compared to on stimulant medication, and did significantly worse than controls on all FD runs when off but not on stimulant medication. However, children with ADHD did not differ from controls on the FM task. These findings demonstrate that certain auditory discrimination tasks are influenced by the child's attentional status. In addition, significant relationships between FD and measures of language and reading were abolished when comorbid attentional difficulties were taken into account. The study has implications for design and interpretation of studies investigating links between auditory discrimination and difficulties in language and literacy.

Impulsivity in obese women

In our obesogenic environment, self-control might be necessary in order to prevent overeating. Impulsivity is supposed to make it more difficult to resist the temptation to eat too much and can thereby contribute to overweight. In the present study, the hypotheses is tested that obese individuals are more impulsive. Thirty-one obese and 28 lean women, sampled from the normal population, are tested on a behavioural measure and three self-report measures of impulsivity. The obese women appeared more impulsive on the last part of the behavioural task, but not on the self-report measures. Implications of the results are discussed.

Development of visual attention skills in prelingually deaf children who use cochlear implants

OBJECTIVE

To determine the effects of length of cochlear implant use and other demographic factors on the development of sustained visual attention in prelingually deaf children and to examine the relations between performance on a test of sustained visual attention and audiological outcome measures in this population.

DESIGN

A retrospective analysis of data collected before cochlear implantation and over several years after implantation. Two groups of prelingually deaf children, one >6 years old (N = 41) and one <6 years old (N = 47) at testing, were given an age-appropriate Continuous Performance Task (CPT). In both groups, children monitored visually presented numbers for several minutes and responded whenever a designated number appeared. Hit rate, false alarm rate, and signal detection parameters were dependent measures of sustained visual attention. We tested for effects of a number of patient variables on CPT performance. Multiple regression analyses were conducted to determine if CPT scores were related to performance on several audiological outcome measures.

RESULTS

In both groups of children, mean CPT performance was low compared with published norms for normal-hearing children, and performance improved as a function of length of cochlear implant use and chronological age. The improvement in performance was manifested as an increase in hit rate and perceptual sensitivity over time. In the younger age group, a greater number of active electrodes predicted better CPT performance. Results from regression analyses indicated a relationship between CPT response criterion and receptive language in the younger age group. However, we failed to uncover any other relations between CPT performance and speech and language outcome measures.

CONCLUSIONS

Our findings suggest that cochlear implantation in prelingually deaf children leads to improved performance on a test of sustained visual processing of numbers over 2 or more years of cochlear implant use. In preschool-age children who use cochlear implants, individuals who are more conservative responders on the CPT show higher receptive language scores than do individuals with more impulsive response patterns. Theoretical accounts of these findings are discussed, including cross-modal reorganization of visual attention and enhanced phonological encoding of visually presented numbers.

An examination of the behavioral and neuropsychological correlates of three ADHD candidate gene polymorphisms (DRD4 7+, DBH TaqI A2, and DAT1 40 bp VNTR) in hyperactive and normal children followed to adulthood

Several candidate gene polymorphisms have been implicated in attention deficit hyperactivity disorder (ADHD), including DAT1 40bp VNTR, DRD4 7+, and DBH TaqI A2 alleles. We used the Milwaukee longitudinal study of hyperactive (n = 122) and normal (n = 67) children to compare participants with and without these respective polymorphisms on ADHD-related behavioral ratings at childhood, 8 years later in adolescence, and 13+ years later into young adulthood. Neuropsychological tests were given at the adolescent and young adulthood follow-up. No differences were found between the DRD4-7+ and 7- repeat polymorphism. The DBH TaqI A2 allele, when homozygous, was associated with being more hyperactive in childhood, having more pervasive behavior problems at adolescence, and earning less money on a card playing task in adulthood. At adolescence, poorer test scores were also found only in the hyperactive group with homozygous for this allele. The DAT1 40bp VNTR heterozygous 9/10 repeat, however, differed from the 10/10 repeat pair in many respects, having greater ADHD and externalizing symptoms at all three follow-ups, more cross-situational behavioral problems at both childhood and adolescence, poorer mother-teen relations at adolescence, and lower class rankings in high school. Participants with the 9/10 pair in the control group also had lower work performance, a lower grade point average in high school, greater teacher rated externalizing symptoms at adolescence, and greater omission errors on a continuous performance test in adulthood. The DAT1 40bp VNTR 9/10 polymorphism pairing appears to be reliably associated with greater symptoms of ADHD and externalizing behavior from childhood to adulthood, and with family, educational, and occupational impairments. We also present a contrary view on the appropriate endophenotypes for use in behavioral genetic research on ADHD.

Attentional functioning in children with ADHD - predominantly hyperactive-impulsive type and children with ADHD - combined type

Although particular importance has been attributed to attention deficits in attention deficit hyperactivity disorder (ADHD), there is no consensus as to the exact nature of inattention in ADHD or which components of attention are affected. The present study was based on a neuropsychological model of attention and assessed various components of attention in 23 children with ADHD/predominantly hyperactive-impulsive type (ADHD-H), 32 children with ADHD/combined type (ADHD-C) and healthy children (N(1) = 23 and N(2) = 32). A computerized test battery consisting of reaction time tasks of low complexity was used for the assessment of attention (alertness task, vigilance task, divided attention task, visual scanning task, incompatibility task, test of crossmodal integration, flexibility task). In comparison to healthy participants, patient groups were impaired in measures of vigilance, divided attention, selective attention and flexibility but not in measures of alertness. Analysis of the test performance of patient groups revealed no differences between children with ADHD-H and children with ADHD-C. The results of the present study suggest that both children with ADHD-H and children with ADHD-C are seriously impaired in attentional functioning. Children with ADHD-H and children with ADHD-C produced comparable results in measures of attention.

