Psychological heterogeneity in AD/HD--a dual pathway model of behaviour and cognition

Network-level assessment of reward-related activation in patients with ADHD and healthy individuals

INTRODUCTION

Reward processing is a key aspect of cognitive control processes, putatively instantiated by mesolimbic and mesocortical brain circuits. Deficient signaling within these circuits has been associated with psychopathology. We applied a network discovery approach to assess specific functional networks associated with reward processing in participants with attention-deficit/hyperactivity disorder (ADHD).

METHODS

To describe task-related processes in terms of integrated functional networks, we applied independent component analysis (ICA) to task response maps of 60 healthy participants who performed a monetary incentive delay (MID) task. The resulting components were interpreted on the basis of their similarity with group-level task responses as well as their similarity with brain networks derived from resting state fMRI analyses. ADHD-related effects on network characteristics including functional connectivity and communication between networks were examined in an independent sample comprising 150 participants with ADHD and 48 healthy controls.

RESULTS

We identified 23 components to be associated with 4 large-scale functional networks: the default-mode, visual, executive control, and salience networks. The salience network showed a specific association with reward processing as well as the highest degree of within-network integration. ADHD was associated with decreased functional connectivity between the salience and executive control networks as well as with peripheral brain regions.

CONCLUSIONS

Reward processing as measured with the MID task involves one reward-specific and three general functional networks. Participants with ADHD exhibited alterations in connectivity of both the salience and executive control networks and associated brain regions during task performance. Hum Brain Mapp 38:2359-2369, 2017. © 2017 Wiley Periodicals, Inc.

ADHS bei Erwachsenen

Zusammenfassung. Klassifizierungs- und Strukturierungsmöglichkeiten psychischer Störungen und Konstrukte sind in den letzten Jahren zu einem Schwerpunkt empirischer Forschung geworden. Im Mittelpunkt steht dabei die Debatte um die bisherige kategoriale versus einer neuen dimensionalen Sichtweise. ADHS gehört zu den Störungsbildern, für welche ein dimensionales Konzept plausibel erscheint. Empirische Belege hierfür liefern verschiedene taxonomische Studien an Kindern und Jugendlichen mit ADHS. Für Erwachsene gibt es bisher nur wenig empirische Untersuchungen zu dem Thema. Daher ist die vorliegende Studie eine erste Auseinandersetzung mit der Beschaffenheit von ADHS bei Erwachsenen, wobei den Befunden bei Kindern folgend von einer dimensionalen Struktur ausgegangen wird. Zwei Stichproben wurden zur Beantwortung der Fragestellung herangezogen: 605 Personen einer gesunden Normalstichprobe und 722 Personen aus einer klinischen Stichprobe, bestehend aus 336 Personen ohne ADHS-Diagnose und 386 Personen mit ADHS-Diagnose. Untersucht wurden alle Personen mittels der ADHS-Selbstbeurteilungsskala (ADHS-SB). Zur statistischen Überprüfung der Fragestellung wurden Diskriminanzanalysen und eine Faktorenanalyse durchgeführt, weiterhin wurden finite Mischverteilungsmodelle mit Hilfe des EM-Algorithmus gerechnet. Die Diskriminanzanalysen konnten zeigen, dass Grenzwerte nur bedingt dazu in der Lage sind, zwischen Personen mit und ohne ADHS zu diskriminieren. Die Faktorenanalyse ergab für alle Gruppen die gleiche Zwei-Faktoren-Lösung der ADHS, welche auch vom DSM-5 vorgeschlagen wird (Unaufmerksamkeit, Hyperaktivität/Impulsivität). Weiterhin wiesen die Mischmodelle der verschiedenen Gruppen keine Unterschiede auf, welche eine kategoriale Sichtweise rechtfertigen würden. Insgesamt ist eine dimensionale Struktur des Störungsbildes auch bei Erwachsenen als wahrscheinlich anzunehmen. Dies bedeutet, dass die Symptome der ADHS extreme Ausprägungen normaler psychischer Phänomene darstellen und es keine klaren Grenzen zwischen Personen mit und ohne einer adulten ADHS gibt. Trotz möglicher dimensionaler Struktur handelt es sich bei der ADHS um eine psychische Störung. Das Abklären funktioneller Beeinträchtigungen könnte vermehrt helfen, Behandlungswürdigkeit festzustellen.

Logical fallacies in animal model research

Background

Animal models of human behavioural deficits involve conducting experiments on animals with the hope of gaining new knowledge that can be applied to humans. This paper aims to address risks, biases, and fallacies associated with drawing conclusions when conducting experiments on animals, with focus on animal models of mental illness.

Conclusions

Researchers using animal models are susceptible to a fallacy known as false analogy, where inferences based on assumptions of similarities between animals and humans can potentially lead to an incorrect conclusion. There is also a risk of false positive results when evaluating the validity of a putative animal model, particularly if the experiment is not conducted double-blind. It is further argued that animal model experiments are reconstructions of human experiments, and not replications per se, because the animals cannot follow instructions. This leads to an experimental setup that is altered to accommodate the animals, and typically involves a smaller sample size than a human experiment. Researchers on animal models of human behaviour should increase focus on mechanistic validity in order to ensure that the underlying causal mechanisms driving the behaviour are the same, as relying on face validity makes the model susceptible to logical fallacies and a higher risk of Type 1 errors. We discuss measures to reduce bias and risk of making logical fallacies in animal research, and provide a guideline that researchers can follow to increase the rigour of their experiments.

