The influence of very preterm birth on adolescent EEG connectivity, network organization and long-term outcome

OBJECTIVE

The aim of this study was to explore differences in functional connectivity and network organization between very preterm born adolescents and term born controls and to investigate if these differences might explain the relation between preterm birth and adverse long-term outcome.

METHODS

Forty-seven very preterm born adolescents (53% males) and 54 controls (54% males) with matching age, sex and parental educational levels underwent high-density electroencephalography (EEG) at 13 years of age. Long-term outcome was assessed by Intelligence Quotient (IQ), motor, attentional functioning and academic performance. Two minutes of EEG data were analysed within delta, theta, lower alpha, upper alpha and beta frequency bands. Within each frequency band, connectivity was assessed using the Phase Lag Index (PLI) and Amplitude Envelope Correlation, corrected for volume conduction (AEC-c). Brain networks were constructed using the minimum spanning tree method.

RESULTS

Very preterm born adolescents had stronger beta PLI connectivity and less differentiated network organization. Beta AEC-c and differentiation of AEC-c based networks were negatively associated with long-term outcomes. EEG measures did not mediate the relation between preterm birth and outcomes.

CONCLUSIONS

This study shows that very preterm born adolescents may have altered functional connectivity and brain network organization in the beta frequency band. Alterations in measures of functional connectivity and network topologies, especially its differentiating characteristics, were associated with neurodevelopmental functioning.

SIGNIFICANCE

The findings indicate that EEG connectivity and network analysis is a promising tool for investigating underlying mechanisms of impaired functioning.

Heterogeneity of persisting symptoms after sport-related concussion (SRC): exploring symptom subtypes and patient subgroups

This study aimed to explore the heterogeneity of persisting symptoms after sport-related concussion (SRC). We examined the structure of symptom subtypes within 163 patients with SRC (M = 16.7 weeks post-injury). Subsequently, we investigated the existence of subgroups of patients based on comparable configuration of co-occurring symptom subtypes. To explore factors that may contribute to the emergence of SRC patient subgroups, subgroups were compared on pre-injury (i.e., demographics and medical history), personality (Severity Indices of Personality Problems Short Form) and SRC characteristics (i.e., history of prior concussions, loss of consciousness and post-traumatic amnesia). To investigate the relevance of SRC subgrouping for clinical outcome, subgroups were compared on symptom severity (Sport Concussion Assessment Tool 5). The results provide empirical evidence for the existence of symptom subtypes, characterized as a: neurocognitive, fatigue, emotional, migraine and vestibular-ocular symptom subtype in patients with persisting SRC. Study results also showed evidence for the existence of SRC subgroups of patients with a comparable configuration of co-occurring prevailing symptom subtypes, including a neurocognitive-migraine, fatigue, migraine-emotional and neurocognitive-emotional subgroup. The subgroups differed on pre-injury, personality and SRC characteristics, suggesting that these factors may contribute to the emergence of specific SRC patient subgroups. The subgroups also differed in the severity of persisting symptoms, highlighting the clinical relevance of SRC subgrouping. These results support the idea that patient subgroups with persisting SRC with a comparable pattern of co-occurring symptom subtypes exists, which may require targeted prognosis, clinical management and treatment to optimize recovery.

Distress and post-traumatic stress in parents of patients with congenital gastrointestinal malformations: a cross-sectional cohort study

Background

Congenital gastrointestinal malformation (CGIM) require neonatal surgical treatment and may lead to disease-specific sequelae, which have a potential psychological impact on parents. The aim of this study is to assess distress and symptoms of post-traumatic stress disorder (PTSD) in parents of patients with CGIM. In this cross-sectional study, seventy-nine parents (47 mothers and 32 fathers) of 53 patients with CGIM completed the Distress Thermometer for Parents (DT-P) and the Self Rating Scale for Posttraumatic Stress Disorders (SRS-PTSD) as part of the multidisciplinary follow-up of their children (aged 5–35 months). Group differences were tested between parents and representative Dutch reference groups with regard to rates of (clinical) distress and PTSD, and severity of overall distress and PTSD, for mothers and fathers separately. Mixed model regression models were used to study factors associated with the risk of (clinical) distress, PTSD and with severity of symptoms of PTSD (intrusion, avoidance and hyperarousal).

Results

Prevalence of clinical distress was comparable to reference groups for mothers (46%) and fathers (34%). There was no difference in severity of overall distress between both mothers as well as fathers and reference groups. Prevalence of PTSD was significantly higher in mothers (23%) compared to the reference group (5.3%) (OR = 5.51, p < 0.001), not in fathers (6.3% vs 2.2.%). Symptoms of intrusion were commonly reported by all the parents (75%). Longer total length of child’s hospital stay was associated with more severe symptoms of intrusion, avoidance and hyperarousal. Child’s length of follow-up was negatively associated with severity of intrusion.

Conclusions

Having a child with CGIM has a huge impact on parents, demonstrated by a higher prevalence of PTSD in mothers, but not fathers, compared to parents in the general population. Monitoring of symptoms of PTSD of parents in follow-up is necessary.

Differential effects of long-term aerobic versus cognitively-engaging physical activity on children's visuospatial working memory related brain activation: A cluster RCT

Different types of physical activity are thought to differentially affect children's brain activation, via physiological mechanisms, or by activating similar brain areas during physical and cognitive tasks. Despite many behavioral studies relying on these mechanisms, they have been rarely studied. This study looks at both mechanisms simultaneously, by examining effects of two physical activity interventions (aerobic vs. cognitively-engaging) on children's brain activation. Functional Magnetic Resonance Imaging (fMRI) data of 62 children (48.4% boys, mean age 9.2 years) was analyzed. Children's visuospatial working memory related brain activity patterns were tested using a Spatial Span Task before and after the 14-week interventions consisting of four physical education lessons per week. The control group followed their regular program of two lessons per week. Analyses of activation patterns in SPM 12.0 revealed no activation changes between pretest and posttest (p > .05), and no differences between the three conditions in pretest-posttest changes in brain activation (p > .05). Large inter-individual differences were found, suggesting that not every child benefited from the interventions in the same way. To get more insight into the assumed mechanisms, further research is needed to understand whether, when, for whom, and how physical activity results in changed brain activation patterns.