Effects of methylphenidate on multiple components of attention in children with attention deficit hyperactivity disorder

RATIONALE

Methylphenidate (MPH) has been shown to be effective in the treatment of attention deficits in children with attention deficit hyperactivity disorder (ADHD). Although a variety of studies have been performed, there is little available information as to which components of attentional functioning are disturbed in ADHD.

OBJECTIVES

The aim of the present study was to monitor the effect of MPH on various measures of attention in children with ADHD.

METHODS

In a double-blind, placebo-controlled, crossover study, the attentional functioning of 58 children diagnosed with ADHD without psychiatric comorbidity was examined. Assessment of attention was performed on their usual MPH treatment and following withdrawal of the drug. Furthermore, the attentional performance of 58 healthy children was assessed. The test battery consisted of reaction time tasks, including measures of alertness, vigilance, divided attention, flexibility, and aspects of selective attention such as focused attention, inhibition, and integration of sensory information.

RESULTS

In comparison to the test performance of healthy children, children with ADHD displayed impairments of vigilance, divided attention, flexibility, and aspects of selective attention including focused attention, inhibition, and integration of sensory information. Statistical comparison of attentional functioning of children with ADHD on and off MPH treatment revealed that the medication resulted in an improved task accuracy regarding vigilance, divided attention, inhibition, focused attention, integration of sensory information, and flexibility.

CONCLUSION

The present findings indicate that various aspects of attention are markedly impaired in children with ADHD. Treatment with MPH was accompanied by improvements in attention functions of small to moderate sizes. Although MPH-induced improvements were observed in a broad range of attention measures, children with ADHD who were on MPH treatment nevertheless displayed serious deficits in a number of components of attention.

Classroom attention in children with type 1 diabetes mellitus: the effect of stabilizing serum glucose

OBJECTIVE

To determine whether stabilizing serum glucose, via introduction of an insulin pump, improves classroom attention among children with type-1 diabetes mellitus.

STUDY DESIGN

Four boys having type-1 diabetes mellitus with unstable serum glucose were observed in their classroom for 10 baseline days. An insulin pump was placed and serum glucose stabilized, and they were then observed again for 10 days. A modified multiple baseline design was used to determine if improved on-task and off-task behavior was associated with better glycemic control. Rating scales and a laboratory measure of attention, measures of secondary interest, were also administered before and after pump introduction, and potential improvement in individuals' scores was evaluated.

RESULTS

All boys had apparent improvement in on-task and off-task behavior as observed in their classrooms. Improvements were substantial, averaging 20% in on-task behavior and 34% in off-task behavior. However, no changes were detected on rating scales or laboratory measures.

CONCLUSION

This study offers preliminary evidence that stabilizing serum glucose improves classroom attention, although the effect was detected only by observation of classroom behavior using highly structured techniques. Consequently, use of direct observation techniques may be important in studying the effects of chronic illness on classroom functioning.

Performance on a Visual Sustained Attention and Discrimination Task is Associated with Urinary Excretion of Norepineprhine Metabolite in Children with Attention-Deficit/Hyperactivity Disorder (AD/HD)

The degree of association between performance on a sustained attention task requiring visual discrimination and urinary excretion of catecholamine metabolites was examined in a cohort of 6- to 12-year-old children (n = 31) strictly selected and diagnosed with attention-deficit/hyperactivity disorder (AD/HD) according to DSM-IV and other strict criteria. Sustained visual attention and discrimination were measured using the Test of Variables of Attention (T.O.V.A.). Urinary excretion of dopamine (DA) and norepinephrine (NE) metabolites was measured by reversed high-pressure liquid chromatography (HPLC). Pearson product-moment correlations were used to investigate the relationship between T.O.V.A. errors of omission (OMM), errors of commission (COM), response time (RT), and response time variability (RTV) and catecholamine metabolites of DA and NE. All T.O.V.A. indexes under investigation were significantly correlated with urinary excretion of NE metabolites, but correlations were low-to-moderate in magnitude (.37-.50). In contrast, there were no statistically significant correlations between T.O.V.A. indices and DA metabolites. These findings and their concordance with past research in human adults and animals, as well as theoretical issues associated with the present results, are discussed.

How mothers parent their children with behavior disorders: implications for unintentional injury risk

INTRODUCTION

This study was designed to test the role of parental supervision in explaining why children with behavior disorders have increased risk of unintentional injury.

METHOD

Children referred to a pediatric behavior disorders clinic and their mothers were unknowingly observed in a "hazard room" environment that housed several items that appeared dangerous but actually were altered to be safe.

RESULTS

Mother and child behavior in the hazard room was correlated to parent-, teacher-, and observational-reports of children's externalizing behavior patterns, children's injury history, and mother's parenting styles. Maternal ignoring of children's dangerous behavior in the hazard room was the strongest correlate to children's injury history.

CONCLUSIONS

Poor parental supervision might serve as a mechanism to explain why children with behavior disorders, and those with oppositional behavior patterns in particular, have increased risk of unintentional injury.

Evidence-Based Assessment of Conduct Problems in Children and Adolescents

This article provides a summary of research in 4 areas that have direct and important implications for evidence-based assessment of children and adolescents with conduct problems (CP): (a) the heterogeneity in types and severity of CP, (b) common comorbid conditions, (c) multiple risk factors associated with CP, and (d) multiple developmental pathways to CP. For each of these domains, we discuss implications for evidence-based assessment, present examples of specific measures that can aid in such assessments, and provide recommendations for evidence-based assessment of CP in children and adolescents. We conclude that there is a need to (a) enhance the clinical utility of evidence-based measures for assessing CP; (b) increase attention to the sensitivity of such measures to change, for both treatment evaluation and monitoring; and (c) develop assessment methods that reliably and validly identify a child or adolescent's placement and progress on the various developmental pathways to CP.