Children with ADHD symptoms show decreased activity in ventral striatum during the anticipation of reward, irrespective of ADHD diagnosis

BACKGROUND

Changes in reward processing are thought to be involved in the etiology of attention-deficit/hyperactivity disorder (ADHD), as well as other developmental disorders. In addition, different forms of therapy for ADHD rely on reinforcement principles. As such, improved understanding of reward processing in ADHD could eventually lead to more effective treatment options. However, differences in reward processing may not be specific to ADHD, but may be a trans-diagnostic feature of disorders that involve ADHD-like symptoms.

METHODS

In this event-related fMRI study, we used a child-friendly version of the monetary incentive delay task to assess performance and brain activity during reward anticipation. Also, we collected questionnaire data to assess reward sensitivity in daily life. For final analyses, data were available for 27 typically developing children, 24 children with ADHD, and 25 children with an autism spectrum disorder (ASD) and ADHD symptoms.

RESULTS

We found decreased activity in ventral striatum during anticipation of reward in children with ADHD symptoms, both for children with ADHD as their primary diagnosis and in children with autism spectrum disorder and ADHD symptoms. We found that higher parent-rated sensitivity to reward was associated with greater anticipatory activity in ventral striatum for children with ADHD symptoms. In contrast, there was no relationship between the degree of ADHD symptoms and activity in ventral striatum.

CONCLUSIONS

We provide evidence of biological and behavioral differences in reward sensitivity in children with ADHD symptoms, regardless of their primary diagnosis. Ultimately, a dimensional brain-behavior model of reward sensitivity in children with symptoms of ADHD may be useful to refine treatment options dependent on reward processing.

NIRS-based neurofeedback training in a virtual reality classroom for children with attention-deficit/hyperactivity disorder: study protocol for a randomized controlled trial

Background

Children with attention-deficit/hyperactivity disorder (ADHD) suffer from attention deficits, motor hyperactivity, and impulsive behaviour. These impairments are experienced at home, at school, and with friends. Functional imaging studies show that ADHD behaviour and impairments in executive functions (EFs) are mirrored by aberrant neurophysiological functioning. Moreover, several studies show that ADHD behaviour, impairments in EFs, and a lack of self-control contribute to poor school performance. Non-pharmacological interventions such as neurofeedback training (NFT), for instance, aim at improving neurophysiological and neuropsychological functioning as well as behaviour. Consequently, NFT is expected to improve school performance, EFs, and self-control in children with ADHD. Generalization of acquired self-regulation skills from laboratory to real life is crucial for a transfer to everyday situations and is hypothesized to be facilitated via training using virtual reality (VR) environments. Consequently, experiencing NFT in VR is expected to yield greater effects than training in two dimensions (2D).

Methods/design

Ninety children with a clinical diagnosis of ADHD will be included in the study. Participants may be medicated or unmedicated. After random assignation to one of three conditions, all participants receive 15 training sessions of either near-infrared spectroscopy (NIRS)-based NFT in VR, NIRS-based NFT in 2D, or electromyogram-based biofeedback training in VR. ADHD symptoms, self-control, EF, health-related quality of life, school performance, and motor activity measured via parent, teacher, and child reports or objectively will be assessed before and after the intervention and at a 6 months follow-up. Furthermore, we are interested in parents’ expectations about the training’s effects.

Discussion

This is, to our knowledge, the first study investigating the efficacy of NFT for children with ADHD in a VR compared to a 2D environment. Furthermore, this study will contribute to the discussion about the efficacy and specific and unspecific effects of NFTs in children with ADHD. In addition to commonly assessed variables such as ADHD symptoms, NIRS and behavioural data obtained in EF measures, health-related quality of life, and parents’ expectations about the intervention’s effects, this study will investigate the effects on self-control, school performance, and motor activity.

Trial registration

ClinicalTrials.gov, NCT02572180. Registered on 19 November 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1769-3) contains supplementary material, which is available to authorized users.

Generating Attention, Inhibition, and Memory: A Pilot Randomized Trial for Preschoolers With Executive Functioning Deficits

This goal of this study was to assess the initial feasibility and efficacy of a play-based intervention targeting executive functions (EF) and parent-child relationships in preschoolers compared with an active control group. Preschoolers with EF deficits (M age = 3.7 ± 0.47, predominantly White boys) and their parents were randomized to intervention (n = 36) or active control (n = 32) conditions. Child performance on EF tasks, parent and masked teacher ratings of EF and behavior, and masked clinician ratings of severity were collected at baseline and at 3 and 6 months postbaseline. Partial eta-squared effect sizes at .02 or higher comparing performance across the two groups was considered evidence of meaningful, albeit small, intervention effects. Intervention effects were observed for parent ratings of inattention, hyperactivity/impulsivity, and number/severity of problems experienced in various home situations, teacher ratings of severity of problems in various school situations, parent and teacher ratings of overall impairment, and clinician ratings of impairment. Intervention effects for functional improvements were maintained at the 6-month follow-up. No effect of the intervention was observed on the objective EF measures, although parent ratings of emotional control were improved for children in the intervention group. An intervention utilizing play-based activities targeting EF, when administered in a structured way by parents, is a promising approach for improving behavior in preschoolers with self-regulation deficits. More work is needed to investigate potential impact on EF and to disentangle mechanisms of action. It may be that the intervention's focus on the structure and quality of parent-child interactions is a mediator of outcomes, rather than improved EFs.

Time-on-task effects in children with and without ADHD: depletion of executive resources or depletion of motivation?