Relationships between gross motor skills, cardiovascular fitness, and visuospatial working memory-related brain activation in 8- to 10-year-old children

Relationships between gross motor skills and cardiovascular fitness with visuospatial working memory (VSWM) in children are hypothesized to be mediated by underlying functional brain mechanisms. Because there is little experimental evidence to support this mechanism, the present study was designed to investigate the relationships of gross motor skills and cardiovascular fitness with VSWM-related brain activation in 8- to 10-year-old children. Functional magnetic resonance imaging data obtained during a VSWM-task were analyzed for 80 children from grades 3 (47.5%) and 4 of 21 primary schools in the Netherlands (51.3% girls). Gross motor skills (Korper Koordinationstest für Kinder and Bruininks-Oseretsky Test of Motor Proficiency - 2nd Edition) and cardiovascular fitness (20-meter Shuttle Run Test) were assessed. VSWM-related brain activation was found in a network involving the angular gyrus, the superior parietal cortex, and the thalamus; deactivation was found in the inferior and middle temporal gyri. Although behavioral results showed significant relations of gross motor skills and cardiovascular fitness with VSWM performance, gross motor skills and cardiovascular fitness were not related to VSWM-related brain activation. Therefore, we could not confirm the hypothesis that brain activation underlies the relationship of gross motor skills and cardiovascular fitness with VSWM performance. Our results suggest that either the effects of physical activity on cognition do not necessarily go via changes in gross motor skills and/or cardiovascular fitness, or that brain activation patterns as measured with the blood-oxygen-level dependent (BOLD) signal may not be the mechanism underlying the relationships of gross motor skills and cardiovascular fitness with VSWM.

Role of conduct problems in the relation between Attention-Deficit Hyperactivity disorder, substance use, and gaming

Known comorbidities for Attention-Deficit Hyperactivity Disorder (ADHD) include conduct problems, substance use disorder and gaming. Comorbidity with conduct problems may increase the risk for substance use disorder and gaming in individuals with ADHD. The aim of the study was to build a causal model of the relationships between ADHD and comorbid conduct problems, and alcohol, nicotine, and other substance use, and gaming habits, while accounting for age and sex. We used a state-of-the-art causal discovery algorithm to analyze a case-only sample of 362 ADHD-diagnosed individuals in the ages 12-24 years. We found that conduct problem severity mediates between ADHD severity and nicotine use, but not with more severe alcohol or substance use. More severe ADHD-inattentive symptoms lead to more severe gaming habits. Furthermore, our model suggests that ADHD severity has no influence on severity of alcohol or other drug use. Our findings suggest that ADHD severity is a risk factor for nicotine use, and that this effect is fully mediated by conduct problem severity. Finally, ADHD-inattentive severity was a risk factor for gaming, suggesting that gaming dependence has a different causal pathway than substance dependence and should be treated differently. By identifying these intervention points, our model can aid both researchers and clinicians.

Multilingualism was associated with lower cognitive outcomes in children who were born very and extremely preterm

Aim

This study determined whether cognitive outcomes differed between very preterm (VPT) and extremely preterm (EPT) children who were monolingual or multilingual when they reached the corrected ages of two and five years.

Methods

The data were collected at the Emma Children's Hospital, Amsterdam, The Netherlands, as part of our national neonatal follow‐up programme and comprised 325 VPT/EPT children born between January 1, 2007 and January 1, 2012. The study used the Third Editions of the Bayley Scales of Infant and Toddler Development and the Wechsler Preschool and Primary Scale of Intelligence.

Results

We compared 234 monolingual children, 65 multilingual children who spoke Dutch and at least one foreign language at home and 26 multilingual children who didn't speak Dutch at home. The best performers on the cognitive scale at two years of age and the verbal subscales at five years of age were the monolingual children, followed by the children who spoke Dutch and at least one foreign language at home, then the children who only spoke foreign languages at home.

Conclusion

In our study cohort from The Netherlands, multilingualism lowered the cognitive and verbal outcomes of VPT/EPT children at the corrected ages of two and five years.

Long-term outcome and quality of life in patients with total colonic aganglionosis in the Netherlands

AIM

Total colonic aganglionosis (TCA) is a severe form of Hirschsprung's disease (HD) associated with a high morbidity. This study assessed long-term functional outcome and quality of life (QoL) of patients with TCA in a national consecutive cohort.

METHODS

Surgical and demographic characteristics in the medical records of all patients (n = 53) diagnosed with TCA between 1995 and 2015 were reviewed. Functional outcome of all nonsyndromal patients, aged ≥ 4 years (n = 35), was assessed using a questionnaire and in medical records. Generic and disease-specific QoL were assessed using standardized validated questionnaires.

RESULTS

Of 35 patients eligible for follow-up, 18 (51%) responded to the questionnaires. They were aged 4-19 years. A Duhamel procedure was performed in 67% of these patients and a Rehbein procedure was performed in 33%. In the questionnaire, 65% of the patients reported constipation, 47% faecal incontinence and 53% soiling. Moreover, 18% of patients used bowel management (flushing or laxatives) and 29% had an adapted diet only. Children and adolescents with TCA had worse perception of their general health and were more limited by bodily pain and discomfort compared with healthy peers. Their quality of life is influenced most by frequent complaints of diarrhoea and other physical symptoms.

CONCLUSION

Children and adolescents with TCA report lower health-related QoL compared with healthy peers, especially in the physical domain. We suggest standardized follow-up and prospective longitudinal future research on functionality and QoL of these patients.

Very preterm born children at early school age: Healthcare therapies and educational provisions

AIM

To explore changes in motor and cognitive outcomes in very preterm (VP; gestational age<30weeks) born children between ages five and six years, and to determine whether changes in these outcomes were associated with the use of healthcare therapies and educational provisions.

STUDY DESIGN

Single-center observational cohort study. Five-year-old VP born children of a one-year-cohort of our neonatal follow-up program (N=90) were invited for re-assessments at age six. Use of healthcare therapies and educational provisions was registered at ages five and six years. Motor function (Movement Assessment Battery for Children-2 [M-ABC-2]; higher scores indicate better functioning) and IQ (Wechsler Preschool and Primary Scale for Intelligence [WPPSI-III-NL]) were assessed at both ages.