Screening of developmental disorders in five-year-olds using the FTF (Five to Fifteen) questionnaire: a validation study

The study examined the validity of the Five to Fifteen (FTF) questionnaire in detecting developmental disorders in five-year-old children. A pilot study (N=70) was first undertaken to try out a translation of the FTF into Finnish. Subsequently, FTF questionnaires were mailed to parents of all five-year-old children from specified health-care districts in Vantaa, Finland. A total of 769 questionnaires (60%) were completed and returned. Children scoring above a cut-off value in any domain were considered at risk for having developmental disorders (the Risk Group; N=90). A Control Group was formed by randomly selecting 30 children who did not score above the threshold value in any domain. The children from the Risk Group and the Control Group were called to individual neuropsychological assessments. All invited children attended the assessments. The parts of the FTF that assess fine motor skills, executive functions (including attention and impulsivity), perception, memory, and language were used for this study. The external criterion measure was the NEPSY, a neuropsychological assessment instrument. Results demonstrated that the five FTF Domain Scores used in this study correlated significantly with the corresponding NEPSY Domain Scores. Second, the Risk Group obtained significantly poorer scores on the NEPSY than the Control Group. Third, on a cross-tabulation a very high rate of positive hits (93 %) was obtained as well as a very low rate of misses (7 %), indicating a very good sensitivity. However, there were a large percentage of false positives (63 %), indicating that specificity was not so good. Evidently, parents may report concerns related to the young child's development even when neuropsychological assessments do not indicate significant disorders. On the whole, the findings supported the validity of the FTF as a developmental screening instrument.

Neural Substrates of Childhood Attention-Deficit/Hyperactivity Disorder: Electroencephalographic and Magnetic Resonance Imaging Evidence

Research methods based on electroencephalogram (EEG) and anatomical and functional MRI have been used with increasing frequency in the study of childhood Attention-Deficit/Hyperactivity Disorder (ADHD). Both methods are safe and noninvasive, and their results can complement each other because of the good temporal (but relatively poorer spatial) resolution of EEG and the good spatial (but relatively poorer temporal) resolution of MRI. These methods are described, and associated recent research on childhood ADHD is summarized and critically examined. Results of this research support theories of ADHD that focus on a frontal-striatal neurological circuitry substrate, which has been implicated in neuropsychological executive functioning. A number of issues, however, such as the specificity of this finding for ADHD, remain unresolved. We conclude with an overview of advances and issues to be considered in future research on the neural substrates of childhood ADHD and advocate a developmental-contextual perspective on this disorder that acknowledges the reciprocal relations between neural structures and functions.

Time reproduction in finger tapping tasks by children with attention-deficit hyperactivity disorder and/or dyslexia

AIM

Deficits in timing and sequencing behaviour in children with dyslexia and with attention-deficit hyperactivity disorder have already been identified. However many studies have not controlled for comorbidity between dyslexia and ADHD. This study investigated timing performance of children with either dyslexia or ADHD, or ADHD + dyslexia or unaffected children using a finger tapping paradigm.

METHOD

Four groups of children (ADHD x Dyslexia) with a total of 68 children were compared using a four factorial design with two between-subject factors (ADHD (yes/no), dyslexia (yes/no)) and two within-subject factors, inter-stimulus interval (263, 500, 625, 750, 875 and 1000 ms) and tapping condition (free tapping, synchronous tapping, and unpaced tapping). In addition the complexity of rhythm reproduction pattern (unpaced tapping) was varied (simple/complex).

RESULTS

No significant differences were found either in the ability of the ADHD or the dyslexia groups to sustain a self-chosen free tapping rate or to generate a stable inter-response interval either by synchronising to a signal or in reproducing a given interval without the previous pacing signal. Response averages showed the expected asynchrony and variability. In rhythm pattern reproduction the groups did not differ significantly in their ability to reproduce rhythms. However, a significant two way interaction effect between dyslexia and complexity was apparent indicating that the difference in levels of performance for simple versus complex rhythms was more pronounced for dyslexia than for the two other groups.

CONCLUSION

The results indicate that motor timing ability in the millisecond range below 1000 ms in children with ADHD and/or dyslexia is intact. The performance of the comorbid group was revealed to be similar to the performance of the single disorder groups, but both the dyslexic groups were relatively worse than either the ADHD-only or the unimpaired group at reproducing complex versus simple rhythms.

Relationship between motor proficiency, attention, impulse, and activity in children with ADHD

The aim of this study was to investigate the relationship between motor performance, attention deficit, impulsiveness, and hyperactivity in children with attention-deficit--hyperactivity disorder (ADHD). Participants were 42 school-aged children with ADHD (36 males, 6 females; mean age 8 years 2 months, SD 1 year 2 months; range 6 years to 11 years), and 42 age- and sex-matched children without ADHD (mean age 8 years 3 months, SD 1 year 1 month; range 6 years to 11 years). Motor abilities were assessed with the Bruininks-Oseretsky Test of Motor Proficiency. Attention and impulse control were measured with the Gordon Diagnostic System, and assessment of activity level was based on two Activity Level Rating Scales that were completed by parents and teachers. Analysis by t-test revealed a significant difference between children with and without ADHD in fine and gross motor skills, impulse control, and attention. Stepwise regression indicated that attention, impulse control, and parent ratings of activity level were the three best predictors of gross motor skills for children with ADHD, accounting for 55.9% of the variance. Attention and impulse control were the two best predictors of fine motor skills, accounting for 45.7% of the variance. Attention and impulse control were consistently found to be important predictors of both fine and gross motor skills in children with ADHD. However, the fact that activity level was a predictor for gross motor proficiency but not for fine motor tasks suggests that different behavioral processes are involved in fine and gross motor performance to different extents.