Children with attention-deficit/hyperactivity disorder (ADHD) are characterized by deficits in their executive functioning and motivation. In addition, these children are characterized by a decline in performance as time-on-task increases (i.e., time-on-task effects). However, it is unknown whether these time-on-task effects should be attributed to deficits in executive functioning or to deficits in motivation. Some studies in typically developing (TD) adults indicated that time-on-task effects should be interpreted as depletion of executive resources, but other studies suggested that they represent depletion of motivation. We, therefore, investigated, in children with and without ADHD, whether there were time-on-task effects on executive functions, such as inhibition and (in)attention, and whether these were best explained by depletion of executive resources or depletion of motivation. The stop-signal task (SST), which generates both indices of inhibition (stop-signal reaction time) and attention (reaction time variability and errors), was administered in 96 children (42 ADHD, 54 TD controls; aged 9-13). To differentiate between depletion of resources and depletion of motivation, the SST was administered twice. Half of the participants was reinforced during second task performance, potentially counteracting depletion of motivation. Multilevel analyses indicated that children with ADHD were more affected by time-on-task than controls on two measures of inattention, but not on inhibition. In the ADHD group, reinforcement only improved performance on one index of attention (i.e., reaction time variability). The current findings suggest that time-on-task effects in children with ADHD occur specifically in the attentional domain, and seem to originate in both depletion of executive resources and depletion of motivation. Clinical implications for diagnostics, psycho-education, and intervention are discussed.

Neuropsychological Functioning in Adults With ADHD and Adults With Other Psychiatric Disorders

OBJECTIVE

The aim was to investigate how well neuropsychological measures can discriminate between adults with ADHD and those with other psychiatric disorders.

METHOD

Adults with ADHD and a clinical control group ( n = 110) were included. Neuropsychological functioning was investigated using measures of inhibition, working memory, set shifting, planning, fluency, reaction-time variability, and delay aversion.

RESULTS

Adults with ADHD performed more poorly compared with clinical controls with regard to all constructs. The effects of verbal memory, inhibition, set shifting, fluency, and delay aversion remained significant when controlling for IQ. However, when controlling for basic cognitive functions, only the effects of inhibition, fluency, and delay aversion were significant. Sensitivity ranged between 64% and 75%, and specificity between 66% and 81%.

CONCLUSION

Neuropsychological tests have a relatively poor ability to discriminate between adults with ADHD and clinical controls, but they may be used to identify individuals at particularly high risk for poor daily functioning.

What to expect and when to expect it: an fMRI study of expectancy in children with ADHD symptoms

Changes in cognitive control and timing have both been implicated in ADHD. Both are involved in building and monitoring expectations about the environment, and altering behavior if those expectations are violated. In ADHD, problems with expectations about future events have high face validity, as this would be associated with behavior that is inappropriate only given a certain context, similar to symptoms of the disorder. In this fMRI study, we used a timing manipulated go/nogo task to assess brain activity related to expectations about what (cognitive control) and when (timing) events would occur. We hypothesized that problems in building expectations about the environment are a more general, trans-diagnostic characteristic of children with hyperactive, impulsive and inattentive symptoms. To address this, we included children with ASD and symptoms of ADHD, in addition to children with ADHD and typically developing children. We found between-group differences in brain activity related to expectations about when (timing), but not what events will occur (cognitive control). Specifically, we found timing-related hypo-activity that was in part unique to children with a primary diagnosis of ADHD (left pallidum) and in part shared by children with similar levels of ADHD symptoms and a primary diagnosis of ASD (left subthalamic nucleus). Moreover, we found poorer task performance related to timing, but only in children with ASD and symptoms of ADHD. Ultimately, such neurobiological changes in children with ADHD symptoms may relate to a failure to build or monitor expectations and thereby hinder the efficiency of their interaction with the environment.

Investigating the Impact of Cognitive Load and Motivation on Response Control in Relation to Delay Discounting in Children with ADHD

Attention-deficit/hyperactivity disorder (ADHD) is characterized by deficits in impulse control across a range of behaviors, from simple actions to those involving complex decision-making (e.g., preference for smaller-sooner versus larger later rewards). This study investigated whether changes in motor response control with increased cognitive load and motivational contingencies are associated with decision-making in the form of delay discounting among 8-12 year old children with and without ADHD. Children with ADHD (n = 26; 8 girls) and typically developing controls (n = 40; 11 girls) completed a standard go/no-go (GNG) task, a GNG task with motivational contingencies, a GNG task with increased cognitive load, and two measures of delay discounting: a real-time task in which the delays and immediately consumable rewards are experienced in real-time, and a classic task involving choices about money at longer delays. Children with ADHD, particularly girls, exhibited greater delay discounting than controls during the real-time discounting task, whereas diagnostic groups did not significantly differ on the classic discounting task. The effect of cognitive load on response control was uniquely associated with greater discounting on the real-time task for children with ADHD, but not for control children. The effect of motivational contingencies on response control was not significantly associated with delay discounting for either diagnostic group. The findings from this study help to inform our understanding of the factors that influence deficient self-control in ADHD, suggesting that impairments in cognitive control may contribute to greater delay discounting in ADHD.

Neuropsicologia do Transtorno de Déficit de Atenção/Hiperatividade: Modelos Neuropsicológicos e Resultados de Estudos Empíricos

Resumo Diferentes modelos teóricos foram propostos para explicar os déficits neuropsicológicos e seu impacto no comportamento de indivíduos com Transtorno de Déficit de Atenção/Hiperatividade (TDAH). Os objetivos deste artigo serão apresentar os principais modelos neuropsicológicos do TDAH e possibilitar uma atualização acerca dos principais achados relacionados ao funcionamento neuropsicológico de pacientes com esse diagnóstico. Revisões e meta-análises sobre funcionamento executivo, aversão à resposta tardia, processamento temporal e variações intraindividuais no tempo de reação são apresentadas. O perfil neuropsicológico de pacientes com TDAH é heterogêneo e testes neuropsicológicos não são suficientemente sensíveis e específicos para realização do diagnóstico, embora sejam muito importantes na identificação do perfil cognitivo para estabelecimento de um plano de tratamento mais abrangente e adequado às necessidades especificas de cada paciente.

