Jaap Oosterlaan

Response inhibition in AD/HD, CD, comorbid AD/HD + CD, anxious, and control children : A meta-analysis of studies with the stop task

The aim of this study was to investigate whether impaired response inhibition is uniquely related to AD/HD or whether deficits in response inhibition are also evident in other psychopathological disorders. Furthermore, the suggestion was examined that anxiety disorders are associated with abnormally high levels of response inhibition. This paper presents the results of a meta-analysis of eight studies in which response inhibition was assessed with the so-called stop task in five groups of children: children with attention deficit/hyperactivity disorder (AD/HD), children with conduct disorder (CD), children with AD/HD + CD, children with anxiety disorders, and control children. A total of 456 children participated in the 8 studies. All children were in the age range 6-12 years. Consistent and robust evidence was found for a response inhibition deficit in AD/HD. However, response inhibition deficits did not distinguish children with AD/HD from children with CD, nor from children with comorbid AD/HD + CD. Contrary to predictions, anxious children did not demonstrate enhanced levels of response inhibition.

Psychological Mechanisms in Hyperactivity: I Response Inhibition Deficit, Working Memory Impairment, Delay Aversion, or Something Else?

This study tested the predictions of three different theories of hyperactivity: response inhibition deficit, working memory impairment, and delay aversion. A sample of 51 pervasively hyperactive children and 119 control children, identified by screening a general population sample of 1,316 twin pairs, were assessed on tests relating to each of these theories. The hyperactive group performed worse than the control group on the delay aversion measure and some of the working memory tasks. Controlling for IQ removed the significant group differences on the working memory measures, however. There were no significant group differences on the inhibition variables derived from the stop task. However, there was evidence of a pattern of responding on the stop task that was strongly characteristic of hyperactivity: hyperactive children were variable in their speed, generally slow and inaccurate in responding. This pattern of responses may indicate a nonoptimal effort/ activation state. Hyperactive girls were indistinguishable from hyperactive boys in their performance on the tasks.

Information processing and energetic factors in attention deficit hyperactivity disorder

Currently, children and adolescents with an excess of hyperactive, inattentive, and impulsive behavior are diagnosed as Attention-Deficit/ Hyperactivity Disorder (ADHD; see the Diagnostic and Statistical Manual of Mental Disorders {DSM-IV}, American Psychiatric Association, 1994, and chapter 1, this volume).

Inhibition in ADHD, aggressive, and anxious children: A biologically based model of child psychopathology

In this study the stop signal task was employed to investigate inhibitory control in 15 children with attention deficit hyperactivity disorder (ADHD), 18 aggressive and 20 anxious children, and a group of 17 normal controls. The psychopathological groups were recruited from special educational services. Parent, teacher, and child questionnaires were used to select children with pervasive disorders. Controls attended regular classes and scored low on all questionnaires. Based on Quays model of child psychopathology (Quay, 1988, 1993), we hypothesized a deficit in inhibitory control in children with externalizing disorders, whereas anxious children were predicted to be overinhibited. The ADHD group and the aggressive group showed poor inhibitory control and a slower inhibitory process. No evidence of overinhibition was found in anxious children.

High antenatal maternal anxiety is related to impulsivity during performance on cognitive tasks in 14- and 15-year-olds

This study prospectively investigated the influence of antenatal maternal anxiety, measured with the State Trait Anxiety Inventory at 12-22, 23-31 and 32-40 postmenstrual weeks of pregnancy, on cognitive functioning in 57 adolescents (mean age 15 years). ANCOVAs showed effects of State anxiety at 12-22 weeks, after controlling for influences of State anxiety in later pregnancy and postnatal maternal Trait anxiety. Adolescents of high anxious pregnant women reacted impulsively in the Encoding task; they responded faster but made more errors than adolescents of low anxious women. They also scored lower on two administered WISC-R subtests. In the Stop task no differences in inhibiting ongoing responses were found between adolescents of high and low anxious pregnant women. We suspect that high maternal anxiety in the first half of pregnancy may negatively affect brain development of the fetus, reflected by impulsivity and lower WISC-R scores at 14-15 years.

Response inhibition and response re-engagement in attention-deficit/hyperactivity disorder, disruptive, anxious and normal children.

The purpose of this study was to determine whether attention-deficit/hyperactivity disorder (AD/HD) is uniquely related to impairments in two aspects of executive functioning: (1) response inhibition: and (2) response re-engagement. AD/HD (n = 10), disruptive (n = 11), anxious (n = 11) and normal children (n = 21) were compared on the change task. Children were in the age range of 8 12 years. The psychopathological groups were recruited from special educational services. Parent, teacher and child questionnaires were used to select children with pervasive disorders. Controls attended normal classes and scored low on all questionnaires. Compared with normal children, both AD/HD and disruptive children showed poor response inhibition, but only AD/HD children exhibited a deficit in the underlying inhibitory process. Some evidence was found for enhanced response inhibition in anxious children. Both AD/HD and disruptive children demonstrated higher variability in the speed of the response re-engagement process and were less accurate. The results suggest that AD/HD involves a more pervasive impairment in cognitive functioning, rather than a deficit restricted to the powers of response inhibition.