The d2 Test of attention: construct validity and extensions in scoring techniques

The internal consistency and convergent and discriminant validity of the d2 Test, a cancellation test of attention and concentration, was examined in a sample of 364 U.S. adults. Test-taking strategy, new process scores for assessing performance constancy, and relations to gender and education were explored. Results suggested that the d2 Test is an internally consistent and valid measure of visual scanning accuracy and speed. Overall performance scores were related to a proxy measure of test-taking strategy in the expected direction, and new acceleration and deterioration measures exhibited convergent validity. Suggested directions for future research include discrimination of attentional processes that support immediate and sustained visual scanning accuracy and speed, further examination of the impact of test-taking strategies on overall performance measures, and additional construct validity examinations for the new process measures.

Behavioral impulsivity paradigms: a comparison in hospitalized adolescents with disruptive behavior disorders

BACKGROUND

Behavioral impulsivity paradigms vary widely and studies using these measures have typically relied on a single measure used in isolation. As a result, comparisons between measures are difficult, with little consensus regarding which method may be most sensitive to individual impulsivity differences of different populations.

METHOD

A single testing session of each of four different impulsivity tasks was completed by two groups of adolescents aged 13-17: hospitalized inpatients with disruptive behavior disorders (DBD; n = 22) and controls (n = 22). Tasks included two rapid-decision (IMT/DMT and GoStop) and two reward-directed (TC and SKIP) impulsivity paradigms. Behavioral testing took place within 3 days of hospitalization for the adolescents with DBD.

RESULTS

Compared to controls, the DBD group exhibited higher commission error rates, lower inhibited response rates after a stop-signal, and twice as many reward-directed responses even after IQ differences between the groups were taken into account. When the four paradigms were compared, effect-size calculations indicated that the two rapid-decision paradigms were more sensitive to group differences than the reward-directed tasks.

CONCLUSIONS

Despite the initiation of pharmacotherapy within the first 3 days of hospitalization, in contrast to the control group, the adolescents with DBD performed consistently with what has been operationally defined as impulsivity. Based on these results, these tasks appear to measure similar, but unique components of the impulsivity construct. With further study, laboratory behavioral paradigms may prove to be useful additions to current clinical diagnostic and treatment procedures in a variety of psychiatric populations.

Relations between Continuous Performance Test performance measures and ADHD behaviors

The Conners' Continuous Performance Test (CPT) is a neuropsychological task that has repeatedly been shown to differentiate ADHD from normal groups. Several variables may be derived from the Conners' CPT including errors of omission and commission, mean hit reaction time(RT), mean hit RT standard error, d', and beta. What each CPT parameter actually assesses has largely been based upon clinical assumptions and the face validity of each measure (e.g., omission errors measure inattention, commission errors measure impulsivity). This study attempts to examine relations between various CPT variables and phenotypic behaviors so as to better understand the various CPT variables. An epidemiological sample of 817 children was administered the Conners' CPT. Diagnostic interviews were conducted with parents to determine ADHD symptom profiles for all children. Children diagnosed with ADHD had more variable RTs, made more errors of commission and omission, and demonstrated poorer perceptual sensitivity than nondiagnosed children. Regarding specific symptoms, generalized estimating equations (GEE) and ANCOVAs were conducted to determine specific relationships between the 18 DSM-IV ADHD symptoms and 6 CPT parameters. CPT performance measures demonstrated significant relationships to ADHD symptoms but did not demonstrate symptom domain specificity according to a priori assumptions. Overall performance on the two signal detection measures, d' and beta, was highly related to all ADHD symptoms across symptom domains. Further, increased variability in RTs over time was related to most ADHD symptoms. Finally, it appears that at least 1 CPT variable, mean hit RT, is minimally related to ADHD symptoms as a whole, but does demonstrate some specificity in its link with symptoms of hyperactivity.

EEG biofeedback vs. placebo treatment for attention-deficit/hyperactivity disorder: a pilot study

METHOD

Seven children diagnosed with attention-deficit hyperactivity disorder (ADHD) were trained using a standard EEG biofeedback treatment protocol designed to alter SMR/theta ratios and reduce behavioral symptomatology diagnostic of ADHD. During alternate periods they were also trained using a placebo protocol that was identical to the treatment protocol, save that the association between EEG patterns and feedback to the participants was random. Single-case design elements were used to control for the effects of internal validity threats such as maturation, history, and treatment order. Two participants failed to complete all training sessions, and the effects of training on behavior were analyzed both including and excluding these non-completers.

RESULTS

When all participants were included in analyses that controlled for overall trend, EEG biofeedback was found to be no more effective than the placebo control condition involving non-contingent feedback, and neither procedure resulted in improvements relative to baseline levels. When overall behavioral trends unrelated to training were not controlled for and non-completers were excluded from the analysis, it could be mistakenly concluded that EEG biofeedback is significantly more effective than placebo and that the effect sizes involved are moderate to large. These results indicate that many previous reports of the efficacy of EEG biofeedback for ADHD, particularly those presenting series of single cases, might well have been based on spurious findings.

Glucose effects on a continuous performance test of attention in adults

Increases in plasma blood glucose levels modulate memory, mood, and, to some extent, attention in adults. Participants in the present study were administered glucose (10, 100, and 500 mg/kg, or 50 g) or placebo (23.7 mg saccharin) shortly prior to completing the test of variables of attention (TOVA), a continuous performance test (CPT) commonly used to assess attention for diagnostic purposes. There were significant increases in blood glucose levels for the 500 mg/kg and 50 g groups, but only the 100 mg/kg group showed significant changes in behavior in comparison to the saccharin group. Specifically, the 100 mg/kg group performed worse on measures of commission errors, post-commission responses, and post-commission response time variability. There were no differences among the groups on other major variables of attention, including omission errors, response time, and response time variability. The results of this study demonstrate that large doses of glucose which increase blood glucose levels do not influence attention, but that a moderate dose (100 mg/kg) selectively impairs measures of impulsivity or disinhibition. Practitioners and researchers should maintain an awareness of dietary effects on attention and continue to examine micronutrients as potential confounds on diagnostic tests of cognition and behavior.