Cognitive Load Differentially Impacts Response Control in Girls and Boys with ADHD

Children with attention-deficit hyperactivity disorder (ADHD) consistently show impaired response control, including deficits in response inhibition and increased intrasubject variability (ISV) compared to typically-developing (TD) children. However, significantly less research has examined factors that may influence response control in individuals with ADHD, such as task or participant characteristics. The current study extends the literature by examining the impact of increasing cognitive demands on response control in a large sample of 81children with ADHD (40 girls) and 100 TD children (47 girls), ages 8-12 years. Participants completed a simple Go/No-Go (GNG) task with minimal cognitive demands, and a complex GNG task with increased cognitive load. Results showed that increasing cognitive load differentially impacted response control (commission error rate and tau, an ex-Gaussian measure of ISV) for girls, but not boys, with ADHD compared to same-sex TD children. Specifically, a sexually dimorphic pattern emerged such that boys with ADHD demonstrated higher commission error rate and tau on both the simple and complex GNG tasks as compared to TD boys, whereas girls with ADHD did not differ from TD girls on the simple GNG task, but showed higher commission error rate and tau on the complex GNG task. These findings suggest that task complexity influences response control in children with ADHD in a sexually dimorphic manner. The findings have substantive implications for the pathophysiology of ADHD in boys versus girls with ADHD.

Modeling Individual Differences in the Go/No-go Task with a Diffusion Model

The go/no-go task is one in which there are two choices, but the subject responds only to one of them, waiting out a time-out for the other choice. The task has a long history in psychology and modern applications in the clinical/neuropsychological domain. In this article we fit a diffusion model to both experimental and simulated data. The model is the same as the two-choice model and assumes that there are two decision boundaries and termination at one of them produces a response and at the other, the subject waits out the trial. In prior modeling, both two-choice and go/no-go data were fit simultaneously and only group data were fit. Here the model is fit to just go/no-go data for individual subjects. This allows analyses of individual differences which is important for clinical applications. First, we fit the standard two-choice model to two-choice data and fit the go/no-go model to RTs from one of the choices and accuracy from the two-choice data. Parameter values were similar between the models and had high correlations. The go/no-go model was also fit to data from a go/no-go version of the task with the same subjects as the two-choice task. A simulation study with ranges of parameter values that are obtained in practice showed similar parameter recovery between the two-choice and go/no-go models. Results show that a diffusion model with an implicit (no response) boundary can be fit to data with almost the same accuracy as fitting the two-choice model to two-choice data.

Behavioral sensitivity to changing reinforcement contingencies in attention-deficit hyperactivity disorder

BACKGROUND

Altered sensitivity to positive reinforcement has been hypothesized to contribute to the symptoms of attention-deficit hyperactivity disorder (ADHD). In this study, we evaluated the ability of children with and without ADHD to adapt their behavior to changing reinforcer availability.

METHOD

Of one hundred sixty-seven children, 97 diagnosed with ADHD completed a signal-detection task in which correct discriminations between two stimuli were associated with different frequencies of reinforcement. The response alternative associated with the higher rate of reinforcement switched twice during the task without warning. For a subset of participants, this was followed by trials for which no reinforcement was delivered, irrespective of performance.

RESULTS

Children in both groups developed an initial bias toward the more frequently reinforced response alternative. When the response alternative associated with the higher rate of reinforcement switched, the children's response allocation (bias) followed suit, but this effect was significantly smaller for children with ADHD. When reinforcement was discontinued, only children in the control group modified their response pattern.

CONCLUSIONS

Children with ADHD adjust their behavioral responses to changing reinforcer availability less than typically developing children, when reinforcement is intermittent and the association between an action and its consequences is uncertain. This may explain the difficulty children with ADHD have adapting their behavior to new situations, with different reinforcement contingencies, in daily life.

Applicability of the Stop-Signal Task for Preschoolers With ADHD

Inhibitory deficits of children with attention deficit/hyperactivity disorder (ADHD) are well documented. However, the specific inhibition ability (stopping an ongoing response) of preschoolers with ADHD is little reported. This study adopted the tracking stop-signal task to examine preschoolers with ADHD. Twenty-eight children with ADHD (M = 6.1 year, SD = 0.6) were compared to 31 comparison children (M = 6.0 year, SD = 0.6) on a measure of inhibitory control. The results showed that preschool children with ADHD performed worse than their control groups on the stop-signal task, using the omission error index, implying an attention deficit. However, preschool children with ADHD did not exhibit significantly slower stop-signal reaction times relative to the control group. The ability of controlled response inhibition of preschool children may not be mature.

Ventral striatal hyperconnectivity during rewarded interference control in adolescents with ADHD

OBJECTIVE

Attention-deficit/hyperactivity disorder (ADHD) is characterized by cognitive deficits (e.g., interference control) and altered reward processing. Cognitive control is influenced by incentive motivation and according to current theoretical models, ADHD is associated with abnormal interactions between incentive motivation and cognitive control. However, the neural mechanisms by which reward modulates cognitive control in individuals with ADHD are unknown.

METHOD

We used event-related functional resonance imaging (fMRI) to study neural responses during a rewarded Stroop color-word task in adolescents (14-17 years) with ADHD (n = 25; 19 boys) and healthy controls (n = 33; 22 boys).