RESULTS

Sixty-four VP born children were seen at ages five and at six years. In this year, 61% received healthcare therapies and/or educational provisions. M-ABC-2 scores of VP born children who received healthcare therapy and/or educational provisions were significantly higher (M=8.9 [SD=3.2]) at age six years than at age five years (M=7.5 [SD=3.3]); p<0.00). M-ABC-2 scores remained stable in the average range in VP born children without any support. IQ scores remained stable irrespective of received support.

CONCLUSIONS

Improvements in motor outcomes are associated with the use of healthcare therapies and/or educational support between ages five and six years in VP born children. Future studies need to determine the efficacy of existing interventions, and to develop tailored interventions to support VP born children in the transfer period from preschool to primary education.

The association between the behavior rating inventory of executive functioning and cognitive testing in children diagnosed with a brain tumor

Pediatric brain tumor survivors (PBTS) suffer from cognitive late effects, such as deteriorating executive functioning (EF). We explored the suitability of the Behavior Rating Inventory of Executive Function (BRIEF) to screen for these late effects. We assessed the relationship between the BRIEF and EF tasks, and between the BRIEF-Parent and BRIEF-Teacher, and we explored the clinical utility. Eighty-two PBTS (8-18 years) were assessed with EF tasks measuring attention, cognitive flexibility, inhibition, visual-, and working memory (WM), and with the BRIEF-Parent and BRIEF-Teacher. Pearson's correlations between the BRIEF and EF tasks, and between the BRIEF-Parent and BRIEF-Teacher were calculated. The BRIEF-Parent related poorly to EF tasks (rs < .26, ps > .01), but of the BRIEF-Teacher the WM-scale, Monitor-scale, Behavioral-Regulation-Index, and Meta-cognition-Index, and Total-score (rs > .31, ps < .01) related significantly to some EF tasks. When controlling for age, only the WM scale and Total score related significantly to the attention task (ps < .01). The inhibit scales of the BRIEF-Parent and BRIEF-Teacher correlated significantly (r = .33, p < .01). Children with clinically elevated scores on BRIEF scales that correlated with EF tasks performed worse on all EF tasks (ds 0.56-1.23, ps < .05). The BRIEF-Teacher Total and Index scores might better screen general EF in PBTS than the BRIEF-Parent. However, the BRIEF-Teacher is also not specific enough to capture separate EFs. Solely relying on the BRIEF as a screening measure of EFs in BPTS is insufficient. Questionnaires and tasks give distinctive, valuable information.

Predicting attention-deficit/hyperactivity disorder severity from psychosocial stress and stress-response genes: a random forest regression approach

Identifying genetic variants contributing to attention-deficit/hyperactivity disorder (ADHD) is complicated by the involvement of numerous common genetic variants with small effects, interacting with each other as well as with environmental factors, such as stress exposure. Random forest regression is well suited to explore this complexity, as it allows for the analysis of many predictors simultaneously, taking into account any higher-order interactions among them. Using random forest regression, we predicted ADHD severity, measured by Conners' Parent Rating Scales, from 686 adolescents and young adults (of which 281 were diagnosed with ADHD). The analysis included 17 374 single-nucleotide polymorphisms (SNPs) across 29 genes previously linked to hypothalamic-pituitary-adrenal (HPA) axis activity, together with information on exposure to 24 individual long-term difficulties or stressful life events. The model explained 12.5% of variance in ADHD severity. The most important SNP, which also showed the strongest interaction with stress exposure, was located in a region regulating the expression of telomerase reverse transcriptase (TERT). Other high-ranking SNPs were found in or near NPSR1, ESR1, GABRA6, PER3, NR3C2 and DRD4. Chronic stressors were more influential than single, severe, life events. Top hits were partly shared with conduct problems. We conclude that random forest regression may be used to investigate how multiple genetic and environmental factors jointly contribute to ADHD. It is able to implicate novel SNPs of interest, interacting with stress exposure, and may explain inconsistent findings in ADHD genetics. This exploratory approach may be best combined with more hypothesis-driven research; top predictors and their interactions with one another should be replicated in independent samples.

Interplay between stress response genes associated with attention-deficit hyperactivity disorder and brain volume

The glucocorticoid receptor plays a pivotal role in the brain's response to stress; a haplotype of functional polymorphisms in the NR3C1 gene encoding this receptor has been associated with attention-deficit hyperactivity disorder (ADHD). The serotonin transporter (5-HTT) gene polymorphism 5-HTTLPR is known to influence the relation between stress exposure and ADHD severity, which may be partly because of its reported effects on glucocorticoid levels. We therefore investigated if NR3C1 moderates the relation of stress exposure with ADHD severity and brain structure, and the potential role of 5-HTTLPR. Neuroimaging, genetic and stress exposure questionnaire data were available for 539 adolescents and young adults participating in the multicenter ADHD cohort study NeuroIMAGE (average age: 17.2 years). We estimated the effects of genetic variation in NR3C1 and 5-HTT, stress exposure and their interactions on ADHD symptom count and gray matter volume. We found that individuals carrying the ADHD risk haplotype of NR3C1 showed significantly more positive relation between stress exposure and ADHD severity than non-carriers. This gene-environment interaction was significantly stronger for 5-HTTLPR L-allele homozygotes than for S-allele carriers. These two- and three-way interactions were reflected in the gray matter volume of the cerebellum, parahippocampal gyrus, intracalcarine cortex and angular gyrus. Our findings illustrate how genetic variation in the stress response pathway may influence the effects of stress exposure on ADHD severity and brain structure. The reported interplay between NR3C1 and 5-HTT may further explain some of the heterogeneity between studies regarding the role of these genes and hypothalamic-pituitary-adrenal axis activity in ADHD.

Feedback learning and behavior problems after pediatric traumatic brain injury

BACKGROUND

Feedback learning is essential for behavioral development. We investigated feedback learning in relation to behavior problems after pediatric traumatic brain injury (TBI).