Analog classroom assessment of a once-daily mixed amphetamine formulation, SLI381 (Adderall XR), in children with ADHD

OBJECTIVES

This investigation was conducted primarily to assess the safety and efficacy of SLI381 (Adderall XR), developed as a once-daily treatment for children with attention-deficit/hyperactivity disorder (ADHD). Secondary objectives included examination of the time course, pharmacokinetic, and pharmacodynamic properties of SLI381.

METHOD

This was a randomized, double-blind, crossover study of three doses of SLI381 (10, 20, and 30 mg), placebo, and an active control (Adderall 10 mg) given once daily to 51 children with ADHD. Weekly assessments in an analog classroom setting included blind ratings of attention and deportment and a performance measure (math test) obtained every 1.5 hours over a 12-hour period.

RESULTS

SLI381 was well tolerated. All active treatment conditions displayed significant time course effects and were superior to placebo in improving efficacy measures. Dose-dependent improvements were evident for SLI381. SLI381 20 and 30 mg and Adderall all showed rapid improvements by 1.5 hours, but only the SLI381 20- and 30-mg doses showed continued activity at 10.5 and 12 hours for classroom behavior and math test performance versus placebo.

CONCLUSIONS

These data provide support for the benefit of this novel, once-daily amphetamine preparation in the treatment of ADHD. The longer duration of action of SLI381 has the potential to simplify psychostimulant dosing, thus reducing dose diversion and eliminating the need for in-school administration. SLI381 appears to be a useful treatment option for many children with ADHD.

Animal models of attention-deficit hyperactivity disorder

Attention-deficit hyperactivity disorder (ADHD) involves clinically heterogeneous dysfunctions of sustained attention, with behavioral overactivity and impulsivity, of juvenile onset. Experimental models, in addition to mimicking syndromal features, should resemble the clinical condition in pathophysiology, and predict potential new treatments. One of the most extensively evaluated animal models of ADHD is the spontaneously hypertensive rat. Other models include additional genetic variants (dopamine transporter gene knock-out mouse, coloboma mouse, Naples hyperexcitable rat, acallosal mouse, hyposexual rat, and population-extreme rodents), neonatal lesioning of dopamine neurons with 6-hydroxydopamine, and exposure to other neurotoxins or hippocampal irradiation. None is fully comparable to clinical ADHD. The pathophysiology involved varies, including both deficient and excessive dopaminergic functioning, and probable involvement of other monoamine neurotransmitters. Improved models as well as further testing of their ability to predict treatment responses are required.

Familial transmission of Continuous Performance Test behavior: attentional and impulsive response characteristics

Continuous Performance Tests (CPTs) provide information on attentional processing and impulsive behavior. The results of previous research that used self-report measures have provided evidence for familial transmission (through genetic and/or environmental influences) of impulsive characteristics. The authors of the present study examined whether the impulsive behavioral parameters that are measured by the CPT also share familial relationships. The researchers asked 26 healthy parent-adolescent pairs to complete the Immediate and Delayed Memory Tasks (IMT/DMT; D. M. Dougherty, 1999; D. M. Dougherty, D. M. Marsh, & C. W. Mathias, 2002), a modified CPT (B. A. Cornblatt, N. J. Risch, G. Faris, D. Friedman, & L. Erlenmeyer-Kimling, 1988; H. E. Rosvold, A. Mirsky, I. Sarason, E. D. Breansome, Jr., & L. H. Beck, 1956), and the Barratt Impulsiveness Scale (BIS; J. H. Patton, M. S. Stanford, & E. S. Barratt, 1995), a self-report measure. The main findings can be summarized as follows: (a) commission errors (but not correct detections) on the IMT and DMT were correlated between parents and their adolescent children, (b) adolescents emitted a higher proportion of commission errors than did their parents, and (c) self-reported impulsivity (i.e., BIS) was correlated with commission errors for parents, but not for adolescents. The findings of this study support the use of an objective behavioral measure of impulsivity to assess familial relationships of impulsivity.

The Gordon Diagnostic System and WISC-III Freedom from Distractibility Index: validity in identifying clinic-referred children with and without ADHD

Gordon Diagnostic System and WISC-III scores for clinic-referred 6- to 16-yr.-olds (184 with ADHD Combined Type and 46 without ADHD) were analyzed to evaluate the combination of scores and cutpoints that maximized diagnostic accuracy. Using an "ADHD cutpoint" of IQ minus the GDS Composite score > or = 13, 87.8% of the children were correctly identified as having or not having ADHD. IQ minus Freedom from Distractibility > 0 yielded 73.5% accuracy. When the two meaures were combined to create new criteria (IQ minus GDS Composite > or = 13 or IQ minus Freedom from Distractibility > or = 11), diagnostic accuracy increased to 90.9% and negative predictive power improved substantially. Diagnostic agreement between the Gordon Diagnostic System and Freedom from Distractibility was 70%, suggesting that the two tests measure both similar and unique traits.