RESULTS

Adolescents with ADHD showed increased reward signaling within the superior frontal gyrus and ventral striatum (VS) relative to controls. Importantly, functional connectivity analyses revealed a hyperconnectivity between VS and motor control regions in the ADHD group, as a function of reward-cognitive control integration. Connectivity was associated with performance improvement in controls but not in the ADHD group, suggesting inefficient connectivity.

CONCLUSION

Adolescents with ADHD show increased neural sensitivity to rewards and its interactions with interference control in VS and motor regions, respectively. The findings support theoretical models of altered reward-cognitive control integration in individuals with ADHD.

Emotional dysregulation in children with attention-deficit/hyperactivity disorder

Emotional dysregulation is increasingly recognized as a core feature of attention-deficit/hyperactivity disorder (ADHD). The purpose of the present systematic literature review was to identify published data related to the neuropsychology of emotional dysregulation in children with ADHD. The literature obtained is discussed in the contexts of deficits in emotional control, impairments in executive function, the emotional components of comorbidities, neurophysiological and autonomic correlates of emotional dysregulation, and the significance of multiple neuropsychological pathways of ADHD on emotional dysregulation. These various lines of evidence are used to create a patient-oriented conceptual model framework of the pathway from stimulus to inappropriate internalized (sadness, moodiness) or externalized (anger, aggressiveness) emotional responses. The article concludes by calling for continued research into the development of reliable and universally accepted measures of emotional dysregulation in order to provide children affected with ADHD, and their caregivers, some explanation for their emotional lability and, ultimately, to be used as tools to evaluate potential treatments.

Reward Contrast Effects on Impulsive Choice and Timing in Rats

Despite considerable interest in impulsive choice as a predictor of a variety of maladaptive behaviors, the mechanisms that drive choice behavior are still poorly understood. The present study sought to examine the influence of one understudied variable, reward magnitude contrast, on choice and timing behavior as changes in magnitude commonly occur within choice procedures. In addition, assessments of indirect effects on choice behavior through magnitude-timing interactions were assessed by measuring timing within the choice task. Rats were exposed to choice procedures composed of different pairs of magnitudes of rewards for either the smaller-sooner (SS) or larger-later (LL) option. In Phase 2, the magnitude of reward either increased or decreased by 1 pellet in different groups (LL increase = 1v1→1v2; SS decrease = 2v2 → 1v2; SS increase = 1v2 → 2v2), followed by a return to baseline in Phase 3. Choice behavior was affected by the initial magnitudes experienced in the task, demonstrating a strong anchor effect. The nature of the change in magnitude affected choice behavior as well. Timing behavior was also affected by the reward contrast manipulation albeit to a lesser degree and the timing and choice effects were correlated. The results suggest that models of choice behavior should incorporate reinforcement history, reward contrast elements, and magnitude-timing interactions, but that direct effects of reward contrast on choice should be given more weight than the indirect reward-timing interactions. A better understanding of the factors that contribute to choice behavior could supply key insights into this important individual differences variable.

Factorial Validity of the ADHD Adult Symptom Rating Scale in a French Community Sample: Results From the ChiP-ARD Study

OBJECTIVE

Recent publications reported that a bifactor model better represented the underlying structure of ADHD than classical models, at least in youth. The Adult ADHD Symptoms Rating Scale (ASRS) has been translated into many languages, but a single study compared its structure in adults across Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) and International Classification of Diseases (ICD-10) classifications.

METHOD

We investigated the factor structure, reliability, and measurement invariance of the ASRS among a community sample of 1,171 adults.

RESULTS

Results support a bifactor model, including one general ADHD factor and three specific Inattention, Hyperactivity, and Impulsivity factors corresponding to ICD-10, albeit the Impulsivity specific factor was weakly defined. Results also support the complete measurement invariance of this model across gender and age groups, and that men have higher scores than women on the ADHD G-factor but lower scores on all three S-factors.

CONCLUSION

Results suggest that a total ASRS-ADHD score is meaningful, reliable, and valid in adults. (J. of Att. Dis. 2016; 20(6) 530-541).

Aberrant local striatal functional connectivity in attention-deficit/hyperactivity disorder

BACKGROUND

Task-based and resting-state functional Magnetic Resonance Imaging (fMRI) studies report attention-deficit/hyperactivity disorder (ADHD)-related alterations in brain regions implicated in cortico-striatal networks. We assessed whether ADHD is associated with changes in the brain's global cortico-striatal functional architecture, or whether ADHD-related alterations are limited to local, intrastriatal functional connections.

METHODS

We included a cohort of adolescents with ADHD (N = 181) and healthy controls (N = 140) and assessed functional connectivity of nucleus accumbens, caudate nucleus, anterior putamen, and posterior putamen. To assess global cortico-striatal functional architecture we computed whole-brain functional connectivity by including all regions of interest in one multivariate analysis. We assessed local striatal functional connectivity using partial correlations between the time series of the striatal regions.

RESULTS

Diagnostic status did not influence global cortico-striatal functional architecture. However, compared to controls, participants with ADHD exhibited significantly increased local functional connectivity between anterior and posterior putamen (p = .0003; ADHD: z = .30, controls: z = .24). Results were not affected by medication use or comorbid oppositional defiant disorder and conduct disorder.

CONCLUSIONS

Our results do not support hypotheses that ADHD is associated with alterations in cortico-striatal networks, but suggest changes in local striatal functional connectivity. We interpret our findings as aberrant development of local functional connectivity of the putamen, potentially leading to decreased functional segregation between anterior and posterior putamen in ADHD.