METHOD

Children aged 6-13 years diagnosed with TBI (n = 112; 1.7 years post-injury) were compared with children with traumatic control (TC) injury (n = 52). TBI severity was defined as mild TBI without risk factors for complicated TBI (mildRF- TBI, n = 24), mild TBI with ⩾1 risk factor for complicated TBI (mildRF+ TBI, n = 51) and moderate/severe TBI (n = 37). The Probabilistic Learning Test was used to measure feedback learning, assessing the effects of inconsistent feedback on learning and generalization of learning from the learning context to novel contexts. The relation between feedback learning and behavioral functioning rated by parents and teachers was explored.

RESULTS

No evidence was found for an effect of TBI on learning from inconsistent feedback, while the moderate/severe TBI group showed impaired generalization of learning from the learning context to novel contexts (p = 0.03, d = -0.51). Furthermore, the mildRF+ TBI and moderate/severe TBI groups had higher parent and teacher ratings of internalizing problems (p's ⩽ 0.04, d's ⩾ 0.47) than the TC group, while the moderate/severe TBI group also had higher parent ratings of externalizing problems (p = 0.006, d = 0.58). Importantly, poorer generalization of learning predicted higher parent ratings of externalizing problems in children with TBI (p = 0.03, β = -0.21) and had diagnostic utility for the identification of children with TBI and clinically significant externalizing behavior problems (area under the curve = 0.77, p = 0.001).

CONCLUSIONS

Moderate/severe pediatric TBI has a negative impact on generalization of learning, which may contribute to post-injury externalizing problems.

Adolescent behavioral and neural reward sensitivity: a test of the differential susceptibility theory

Little is known about the causes of individual differences in reward sensitivity. We investigated gene-environment interactions (GxE) on behavioral and neural measures of reward sensitivity, in light of the differential susceptibility theory. This theory states that individuals carrying plasticity gene variants will be more disadvantaged in negative, but more advantaged in positive environments. Reward responses were assessed during a monetary incentive delay task in 178 participants with and 265 without attention-deficit/hyperactivity disorder (ADHD), from N=261 families. We examined interactions between variants in candidate plasticity genes (DAT1, 5-HTT and DRD4) and social environments (maternal expressed emotion and peer affiliation). HTTLPR short allele carriers showed the least reward speeding when exposed to high positive peer affiliation, but the most when faced with low positive peer affiliation or low maternal warmth. DAT1 10-repeat homozygotes displayed similar GxE patterns toward maternal warmth on general task performance. At the neural level, DRD4 7-repeat carriers showed the least striatal activation during reward anticipation when exposed to high maternal warmth, but the most when exposed to low warmth. Findings were independent of ADHD severity. Our results partially confirm the differential susceptibility theory and indicate the importance of positive social environments in reward sensitivity and general task performance for persons with specific genotypes.

The key to success in elite athletes? Explicit and implicit motor learning in youth elite and non-elite soccer players

In sports, fast and accurate execution of movements is required. It has been shown that implicitly learned movements might be less vulnerable than explicitly learned movements to stressful and fast changing circumstances that exist at the elite sports level. The present study provides insight in explicit and implicit motor learning in youth soccer players with different expertise levels. Twenty-seven youth elite soccer players and 25 non-elite soccer players (aged 10-12) performed a serial reaction time task (SRTT). In the SRTT, one of the sequences must be learned explicitly, the other was implicitly learned. No main effect of group was found for implicit and explicit learning on mean reaction time (MRT) and accuracy. However, for MRT, an interaction was found between learning condition, learning phase and group. Analyses showed no group effects for the explicit learning condition, but youth elite soccer players showed better learning in the implicit learning condition. In particular, during implicit motor learning youth elite soccer showed faster MRTs in the early learning phase and earlier reached asymptote performance in terms of MRT. Present findings may be important for sports because children with superior implicit learning abilities in early learning phases may be able to learn more (durable) motor skills in a shorter time period as compared to other children.

The influence of comorbid oppositional defiant disorder on white matter microstructure in attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) and oppositional defiant disorder (ODD) are highly comorbid disorders. ADHD has been associated with altered white matter (WM) microstructure, though the literature is inconsistent, which may be due to differences in the in- or exclusion of participants with comorbid ODD. WM abnormalities in ODD are still poorly understood, and it is unclear whether comorbid ODD in ADHD may have confounded the current ADHD literature. Diffusion Tensor Imaging (DTI) was used to compare fractional anisotropy (FA) and mean diffusivity (MD) between ADHD patients with (n = 42) and without (n = 117) comorbid ODD. All participants were between 8-25 years and groups did not differ in mean age or gender. Follow-up analyses were conducted to examine the role of antisocial behaviour (conduct problems) on FA and MD values in both groups. Comorbid ODD in ADHD was associated with lower FA in left frontotemporal WM, which appeared independent of ADHD symptoms. FA was negatively associated with antisocial behaviour in ADHD + ODD, but not in ADHD-only. Comorbid ODD is associated with WM abnormalities in individuals with ADHD, which appears to be independent of ADHD symptoms. Altered WM microstructure in comorbid ODD may play a role in inconsistencies in the current DTI literature in ADHD. Altered development of these tracts may contribute to social-emotional and cognitive problems in children with oppositional and antisocial behaviour.

Influence of DAT1 and COMT variants on neural activation during response inhibition in adolescents with attention-deficit/hyperactivity disorder and healthy controls

BACKGROUND

Impairment of response inhibition has been implicated in attention-deficit/hyperactivity disorder (ADHD). Dopamine neurotransmission has been linked to the behavioural and neural correlates of response inhibition. The current study aimed to investigate the relationship of polymorphisms in two dopamine-related genes, the catechol-O-methyltransferase gene (COMT) and the dopamine transporter gene (SLC6A3 or DAT1), with the neural and behavioural correlates of response inhibition.

METHOD

Behavioural and neural measures of response inhibition were obtained in 185 adolescents with ADHD, 111 of their unaffected siblings and 124 healthy controls (mean age 16.9 years). We investigated the association of DAT1 and COMT variants on task performance and whole-brain neural activation during response inhibition in a hypothesis-free manner. Additionally, we attempted to explain variance in previously found ADHD effects on neural activation during response inhibition using these DAT1 and COMT polymorphisms.