Separating genuine cases of reading disability from reading deficits caused by predominantly inattentive ADHD behavior

Conventional methods of differentiating reading disability (RD) caused by deficits in decoding skills or comprehension from poor reading performance caused by inconsistent attention associated with attention-deficit/hyperactivity disorder (ADHD) have produced equivocal results. This study presents a model of differential diagnosis of attentional problems and RD that differs from these conventional approaches. The new diagnostic procedure uses intraindividual differences seen in the performance of at-risk learners on tasks related to reading that vary in their sensitivity to the sustained attention required for successful performance. The hypothesis is that children with inconsistent attention would perform more poorly on tests that require sustained attention, such as listening comprehension, than on tests that are more tolerant of inattention, such as reading comprehension. Such differences would not be seen in the test scores of children who have only RD, because their performance is determined more by the difficulty level of the reading tests than by the degree of sensitivity of the task to attention. The validity of this new model was evaluated by determining the capability of the differences seen in the scores of tests that differ in their sensitivity to sustained attention to predict the degree of inconsistency in sustained attention as measured by a continuous performance test. The data obtained from 39 children who are at risk for RD suggest that this is a viable model.

Immediate and delayed memory tasks: a computerized behavioral measure of memory, attention, and impulsivity

The Immediate and Delayed Memory Task (IMT/DMT), a variant of the Continuous Performance Test (CPT), is a new software package designed to be a flexible research tool for the study of attention, memory, and impulsivity. This package allows researchers to determine the design to be used during a testing session and to manipulate many of the parameters. It features two components: the IMT and the DMT, both of which present sequential 2- to 7-digit stimuli with variable presentation rates and intertrial intervals. Subjects respond to identically matched stimuli presented consecutively, spanning a brief period of time (IMT), or to stimuli spanning a greater period of time (during which intervening stimuli to be ignored appear; DMT). Task complexity can be adjusted to suit applications for both children and adults. Preliminary studies have demonstrated that these laboratory tasks are sensitive to group differences, produce stable baselines of performance, and are sensitive to drug-induced performance decrements.

A meta-analytic examination of comorbid hyperactive-impulsive-attention problems and conduct problems

The author quantitatively reviewed prevalence rates, defining features, associated features, developmental trajectory, and etiology to examine 3 taxonomic questions about comorbid hyperactive-impulsive-attention problems (HIA) and conduct problems (CP): Do HIA and CP co-occur randomly? Does comorbid HIA-CP differ from HIA-only and CP-only? Do HIA and CP combine synergistically? Results showed that HIA and CP co-occur at a greater than random rate, that comorbid HIA-CP differs from HIA-only and CP-only in multiple ways, and that there is little evidence that HIA and CP combine synergistically. However, sample type, grouping definition, age, gender, and subtype of disruptive behavior often moderated these findings. Overall, the review suggests that HIA-CP is best conceptualized as an additive combination of HIA and CP rather than as a distinct category.

The ecological validity of delay aversion and response inhibition as measures of impulsivity in AD/HD: a supplement to the NIMH multimodal treatment study of AD/HD

Impulsivity is a primary symptom of the combined type of Attention Deficit/Hyperactivity Disorder (AD/HD). The Stop Signal Paradigm is premised upon a primary deficit in inhibitory control in AD/HD, whereas the Delay Aversion Hypothesis, by contrast, conceptualizes impulsivity in AD/HD, not as an inability to inhibit a response, but rather as a choice to avoid delay. This study compared the ecological validity of the Stop Signal Task (SST) and Choice-Delay Task (C-DT) measure of delay aversion, with respect to their relative utility in discriminating AD/HD children from normal control participants, and their correlations with classroom observations and with ratings of impulsivity and other core AD/HD symptoms on the Conners and SNAP-IV checklists. The tasks exhibited modest discriminant validity when used individually and excellent discriminant validity when used in combination. The C-DT correlated with teacher ratings of impulsivity, hyperactivity, and conduct problems, and with observations of gross motor activity, physical aggression, and an AD/HD composite score. The SST correlated with the observations only. These results suggest that delay aversion is associated with a broad range of AD/HD characteristics whereas inhibitory failure seems to tap a more discrete dimension of executive control.

Temporal Allocation of Visual Attention in Adult Attention Deficit Hyperactivity Disorder

In two experiments, we examined the ability of adults with attention deficit hyperactivity disorder (ADHD) to preocess multiple targets appearing in a rapid serial visual presentation (RSVP) stream. Using a standard attentional blink (AB) task, subjects were required to both identify a target in the RSVP stream and detect a probe appearing in one of several posttarget serial positions. In Experiment 1, ADHD adults exhibited a protracted AB compared to controls, in that their probe detection did not improve as a function of increasing probe-to-target intervals (450-720 msec). In Experiment 2, the ADHD group performed as well as controls in detectin probes appearing immediately (i.e., 90 msec) after the target. Taken together, the results demonstrate that adults with ADHD exhibit a selective deficit in rapidly shifting attention between the target and the probe, when two appear several hundred milliseconds apart. These results suggest that adults with ADHD can use automatic (reflexive) attention to detect items in close temporal proximity in the RSVP stream, but have difficulty allocating controlled attention to multiple stimuli separated by several hundred milliseconds.

Analogue assessment of child behavior problems

The psychometric properties of analogue assessment measures of child behavior problems are reviewed. Analogue assessment refers to an observational measure of targeted behaviors that are elicited by simulated experimental conditions, which, in turn, are devised to approximate natural circumstances. For the most part, this assessment approach has been used sporadically in the clinical setting with children who are behaviorally disturbed. Lack of standardization of measures and inconsistent findings of ecological validity are among several concerns noted. The paucity of available data limits conclusions that can be drawn at this time about the role of analogue assessment in the evaluation and treatment of child behavior problems.