Impulsivity is relevant for trauma exposure and PTSD symptoms in a non-clinical population

Impulsivity is a relevant construct for explaining both normal individual differences in personality and more extreme personality disorder, and is often investigated within clinical populations. This study aims to explore the college students' impulsivity patterns and to investigate the association across levels of impulsivity with trauma exposure and PTSD development in a non-clinical population. A one-phase census survey of seven college institutions assessed 2213 students in three metropolitan regions of Northeastern Brazil. All subjects anonymously completed a self-applied protocol consisting of: a socio-demographic questionnaire, Trauma History Questionnaire (THQ), PTSD Checklist (PCL-C), and Barratt Impulsiveness Scale (BIS-11). The median for frequency of trauma exposure was 4 events for people with low and normal impulsivity, and 6 for highly impulsive ones. Individuals with higher impulsivity presented earlier exposition than non-impulsive ones, and worst outcome: 12.4% with PTSD, against 8.4% and 2.3% (normal and low impulsivity). Of the three factors of impulsivity, the Attentional factor conferred the strongest association with PTSD development. Results suggest that impulsivity is also a relevant trait in a non-clinical population and is associated with trauma exposure and PTSD. Strategies to promote mental health in adolescents may be pertinent, especially with the aim of managing impulsivity.

Top-Down Dysregulation-From ADHD to Emotional Instability

Deficient cognitive top-down executive control has long been hypothesized to underlie inattention and impulsivity in attention-deficit/hyperactivity disorder (ADHD). However, top-down cognitive dysfunction explains a modest proportion of the ADHD phenotype whereas the salience of emotional dysregulation is being noted increasingly. Together, these two types of dysfunction have the potential to account for more of the phenotypic variance in patients diagnosed with ADHD. We develop this idea and suggest that top-down dysregulation constitutes a gradient extending from mostly non-emotional top-down control processes (i.e., “cool” executive functions) to mainly emotional regulatory processes (including “hot” executive functions). While ADHD has been classically linked primarily to the former, conditions involving emotional instability such as borderline and antisocial personality disorder are closer to the other. In this model, emotional subtypes of ADHD are located at intermediate levels of this gradient. Neuroanatomically, gradations in “cool” processing appear to be related to prefrontal dysfunction involving dorsolateral prefrontal cortex (dlPFC) and caudal anterior cingulate cortex (cACC), while “hot” processing entails orbitofrontal cortex and rostral anterior cingulate cortex (rACC). A similar distinction between systems related to non-emotional and emotional processing appears to hold for the basal ganglia (BG) and the neuromodulatory effects of the dopamine system. Overall we suggest that these two systems could be divided according to whether they process non-emotional information related to the exteroceptive environment (associated with “cool” regulatory circuits) or emotional information related to the interoceptive environment (associated with “hot” regulatory circuits). We propose that this framework can integrate ADHD, emotional traits in ADHD, borderline and antisocial personality disorder into a related cluster of mental conditions.

Teacher Ratings of the ADHD-RS IV in a Community Sample: Results From the ChiP-ARD Study

OBJECTIVE

Validated instruments to assess ADHD are still unavailable in many languages other than English for teachers, which constitutes a clear obstacle to screening, diagnosis, and treatment of ADHD in many European countries.

METHOD

Teachers rated 892 youths using the ADHD Rating Scale (ADHD-RS). We investigated the factor structure, reliability, and measurement invariance based on confirmatory factor analyses.

RESULTS

Results support a bifactor model, including one general ADHD factor and two specific Inattention and Hyperactivity-Impulsivity factors. But the latter is improperly defined calling into question the existence of a Predominantly Hyperactivity-Impulsivity subtype. The measurement invariance is fully supported across gender, age groups, and Gender × Age Groups.

CONCLUSION

Results support the multiple-pathways hypothesis and suggest that a total ADHD score is meaningful, reliable, and valid, as well as specific assessments of Inattention. Some youths--especially older ones--may present a profile of ADHD particularly marked by Inattention symptoms.

An integrated feature ranking and selection framework for ADHD characterization

Today, diagnosis of attention deficit hyperactivity disorder (ADHD) still primarily relies on a series of subjective evaluations that highly rely on a doctor’s experiences and intuitions from diagnostic interviews and observed behavior measures. An accurate and objective diagnosis of ADHD is still a challenge and leaves much to be desired. Many children and adults are inappropriately labeled with ADHD conditions, whereas many are left undiagnosed and untreated. Recent advances in neuroimaging studies have enabled us to search for both structural (e.g., cortical thickness, brain volume) and functional (functional connectivity) abnormalities that can potentially be used as new biomarkers of ADHD. However, structural and functional characteristics of neuroimaging data, especially magnetic resonance imaging (MRI), usually generate a large number of features. With a limited sample size, traditional machine learning techniques can be problematic to discover the true characteristic features of ADHD due to the significant issues of overfitting, computational burden, and interpretability of the model. There is an urgent need of efficient approaches to identify meaningful discriminative variables from a higher dimensional feature space when sample size is small compared with the number of features. To tackle this problem, this paper proposes a novel integrated feature ranking and selection framework that utilizes normalized brain cortical thickness features extracted from MRI data to discriminate ADHD subjects against healthy controls. The proposed framework combines information theoretic criteria and the least absolute shrinkage and selection operator (Lasso) method into a two-step feature selection process which is capable of selecting a sparse model while preserving the most informative features. The experimental results showed that the proposed framework generated the highest/comparable ADHD prediction accuracy compared with the state-of-the-art feature selection approaches with minimum number of features in the final model. The selected regions of interest in our model were consistent with recent brain–behavior studies of ADHD development, and thus confirmed the validity of the selected features by the proposed approach.