RESULTS

The whole-brain analyses demonstrated large-scale neural activation changes in the medial and lateral prefrontal, subcortical and parietal regions of the response inhibition network in relation to DAT1 and COMT polymorphisms. Although these neural activation changes were associated with different task performance measures, no relationship was found between DAT1 or COMT variants and ADHD, nor did variants in these genes explain variance in the effects of ADHD on neural activation.

CONCLUSIONS

These results suggest that dopamine-related genes play a role in the neurobiology of response inhibition. The limited associations between gene polymorphisms and task performance further indicate the added value of neural measures in linking genetic factors and behavioural measures.

Combined stimulant and antipsychotic treatment in adolescents with attention-deficit/hyperactivity disorder: a cross-sectional observational structural MRI study

Meta-analyses suggest normalizing effects of methylphenidate on structural fronto-striatal abnormalities in patients with attention-deficit/hyperactivity disorder (ADHD). A subgroup of patients receives atypical antipsychotics concurrent with methylphenidate. Long-term safety and efficacy of combined treatment are unknown. The current study provides an initial investigation of structural brain correlates of combined methylphenidate and antipsychotic treatment in patients with ADHD. Structural magnetic resonance imaging was obtained in 31 patients who had received combined methylphenidate and antipsychotic treatment, 31 matched patients who had received methylphenidate but not antipsychotics, and 31 healthy controls (M age 16.7 years). We analyzed between-group effects in total cortical and subcortical volume, and in seven frontal cortical and eight subcortical-limbic volumes of interest, each involved in dopaminergic neurotransmission. Patients in the combined treatment group, but not those in the methylphenidate only group, showed a reduction in total cortical volume compared to healthy controls (Cohen's d = 0.69, p < 0.004), which was apparent in most frontal volumes of interest. Further, the combined treatment group, but not the methylphenidate group, showed volume reduction in bilateral ventral diencephalon (Left Cohen's d = 0.48, p < 0.04; Right Cohen's d = 0.46, p < 0.05) and the left thalamus (Cohen's d = 0.47, p < 0.04). These findings may indicate antipsychotic treatment counteracting the normalizing effects of methylphenidate on brain structure. However, it cannot be ruled out that pre-existing clinical differences between both patient groups may have resulted in anatomical differences at the time of scanning. The absence of an untreated ADHD group hinders unequivocal interpretation and implications of our findings.

Intelligence after traumatic brain injury: meta-analysis of outcomes and prognosis

Worldwide, 54-60 million individuals sustain traumatic brain injury (TBI) each year. This meta-analysis aimed to quantify intelligence impairments after TBI and to determine the value of age and injury severity in the prognosis of TBI. An electronic database search identified 81 relevant peer-reviewed articles encompassing 3890 patients. Full-scale IQ (FSIQ), performance IQ (PIQ) and verbal IQ (VIQ) impairments were quantified (Cohen's d) for patients with mild, moderate and severe TBI in the subacute phase of recovery and the chronic phase. Meta-regressions explored prognostic values of age and injury severity measures for intelligence impairments. The results showed that, in the subacute phase, FSIQ impairments were absent for patients with mild TBI, medium-sized for patients with moderate TBI (d = -0.61, P < 0.001) and large for patients with severe TBI (d = -1.09, P < 0.001). In the chronic phase, FSIQ impairments were small for patients with mild or moderate TBI (d = -0.37 and -0.19, P ≤ 0.008) and large for patients with severe TBI (d = -0.80, P < 0.001). Adults with mild TBI had larger PIQ and VIQ impairments in the chronic phase than children (both Q ≥ 5.21, P ≤ 0.02), whilst children with severe TBI had larger FSIQ and VIQ impairments than adults (both Q ≥ 4.40, P ≤ 0.04). Glasgow Coma Scale score, duration of loss of consciousness and post-traumatic amnesia duration moderately to strongly predicted FSIQ, PIQ and VIQ impairments (0.41 ≤ r ≤ 0.82, P ≤ 0.02), but no differences in predictive value were observed. In conclusion, TBI causes persisting intelligence impairments, where children may have better recovery from mild TBI and poorer recovery from severe TBI than adults. Injury severity measures predict intelligence impairments and do not outperform one another.

Attention deficit hyperactivity disorder (ADHD) and executive functioning in affected and unaffected adolescents and their parents: challenging the endophenotype construct

BACKGROUND

The results of twin and sibling studies suggest that executive functioning is a prime candidate endophenotype in attention deficit hyperactivity disorder (ADHD). However, studies have not assessed the co-segregation of executive function (EF) deficits from parents to offspring directly, and it is unclear whether executive functioning is an ADHD endophenotype in adolescents, given the substantial changes in prefrontal lobe functioning, EF and ADHD symptoms during adolescence.

METHOD

We recruited 259 ADHD and 98 control families with an offspring average age of 17.3 years. All participants were assessed for ADHD and EF [inhibition, verbal (VWM) and visuospatial working memory (VsWM)]. Data were analysed using generalized estimating equations (GEEs).

RESULTS

Parental ADHD was associated with offspring ADHD and parental EF was associated with offspring EF but there were no cross-associations (parental ADHD was not associated with offspring EF or vice versa). Similar results were found when siblings were compared. EF deficits were only found in affected adolescents and not in their unaffected siblings or (un)affected parents.

CONCLUSIONS

The core EFs proposed to be aetiologically related to ADHD, that is working memory and inhibition, seem to be aetiologically independent of ADHD in adolescence. EF deficits documented in childhood in unaffected siblings were no longer present in adolescence, suggesting that children 'grow out' of early EF deficits. This is the first study to document ADHD and EF in a large family sample with adolescent offspring. The results suggest that, after childhood, the majority of influences on ADHD are independent from those on EF. This has potential implications for current aetiological models of causality in ADHD.

Visual perception and visual-motor integration in very preterm and/or very low birth weight children: a meta-analysis

A range of neurobehavioral impairments, including impaired visual perception and visual-motor integration, are found in very preterm born children, but reported findings show great variability. We aimed to aggregate the existing literature using meta-analysis, in order to provide robust estimates of the effect of very preterm birth on visual perceptive and visual-motor integration abilities. Very preterm born children showed deficits in visual-spatial abilities (medium to large effect sizes) but not in visual closure perception. Tests reporting broad visual perceptive indices showed inconclusive results. In addition, impaired visual-motor integration was found (medium effect size), particularly in boys compared to girls. The observed visual-spatial and visual-motor integration deficits may arise from affected occipital-parietal-frontal neural circuitries.