Clinical applications of analogue behavioral observation: dimensions of psychometric evaluation

Clinical assessment applications of analogue behavioral observation are discussed in the context of psychometric principles. Analogue behavioral observation involves the measurement of a client's overt behavior in a contrived situation that is analogous to situations that the client is likely to encounter in his or her natural environment. The goal of analogue behavioral observation is to derive valid estimates of the client's behavior in a current or future natural environment. Analogue behavioral observation instruments are often developed with insufficient attention to their psychometric properties, particularly content validity. Psychometric evaluative dimensions vary in their importance, as a function of the goals of the assessment. Although analogue behavioral observation instruments can be sensitive to change, their validity can erode over time and is affected by numerous sources of variance. Analogue behavioral observation assessment may be especially useful in detecting important functional relations in clinical assessment.

A comparison of the cognitive deficits in reading disability and attention-deficit/hyperactivity disorder

This study used a nonreferred sample of twins to contrast the performance of individuals with reading disability (RD; n = 93), attention-deficit/hyperactivity disorder (ADHD; n = 52), RD and ADHD (n = 48), and neither RD nor ADHD (n = 121) on measures of phoneme awareness (PA) and executive functioning (EF). Exploratory factor analysis of the EF measures yielded underlying factors of working memory, inhibition, and set shifting. Results revealed that ADHD was associated with inhibition deficits, whereas RD was associated with significant deficits on measures of PA and verbal working memory. The RD + ADHD group was most impaired on virtually all measures, providing evidence against the phenocopy hypothesis as an explanation for comorbidity between RD and ADHD.

Upgrading the science and technology of assessment and diagnosis: laboratory and clinic-based assessment of children with ADHD

Reviews the usefulness of clinic-based and laboratory-based instruments and paradigms for diagnosing attention deficit hyperactivity disorder (ADHD) and monitoring treatment effects. Extant literature examining the performance of normal children and those with ADHD on an extensive range of neurocognitive tests, tasks, and experimental paradigms indicates that particular types of instruments may be more reliable than others with respect to detecting between-group differences. We review task parameters that may distinguish the more reliable from less reliable instruments. The value of clinic-based and laboratory-based instruments for monitoring treatment response in children with ADHD is questionable when evaluated in the context of ecologically relevant variables such as classroom behavior and academic functioning. We present a general conceptual model to highlight conceptual issues relevant to designing clinic-based and laboratory-based instruments for the purposes of diagnosing and monitoring treatment effects in children with ADHD. Application of the model to currently conceptualized core variables indicates that attention and impulsivity-hyperactivity may represent correlative rather than core features of the disorder. We discuss implications of these findings for designing the next generation of clinic-based and laboratory-based instruments.

Does the Conners' Continuous Performance Test aid in ADHD diagnosis?

The performance of clinic-referred children aged 6-11 (N = 100) was examined using the Conners' Continuous Performance Test (CPT) and measures of auditory attention (Auditory Continuous Performance Test; ACPT), phonological awareness, visual processing speed, and visual-motor competence. The Conners' CPT overall index was unrelated to measures of visual processing speed or visual-motor competence. Although the Conners' CPT converged with the ACPT, the latter demonstrated age and order effects. Significant variance in Conners' CPT parameters was predicted by phonological awareness measures, suggesting that Reading Disordered (RD) children could be "false positives" on the Conners' CPT. The Conners' CPT overall index, phonological awareness, and visual-motor measures were submitted to a 2 x 2 MANCOVA (ADHD vs. RD, covarying for age and socioeconomic status): a main effect for RD status was found. Children with ADHD did not have higher Conners' CPT scores than did clinical controls; however, children with Reading Disorders did. Phonological measures distinguished RD children from ADHD children and other clinical controls. ADHD children who failed the Conners' CPT were rated by teachers as more hyperactive. Despite the strengths of the Conners' CPT, its utility for differential diagnosis of ADHD is questioned.

Learning disabilities and ADHD: overlapping spectrumn disorders

Clinical and psychoeducational data were analyzed for 119 children ages 8 to 16 years who were evaluated in a child diagnostic clinic. A learning disability (LD) was present in 70% of the children with attention-deficit/hyperactivity disorder (ADHD), with a learning disability in written expression two times more common (65%) than a learning disability in reading, math, or spelling. Children with LD and ADHD had more severe learning problems than children who had LD but no ADHD, and the former also had more severe attention problems than children who had ADHD but no LD. Further, children with ADHD but no LD had some degree of learning problem, and children with LD but no ADHD had some degree of attention problem. Results suggest that learning and attention problems are on a continuum, are interrelated, and usually coexist.

Klinische Validität der computerunterstützten TAP bei Kindern mit Aufmerksamkeits-/Hyperaktivitätsstörungen

Zusammenfassung: Die Studie diente der klinischen Validierung der Testbatterie zur Aufmerksamkeitsprüfung (TAP) bei Kindern mit Aufmerksamkeits-/Hyperaktivitätsstörungen. Die Stichprobe bestand aus 20 Jungen mit Aufmerksamkeits-/Hyperaktivitätsstörungen und 20 männlichen Kontrollkindern im Alter von 7;5-13;5 Jahren. Die beiden Gruppen wurden bezüglich spezifischer und allgemeiner Aufmerksamkeitsfunktionen verglichen. Allgemein zeigte die Gruppe der Kinder mit Aufmerksamkeits-/Hyperaktivitätsstörungen im Vergleich zur Kontrollgruppe mehr Fehler und Auslassungen und erhöhte intraindividuelle Streuungen der Reaktionszeiten in verschiedenen Subtests. Die Untersuchung der diskriminativen Validität der TAP-Tests ergab, dass durch zwei Testmaße und unter Berücksichtigung des Testalters 90 % der Kinder beider Gruppen richtig klassifiziert werden konnten. Ein spezifisches Aufmerksamkeitsdefizit der Kinder mit Aufmerksamkeits-/Hyperaktivitätsstörungen wurde nur in einem Subtest, in dem das Tempo der Reizdarbietung nicht vorgegeben war, d. h. in einer zeitlich wenig strukturierten Aufgabe, festgestellt. Die Untersuchung spricht für die klinische Validität der TAP-Testbatterie zur Untersuchung von Kindern mit Aufmerksamkeits-/Hyperaktivitätsstörungen.