Neuropsychological heterogeneity in preschool ADHD: investigating the interplay between cognitive, affective and motivation-based forms of regulation

There is a trend toward diagnosing ADHD prior to school entry. Despite this, there is a lack of studies investigating ADHD in the preschool years, at least studies including a large range of different neuropsychological functions. Our knowledge of the independent effects of different neuropsychological functions in relation to preschool ADHD is therefore limited. In order to address this issue, the present study investigated cognitive, affective, and motivation-based regulation in relation to ADHD symptoms in 104 preschool children (age M = 67.33 months, SD = 10.10; 65 % boys). Results showed that these regulatory processes were all significantly related to ADHD symptoms and that most of these relations remained after controlling for comorbid conduct problems. Most previous preschool studies have only included cognitive regulation, and to some extent motivation-based regulation. By also including affective regulation, we were able to explain a larger proportion of the variance in ADHD symptoms. However, it should be noted that the amount of variance explained was still small in comparison with what has been found in previous studies of school-aged children. This finding could be taken as an indication that further studies examining the nature of preschool ADHD are needed, and that it may be necessary to look beyond the neuropsychological factors that have been linked to the disorder in older children and adults.

Neurocognitive and psychiatric dimensions of hot, but not cool, impulsivity predict HIV sexual risk behaviors among drug users in protracted abstinence

BACKGROUND

Impulsivity is an important risk factor for HIV risky drug and sexual behaviors. Research identifies hot (i.e. affectively-mediated, reward-based) and cool (motoric, attentional, independent of context) neurocognitive and psychiatric dimensions of impulsivity, though the impact of specific drugs of abuse on these varieties of impulsivity remains an open question.

OBJECTIVES

The present study examined the associations of neurocognitive and psychiatric varieties of hot and cool impulsivity with measures of lifetime and recent sexual risk behaviors among users of different classes of drugs.

METHODS

The study sample was comprised of drug users in protracted (> 1 year) abstinence: heroin mono-dependent (n = 61), amphetamine mono-dependent (n = 44), and polysubstance dependent (n = 73). Hot impulsivity was operationalized via neurocognitive tasks of reward-based decision-making and symptoms of psychopathy. Cool impulsivity was operationalized via neurocognitive tasks of response inhibition and symptoms of attention deficit/hyperactivity disorder (ADHD).

RESULTS

Hot impulsivity was associated with sexual risk behaviors among heroin and amphetamine users in protracted abstinence, whereas cool impulsivity was not associated with sexual risk behaviors among any drug-using group. Neurocognitive hot impulsivity was associated with recent (past 30-day) sexual risk behaviors, whereas psychopathy was associated with sexual risk behaviors during more remote time-periods (past 6 month and lifetime) and mediated the association between heroin dependence and past 6-month sexual risk behaviors.

CONCLUSION

Assessments and interventions aimed at reducing sexual risk behaviors among drug users should focus on hot neurocognitive and psychiatric dimensions of impulsivity, such as decision-making and psychopathy. Cool dimensions of impulsivity such as response inhibition and ADHD were not related to sexual risk behaviors among drug users in protracted abstinence.

Interactions between levels of attention ability and levels of bilingualism in children's executive functioning

Attention difficulty is associated with poor performance on executive functioning (EF) tasks, yet EF is enhanced in bilingual children. However, no research to date has investigated the possible interaction between bilingualism and attention ability in children to determine the consequences for EF when both are present. We assessed a sample of typically developing children who were 8 to 11 years old for their ability in attention control and level of bilingualism on the basis of questionnaires completed by parents and teachers. Children performed three tasks requiring aspects of EF: stop signal task (inhibition), flanker task (interference control), and frogs matrices task (spatial working memory). Results from hierarchical regressions confirmed that both attention ability and bilingualism contributed to performance on the EF tasks. Where interaction effects were significant, they showed that attention ability was a stronger predictor for an inhibition task, namely stop signal, and bilingualism a stronger predictor for an interference task, namely flanker. Furthermore, these results allow us to discuss the relation between EF and attention ability.

Animal-Assisted Interventions for Children with Attention Deficit/Hyperactivity Disorder: A Theoretical Review and Consideration of Future Research Directions

Attention Deficit Hyperactivity Disorder (ADHD) is one of the most prevalent neurodevelopmental disorders and is characterized by core symptoms of inattention, impulsivity, and hyperactivity. Given the limitations of the existing treatment strategies, it seems necessary to consider the further exploration of alternative treatment approaches. In this review, the application and complementary use of animal-assisted interventions to the treatment of ADHD were discussed. Several mechanisms including calming, socializing, motivating, and cognitive effects of animal-assisted interventions were explored. Since studies directly investigating these effects on ADHD are scarce, so each of them were examined in terms of how it could benefit the treatment of ADHD. These effects can have a positive effect on several core symptoms of ADHD.

Self-injury, aggression and destruction in children with severe intellectual disability: Incidence, persistence and novel, predictive behavioural risk markers

BACKGROUND

A risk informed, early intervention strategy for self-injurious, aggressive and destructive behaviours in children with severe intellectual disability is gaining support. The aims of this study were to establish the cumulative incidence and persistence of self-injury, aggression and destruction and the relationship between these behaviours and two potentially predictive behavioural risk markers (repetitive behaviour, and impulsivity and overactivity) in children at high risk.

METHODS

In a longitudinal design self-injury, aggression and destruction were assessed by teachers of 417 children with severe intellectual disability on two occasions separated by 15-18 months.