Association between impulsivity, reward responsiveness and body mass index in children

BACKGROUND

Childhood obesity is a major health problem. An association between children's body mass index (BMI) and overeating has been established, but mechanisms leading to overeating are poorly understood. The personality characteristics impulsivity and reward responsiveness may be involved in the tendency to overeat. Impulsivity might relate to overeating through poor inhibition of food intake; reward responsiveness through the rewarding value of food.

OBJECTIVE

This study aimed to reveal the relationships between impulsivity, reward responsiveness, overeating and BMI in a sample of 346 Dutch children aged 6-13 years. The BMI distribution in the sample was representative of the BMI distribution in the Dutch pediatric population.

METHODS

Impulsivity and reward responsiveness were measured with the Dutch version of the parent-report Sensitivity to Punishment and Sensitivity to Reward Questionnaire for children. Overeating was assessed with the Dutch translation of the parent-report Children's Eating Behaviour Questionnaire.

RESULTS

Overeating, impulsivity and reward responsiveness were significantly associated with childhood BMI. Mediation analysis revealed that impulsivity and reward responsiveness equally and significantly predicted BMI indirectly through overeating.

CONCLUSIONS

The personality characteristics impulsivity and reward responsiveness predict childhood BMI indirectly through overeating. This suggests that these personality characteristics are risk factors for obesity.

CDH13 is associated with working memory performance in attention deficit/hyperactivity disorder

Different analytic strategies, including linkage, association and meta-analysis support a role of CDH13 in the susceptibility to attention deficit/hyperactivity disorder (ADHD). CDH13 codes for cadherin 13 (or H-cadherin), which is a member of a family of calcium-dependent cell-cell adhesion proteins and a regulator of neural cell growth. We tested the association between CDH13 on three executive functioning tasks that are promising endophenotypes of ADHD. An adjusted linear regression analysis was performed in 190 ADHD-affected Dutch probands of the IMAGE project. Three executive functions were examined: inhibition, verbal and visuo-spatial working memory (WM). We tested 2632 single nucleotide polymorphisms (SNPs) within CDH13 and 20 kb up- and downstream of the gene (capturing regulatory sequences). To adjust for multiple testing within the gene, we applied stringent permutation steps. Intronic SNP rs11150556 is associated with performance on the Verbal WM task. No other SNP showed gene-wide significance with any of the analyzed traits, but a 72-kb SNP block located 446 kb upstream of SNP rs111500556 showed suggestive evidence for association (P-value range 1.20E-03 to 1.73E-04) with performance in the same Verbal WM task. This study is the first to examine CDH13 and neurocognitive functioning. The mechanisms underlying the associations between CDH13 and the clinical phenotype of ADHD and verbal WM are still unknown. As such, our study may be viewed as exploratory, with the results presented providing interesting hypotheses for further testing.

The adolescent outcome of children with attention deficit hyperactivity disorder treated with methylphenidate or methylphenidate combined with multimodal behaviour therapy: results of a naturalistic follow-up study

OBJECTIVE

Children with attention deficit hyperactivity disorder (ADHD) who participated in a randomized clinical trial, which compared a brief intensive multimodal behaviour therapy combined with optimally titrated methylphenidate to optimally titrated methylphenidate alone (n = 45), were re-assessed at adolescence in a naturalistic follow-up 4.5 to 7.5 years after treatment. Also a matched normal control group was recruited (n = 23).

METHODS

Assessments at follow-up included diagnostic status, ADHD symptoms, oppositional and conduct behaviour, substance abuse symptoms and parenting stress.

RESULTS

Of the 24 adolescents participating in the follow-up study, 50% still met diagnostic criteria for ADHD. There were no significant differences between adolescents at follow-up and those lost for follow-up. At follow-up, adolescents in the combined treatment condition used significantly less medication than children in the methylphenidate condition; there were no other significant differences between the treatment conditions. The adolescents showed a significant decline in hyperactivity/impulsivity, oppositional and conduct disorder symptoms from post-test to follow-up. Only inattention symptoms increased from post-test to follow-up but not to pre-test levels. The adolescents originally diagnosed with ADHD fared significantly worse than the matched controls on all outcomes, except on conduct disorder and substance abuse symptoms.

CONCLUSIONS

Our study shows in adolescents, diagnosed with ADHD in childhood, age-dependent decline of ADHD symptoms, although they still fared significantly worse than matched normal controls. Implications of results are restricted by small samples size, and the results may be subject to chance findings and need replication before firm conclusions can be drawn.

Support for an independent familial segregation of executive and intelligence endophenotypes in ADHD families

BACKGROUND

Impairments in executive functioning (EF) and intelligence quotient (IQ) are frequently observed in children with attention deficit hyperactivity disorder (ADHD). The aim of this paper was twofold: first, to examine whether both domains are viable endophenotypic candidates for ADHD and second to investigate whether deficits in both domains tend to co-segregate within families.

METHOD

A large family-based design was used, including 238 ADHD families (545 children) and 147 control families (271 children). Inhibition, visuospatial and verbal working memory, and performance and verbal IQ were analysed.

RESULTS

Children with ADHD, and their affected and non-affected siblings were all impaired on the EF measures and verbal IQ (though unimpaired on performance IQ) and all measures correlated between siblings. Correlations and sibling cross-correlations were not significant between EF and IQ, though they were significant between the measures of one domain. Group differences on EF were not explained by group differences on IQ and vice versa. The discrepancy score between EF and IQ correlated between siblings, indicating that siblings resembled each other in their EF-IQ discrepancy instead of having generalized impairments across both domains. Siblings of probands who had an EF but not IQ impairment, showed a comparable disproportionate lower EF score in relation to IQ score. The opposite pattern was not significant.

CONCLUSIONS

The results supported the viability of EF and IQ as endophenotypic candidates for ADHD. Most findings support an independent familial segregation of both domains. Within EF, similar familial factors influenced inhibition and working memory. Within IQ, similar familial factors influenced verbal and performance IQ.