A follow-up pilot study of objective measures in children with attention deficit hyperactivity disorder

OBJECTIVES

Attention deficit hyperactivity disorder (ADHD) is a common childhood problem requiring stimulant medications in a significant proportion of cases. The aim of this pilot study was to assess the effects of prolonged stimulant medication therapy on a continuous performance test, the Test of Variables of Attention (TOVA), which measures objectively features of ADHD.

METHODS

Eighteen children aged 8 to 16 years who were diagnosed with ADHD, based on the Diagnostic and Statistical Manual of Mental Disorders 4th edn criteria, were included in the study. Assessment on a continuous performance test (TOVA) was performed initially and the children were administered stimulant medications for at least 12 months. The medications were stopped for 1 week, followed by a repeat TOVA assessment which was compared to the initial TOVA assessment.

RESULTS

Follow up TOVA scores showed a significant improvement in mean commission errors (impulsivity) after the stimulant medication therapy. No significant improvement was found in omission errors (inattention), response time and variability. There was a significant positive correlation between commission and omission scores (P value 0.0001).

CONCLUSIONS

The results of this pilot study indicate that there is objective improvement in impulsivity in children with ADHD after a prolonged period of stimulant medication therapy. The study suggests that it would be useful to perform formal studies to investigate this further and also to assess the role of continuous performance test (TOVA) as a method for monitoring the need for ongoing therapy.

Assessment in multisite randomized clinical trials of patients with autistic disorder: the Autism RUPP Network. Research Units on Pediatric Psychopharmacology

Assessment of autistic disorder (autism) symptoms, primary and secondary, poses more challenging problems than ordinarily found in multisite randomized clinical trial (RCT) assessments. For example, subjects may be uncommunicative and extremely heterogeneous in problem presentation, and current pharmacological treatments are not likely to alter most core features of autism. The Autism Research Units on Pediatric Psychopharmacology (RUPP Autism Network) resolved some of these problems during the design of a risperidone RCT in children/adolescents. The inappropriateness of the usual anchors for a Clinical Global Impression of Severity (CGI-S) was resolved by defining uncomplicated autism without secondary symptoms as a CGI-S of 3, mildly ill. The communication problems, compromising use of the patient as an informant, were addressed by several strategies, including careful questioning of care providers, rating scales, laboratory tests, and physical exams. The broad subject heterogeneity requires outcome measures sensitive to individual change over a wide spectrum of treatment response and side effects. The problems of neuropsychologically testing nonverbal, lower functioning, sometimes noncompliant subjects requires careful instrument selection/adaptation and flexible administration techniques. The problems of assessing low-end IQs, neglected by most standardized test developers, was resolved by an algorithm of test hierarchy. Scarcity of other autism-adapted cognitive and neuropsychological tests and lack of standardization required development of a new, specially adapted battery. Reliability on the Autism Diagnostic Interview (currently the most valid diagnostic instrument) and other clinician instruments required extensive cross-site training (in-person, videotape, and teleconference sessions). Definition of a treatment responder required focus on individually relevant target symptoms, synthesis of possible modest improvements in many domains, and acceptance of attainable though imperfect goals. The assessment strategy developed is implemented in a RCT of risperidone (McDougle et al., 2000) for which the design and other methodological challenges are described elsewhere (Scahill et al., 2000). Some of these problems and solutions are partially shared with RCTs of other treatments and other disorders.

Effects of methylphenidate on sensitivity to reinforcement in children diagnosed with attention deficit hyperactivity disorder: an application of the matching law

The behavior of children diagnosed with attention deficit hyperactivity disorder (ADHD) has been hypothesized to be the result of decreased sensitivity to consequences compared to typical children. The present study examined sensitivity to reinforcement in 2 boys diagnosed with ADHD using the matching law to provide more precise and quantitative measurement of this construct. This experiment also evaluated the effects of methylphenidate (MPH) on sensitivity to reinforcement of children with ADHD. Subjects completed math problems to earn tokens under four different variable-interval (VI) schedules of reinforcement presented in random order under both medicated and nonmedicated conditions. Results showed that, in the medicated condition, the matching functions for both subjects resulted in higher asymptotic values, indicating an overall elevation of behavior rate under these conditions. The variance accounted for by the matching law was also higher under the medicated conditions, suggesting that their behavior more closely tracked the changing rates of reinforcement while taking MPH compared to placebo. Under medicated conditions, the reinforcing efficacy of response-contingent tokens decreased. Results are discussed with respect to quantifying behavioral changes and the extent to which the drug interacts with prevailing contingencies (i.e., schedule values) to influence behavioral variability.

Relations of age to cognitive and motivational elements of impulse control in boys with and without externalizing behavior problems

In a cross-sectional study of 83 unmedicated boys, 6 to 16 years of age (M = 10.6, SD = 2.1), attending public (N = 48) and therapeutic schools for behaviorally disturbed children (N = 35), we examined relations of externalizing psychopathology to age-dependent change in performance on cognitive and motivational dimensions of impulse control assessed by laboratory tasks. When we controlled for internalizing symptoms and IQ or school achievement, all children showed improving competence with increasing age on both dimensions over the age range of the sample. Children with externalizing problems performed more poorly on both dimensions at all ages than children without such problems. Comparing age-dependent competence for the two groups, a model of convergent maturation in cognitive aspects of impulse control, and a model depicting a stable deficit in motivational aspects of impulse control in those children with externalizing behavior problems, relative to those without such problems, emerged. Studies of individual growth in impulse control, together with correlates of growth, are needed to validate these observations.