Inhibitory dysfunction in hyperactive boys

Recent evidence suggests that the main deficit in childhood hyperactivity is in frontal lobe-mediated self-regulative functions such as inhibitory control. Hyperactives have consistently been shown to perform poorly on the stop task, which is a laboratory measurement of inhibitory control. This study was aimed at extending knowledge about inhibitory processes involved in the hyperactives performance on this task. For this purpose, the performance of 11 pervasive hyperactives was compared to the performance of normal children on two stop tasks which differed from each other in the contingency of timing of the stop signal. In Stop1 stop signals were internally related, i.e. presented at time intervals after onset of the response stimulus, whereas in Stop2 stop signals were externally related, i.e. presented at time intervals related to the subjects own go-process. Both tasks were modifications of the classical stop task in modality of the stop signal visual instead of auditory and in event rate, which was half-shortened. The aim of this study was: (a) to replicate the findings of deficient inhibitory functions in hyperactive children in the stop task in spite of modifications in modality and event rate; and (b) to elucidate (dis)similarities of stopping processes or of group differences in these stopping processes triggered by stop delays related either to external or to internal processes. Hyperactive children were less efficient than controls in inhibiting their motor response in both versions of the stop task. independent of whether the stop signals were externally or internally related. Furthermore, the go-process of the hyperactives was more variable and erratic in both tasks. Thus, the results strengthen the effectiveness of stop tasks in distinguishing hyperactive from normal children.

Effects of Reward and Response Cost on Response Inhibition in AD/HD, Disruptive, Anxious, and Normal Children

In previous research, children with attention deficit/hyperactivity disorder (AD/HD) have demonstrated impaired response inhibition on the stop paradigm. In this study we examined whether this impairment in fact reflects a motivational deficit. Four groups of children (age range 7–13 years) participated in the study: 14 AD/HD children, 21 normal controls, 14 disruptive children, and 14 anxious children. The psychopathological groups were recruited from special educational services and mental health outpatient clinics. Parent, teacher, and child questionnaires were used to select children with pervasive disorders. Normal controls attended regular classes and scored low on all questionnaires. Children were tested once with reward contingencies and once with response cost contingencies in a randomized cross-over design. We hypothesized that if a motivational deficit underlies poor response inhibition in AD/HD children, this deficit will be remedied by response contingencies. Despite the presence of response contingencies, AD/HD children showed poor response inhibition compared with normal controls. Findings argue against a motivational explanation for the response inhibition deficit in AD/HD children

Syndrome dimensions of the Child Behavior Checklist and the Teacher Report Form : A critical empirical evaluation

The construct representation of the cross-informant model of the Child Behavior Checklist (CBCL) and the Teacher Report Form (TRF) was evaluated using confirmatory factor analysis. Samples were collected in seven different countries. The results are based on 13,226 parent ratings and 8893 teacher ratings. The adequacy of fit for the cross-informant model was established on the basis of three approaches: conventional rules of fit, simulation, and comparison with other models. The results indicated that the cross-informant model fits these data poorly. These results were consistent across countries, informants, and both clinical and population samples. Since inadequate empirical support for the cross-informant syndromes and their differentiation was found, the construct validity of these syndrome dimensions is questioned.

Contrasting deficits on executive functions between ADHD and Reading Disabled children

BACKGROUNDnThe object of this study was to analyze the executive functioning of children with attention deficit hyperactivity disorder (ADHD) or reading disability (RD) independent of their non-executive deficits.nnnMETHODSnThree carefully diagnosed groups of children, aged between 7 and 12 years (35 ADHD, 22 RD and 30 typically developing children), were tested on a wide range of tasks related to five major domains of executive functioning (EF): inhibition, visual working memory, planning, cognitive flexibility, and verbal fluency. Additional tasks were selected for each domain to control for non-executive processing.nnnRESULTSnADHD children were impaired on interference control, but not on prepotent and ongoing response suppression. ADHD showed deficits on visual working memory, planning, cognitive flexibility and phonetic fluency. RD children were impaired on phonetic fluency. The only EF measure that differentiated ADHD from RD was planning.nnnCONCLUSIONSnThe present sample of ADHD children showed several EF deficits, whereas RD children were almost spared executive dysfunction, but exhibited deficits in phonetic fluency.