Treatment of attention deficit hyperactivity disorder in children. Predictors of treatment outcome

OBJECTIVE

The present study investigated the predictive power of anxiety, IQ, severity of ADHD and parental depression on the outcome of treatment in children with ADHD.

METHOD

Fifty children with ADHD (ages 8-12) were randomized to a 10-week treatment of methylphenidate or to a treatment of methylphenidate combined with multimodal behavior therapy. Prior to treatment predictors were assessed. Outcome was assessed separately for parents and teachers on a composite measure of inattentive, hyperactive, oppositional- and conduct disorder symptoms.

RESULTS

There was neither a significant difference between the two treatments at baseline nor did treatment condition predict outcome. Therefore the data were collapsed across the two treatments. A combination of anxiety and IQ predicted teacher-rated outcome, explaining 18% of the variance. Higher anxiety and higher IQ's indicated better treatment outcome. There were no significant predictors of the parent-rated outcome.

CONCLUSION

This study showed a small but significant predictive effect of IQ and anxiety on treatment outcome in children with ADHD.

CLINICAL IMPLICATIONS

This study supports the idea that for the treatment of ADHD children with comorbid anxiety and higher IQ respond better to the two most used treatments for ADHD.

The role of self-reported impulsivity and reward sensitivity versus neurocognitive measures of disinhibition and decision-making in the prediction of relapse in pathological gamblers

BACKGROUND

Disinhibition and decision-making skills play an important role in theories on the cause and outcome of addictive behaviors such as substance use disorders and pathological gambling. In recent studies, both disinhibition and disadvantageous decision-making strategies, as measured by neurocognitive tests, have been found to influence the course of substance use disorders. Research on factors affecting relapse in pathological gambling is scarce.

METHOD

This study investigated the effect of both self-reported impulsivity and reward sensitivity, and neurocognitively assessed disinhibition and decision-making under conflicting contingencies, on relapse in a group of 46 pathological gamblers.

RESULTS

Logistic regression analysis indicated that longer duration of the disorder and neurocognitive indicators of disinhibition (Stop Signal Reaction Time) and decision-making (Card Playing Task) were significant predictors of relapse (explaining 53% of the variance in relapse), whereas self-reported impulsivity and reward sensitivity did not significantly predict relapse. Overall classification accuracy was 76%, with a positive classification accuracy of 76% and a negative classification accuracy of 75%.

CONCLUSIONS

Duration of the disorder and neurocognitive measures of disinhibition and decision-making are powerful predictors of relapse in pathological gambling. The results suggest that endophenotypical neurocognitive characteristics are more promising in the prediction of relapse in pathological gambling than phenotypical personality characteristics. Neurocognitive predictors may be useful to guide treatment planning of follow-up contacts and booster sessions.

Efficacy of methylphenidate, psychosocial treatments and their combination in school-aged children with ADHD: a meta-analysis

INTRODUCTION

This meta-analysis compares effect-sizes of methylphenidate and psychosocial treatments and their combination on ADHD, concurrent oppositional, conduct symptoms, social behaviors and academic functioning.

METHOD

Several databases (PubMed, PsycInfo, ISI Web of Science) were searched for articles published between 1985 and September 2006. Inclusion criteria were: a diagnosis of ADHD; age from 6-12 years; a randomized controlled treatment design; efficacy established with parent and teacher rating scales; psychosocial treatments used were described as behavioral or cognitive-behavioral; the methylphenidate treatment was short-acting; and finally, treatment was conducted in a clinical setting.

RESULTS

ADHD outcomes showed large mean weighted effect-sizes for both methylphenidate and combined treatments, psychosocial treatments had a moderate mean weighted effect-size; a similar pattern emerged for oppositional and conducted behavior symptoms. Social behavior outcomes showed comparable moderate mean weighted effect-sizes for all treatments, while on academic functioning, all treatments had low mean weighted effect-sizes. There was no correlation between duration of psychosocial treatment and effect-size.

CONCLUSIONS

Both methylphenidate and psychosocial treatments are effective in reducing ADHD symptoms. However, psychosocial treatment yields smaller effects than both other treatment conditions. Psychosocial treatment has no additional value to methylphenidate for the reduction of ADHD and teacher rated ODD symptoms. However, for social behavior and parent rated ODD the three treatments were equally effective. For improvement of academic functioning no treatment was effective.

The association between parenting stress, depressed mood and informant agreement in ADHD and ODD

OBJECTIVE

In Attention Deficit Hyperactivity Disorder (ADHD) agreement between parents and teachers is often low. Parental depressed mood and parenting stress are considered to decrease informant agreement. This study examined informant agreement in children with ADHD and the association between parental depressed mood, parenting stress and agreement in the ratings of ADHD, ODD and CD symptoms.

METHOD

65 parents completed questionnaires on ADHD behavior of their child, parenting stress and depressed mood, teachers reported on ADHD behavior.

RESULTS

Low agreement was found for hyperactive and moderate agreement for inattentive, ODD and CD symptoms. Stepwise regression analyses showed that parenting stress, and not parental depressed mood accounted for 12% of the variance in inattention symptoms disagreement, 14% of the variance in hyperactive symptoms disagreement and 9% in oppositional behavior disagreement. No significant predictors were found for CD disagreement. The found effect was independent of stimulant medication use.

CONCLUSION

Parenting stress, but not parental depressed mood, was associated with the disagreement between parents and teachers on both ADHD and ODD symptoms. These results emphasize the importance of considering parenting stress in diagnosing ADHD and comorbid ODD.

A psychometric evaluation of the social skills rating system in children with attention deficit hyperactivity disorder

The social skills rating system (SSRS) was developed to assess social skills of children, as observed by multiple raters (teacher, parent, child). Studies of the SSRS have been conducted with handicapped, mentally retarded and learning disabled children. No studies have reported the psychometric properties of the SSRS in a clinical ADHD sample. This is important, because deficient social functioning is associated with ADHD. The present study assesses the psychometric properties of the teacher, parent and child versions of the SSRS in children with ADHD (n = 123), and normal controls (n = 239). Also, the social skills of children with ADHD, as rated on the SSRS were examined. Results support the factor structure and internal consistency of the original SSRS-teacher version. Moreover, support was found for 3 out of 4 scales of the SSRS-parent version. The factor structure of the SSRS-child version could not be replicated. An explanatory factor analysis on the SSRS-child version yielded two factors. Evidence was found for discriminative ability of the SSRS between normal controls and children with ADHD. Finally, informant agreement between raters was found to be poor.

Response inhibition in children with DSM-IV subtypes of AD/HD and related disruptive disorders: the role of reward

The current study had four aims: (a) to replicate previous findings of slow response inhibition in Attention Deficit/Hyperactivity Disorder (AD/HD), (b) to explore whether poor response inhibition in children with AD/HD is a core problem or rather a result of an underlying problem related to reward, (c) to investigate the specificity of poor response inhibition and the role of reward in relation to AD/HD, and (d) to study whether findings would be different for three subtypes of AD/HD. In order to address these issues, a stop paradigm was administered under a reward condition and under a nonreward condition to an AD/HD group (n=24), an Oppositional Defiant Disorder (ODD)/Conduct Disorder (CD) group (n=21), a comorbid AD/HD+ODD/CD group (n=27), and a normal control (NC) group (n=41). Firstly, contrary to prediction, none of the Disruptive Behavior Disorder (DBD) groups differed from the NC group with respect to the speed of the inhibition process. Secondly, it was shown that children with AD/HD and children with comorbid AD/HD+ODD/CD, but not children with ODD/CD alone, slowed down more dramatically in the reward condition than normal controls. This finding was interpreted as a strategy to increase the chance of being rewarded in children with AD/HD and children with comorbid AD/HD+ODD/CD, but not in children with pure ODD/CD. Finally, analysis of AD/HD subtypes did not change the main findings of this study.

Response execution and inhibition in children with AD/HD and other disruptive disorders: the role of behavioural activation

This study was aimed at (a) replicating findings of slow and variable response execution and slow response inhibition in Attention Deficit/Hyperactivity Disorder (AD/HD). (b) investigating whether these deficits are specifically related to AD/HD or may also be observed in Oppositional Defiant Disorder (ODD), and children comorbid for AD/HD+ODD, and (c) examining the role of activation level in task performance of children with AD/HD. To meet these aims, the stop paradigm was administered at three levels of activation, using a slow, medium, and fast presentation rate of stimuli, to 4 groups of children: 24 AD/HD children, 21 children with ODD, 27 children with comorbid AD/HD + ODD, and 41 normal controls. As hypothesized, children with AD/HD exhibited a slow response execution process with considerable variability in the speed of responding compared to normal controls. Slow response execution was also observed in the comorbid AD/HD+ODD group but not in the pure ODD group. Larger variability in the speed of responding was common to all disruptive groups compared with controls. In contrast to our hypothesis, no group differences emerged for inhibitory functioning. Finally, the slow event rate condition caused a further deterioration in the speed of the response execution process in both the AD/HD group and ODD group.

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.

Response inhibition and measures of psychopathology: a dimensional analysis

On the basis of Quay's (1988a, 1988b, 1993, 1997) model in which the Behavioral Inhibition System (BIS) and the Behavioral Activation System (BAS) are linked to various forms of child psychopathology, predictions were made regarding the relation between inhibitory control and two dimensions of psychopathology: externalizing and internalizing behavior. Inhibitory control was measured using two versions of Logan and Cowan's stop signal paradigm (1984; Logan, Cowan, & Davis, 1984; Osman, Kornblum, & Meyer, 1986, 1990). The primary outcome measure for the stop tasks was stop signal reaction time (SSRT) which measures the latency of the inhibition process. A positive relationship was predicted for externalizing behavior, whereas a negative relationship was predicted for internalizing behavior. A total of 42 non-clinical elementary school children, in the age range of 6 to 12 years, participated in the study. Externalizing behavior was positively related to response inhibition. Symptoms of ADHD seem to be better at predicting inhibitory functioning than symptoms of aggressive behavior disorders. Some support was found for a negative relation between internalizing behavior and inhibitory control. These findings support Quay's model and the discriminant validity of inhibitory control with regard to externalizing and internalizing behavior.

Attention deficit/hyperactivity disorder children with a 7-repeat allele of the dopamine receptor D4 gene have extreme behavior but normal performance on critical neuropsychological tests of attention

An association of the dopamine receptor D4 (DRD4) gene located on chromosome 11p15.5 and attention deficit/hyperactivity disorder (ADHD) has been demonstrated and replicated by multiple investigators. A specific allele [the 7-repeat of a 48-bp variable number of tandem repeats (VNTR) in exon 3] has been proposed as an etiological factor in attentional deficits manifested in some children diagnosed with this disorder. In the current study, we evaluated ADHD subgroups defined by the presence or absence of the 7-repeat allele of the DRD4 gene, using neuropsychological tests with reaction time measures designed to probe attentional networks with neuroanatomical foci in D4-rich brain regions. Despite the same severity of symptoms on parent and teacher ratings for the ADHD subgroups, the average reaction times of the 7-present subgroup showed normal speed and variability of response whereas the average reaction times of the 7-absent subgroup showed the expected abnormalities (slow and variable responses). This was opposite the primary prediction of the study. The 7-present subgroup seemed to be free of some of the neuropsychological abnormalities thought to characterize ADHD.

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.

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 hyperactive's 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 subject's 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.

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.

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 hyperactiviiy 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 Quay's 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.

Psychological mechanisms in hypochondriasis: attention-induced physical symptoms without sensory stimulation

Attention and expectancy have, in previous research, been demonstrated to influence symptom reporting and these findings can be relevant for understanding hypochondriasis. Earlier attention/expectancy effects on symptom reporting were studied when subjects were physically stimulated by the experimenter. If attention or expectancy produced symptom reporting, which plays a role in hypochondriasis, one expects that attention/expectancy will also produce symptoms in the absence of any deliberate physical stimulation. Eighty healthy volunteers were allocated to one of four groups: attention, expectancy, attention plus expectancy or a control condition. Compared to the control condition there was much higher symptom reporting in the 3 experimental groups. The experimental groups did not differ. It is argued that the effects of expectancy are obtained via increased attention. The relevance of the findings for understanding hypochondriasis is discussed.