RESULTS

Aggression, destruction and self-injury were persistent (69%, 57% and 58% respectively). Repetitive and restricted behaviours and interests (RRBI) and overactivity/impulsivity (O/I) were significantly associated with aggression (O/I OR=1.291, p<.001), destruction (RRBI OR 1.201, p=.013; O/I OR 1.278, p<.001) and/or self-injury (RRBI, OR 1.25, p=.004; O/I OR=1.117, p<.001). The relative risk of the cumulative incidence of self-injury, aggression and destruction was significantly increased by repetitive and restricted behaviours and interests (self-injury 2.66, destruction 2.16) and/or overactivity/impulsivity (aggression 2.42, destruction 2.07).

CONCLUSIONS

The results provide evidence that repetitive and restricted behaviours and interests, and overactivity/impulsivity, are risk markers for the onset of self-injury, aggression and destruction within the already high risk group of children with severe intellectual disability.

Treatment Programs for Students With Attention Deficit Hyperactivity Disorder: A Meta-Analysis Study

Context:

The aim of this study was to determine the experimental evidence of treatment/intervention programs for deficits in social skills, attention, and behavioral disorder in children and adolescents with attention deficit hyperactivity disorder (ADHD).

Evidence Acquisition:

Meta-analysis procedures were employed to investigate whether children and adolescents with ADHD exhibit deficits in attention and social skills. A total of 17 empirical research studies published between 2000 and 2013 met our inclusion criteria. Attention and social skills measures were categorized according to both modality and type of processing required.

Results:

Children with ADHD exhibited deficits in multiple components of attention and social skills that were not related to language-learning disorders and weaknesses in general intellectual abilities. The overall percentage effect for attention and social skills in students with ADHD was calculated (effect size = 0. 79, confidence interval = 0.57 - 1.08). This meta-analysis study showed that treatment programs reduced attention deficit and social skills in ADHD children and adolescents.

Conclusions:

The evidence of attention and social skills deficits in children with ADHD supports recent studies in ADHD deficits. Further research is required to explain in detail the nature, severity, and specificity of the deficits in individuals with ADHD.

Cognitive heterogeneity in adult attention deficit/hyperactivity disorder: A systematic analysis of neuropsychological measurements

Attention Deficit/Hyperactivity Disorder (ADHD) in childhood is associated with impaired functioning in multiple cognitive domains: executive functioning (EF), reward and timing. Similar impairments have been described for adults with persistent ADHD, but an extensive investigation of neuropsychological functioning in a large sample of adult patients is currently lacking. We systematically examined neuropsychological performance on tasks measuring EF, delay discounting, time estimation and response variability using univariate ANCOVA's comparing patients with persistent ADHD (N=133, 42% male, mean age 36) and healthy adults (N=132, 40% male, mean age 36). In addition, we tested which combination of variables provided the highest accuracy in predicting ADHD diagnosis. We also estimated for each individual the severity of neuropsychological dysfunctioning. Lastly, we investigated potential effects of stimulant medication and a history of comorbid major depressive disorder (MDD) on performance. Compared to healthy adults, patients with ADHD showed impaired EF, were more impulsive, and more variable in responding. However, effect sizes were small to moderate (range: 0.05-0.70) and 11% of patients did not show neuropsychological dysfunctioning. The best fitting model predicting ADHD included measures from distinct cognitive domains (82.1% specificity, 64.9% sensitivity). Furthermore, patients receiving stimulant medication or with a history of MDD were not distinctively impaired. To conclude, while adults with ADHD as a group are impaired on several cognitive domains, the results confirm that adult ADHD is neuropsychologically heterogeneous. This provides a starting point to investigate individual differences in terms of impaired cognitive pathways.

Executive attention control and emotional responding in attention-deficit/hyperactivity disorder--A functional MRI study

Background

There are suggestions that patients with attention-deficit/hyperactivity disorder (ADHD) show impairment in executive attention control and emotion regulation. This study investigated emotion regulation as a function of the recruitment of executive attention in patients with ADHD.

Methods

Thirty-five healthy children/adolescents (mean age = 13.91) and twenty-six children/adolescents with ADHD (mean age = 14.53) participated in this fMRI study. They completed the affective Stroop paradigm viewing positive, neutral and negative images under varying cognitive loads. A 3-way ANOVA (diagnosis-by-condition-by-emotion) was conducted on the BOLD response data. Following this, 2 3-way ANOVAs (diagnosis-by-condition-by-emotion) were applied to context-dependent psychophysiological interaction (gPPI) analyses generated from a dorsomedial frontal cortex and an amygdala seed (identified from the BOLD response ANOVA main effects of condition and emotion respectively).

Results

A diagnosis-by-condition interaction within dorsomedial frontal cortex revealed reduced recruitment of dorsomedial frontal cortex as a function of increased task demands in the children/adolescents with ADHD relative to healthy children/adolescents. The level of reduction in recruitment of dorsomedial frontal cortex was significantly correlated with symptom severity (total and hyperactivity) measured by Conner's Parent Report Scale in the children/adolescents with ADHD. In addition, analysis of gPPI data from a dorsomedial frontal cortex seed revealed significant diagnosis-by-condition interactions within lateral frontal cortex; connectivity between dorsomedial frontal cortex and lateral frontal cortex was reduced in the patients with ADHD relative to comparison youth during congruent and incongruent task trials relative to view trials. There were no interactions of group, or main effect of group, within the amygdala in the BOLD response ANOVA (though children/adolescents with ADHD showed increased responses to positive images within temporal cortical regions during task trials; identified by the diagnosis-by-condition-by-emotion interaction). However, analysis of gPPI data from an amygdala seed revealed decreased connectivity between amygdala and lentiform nucleus in the presence of emotional stimuli in children/adolescents with ADHD (diagnosis-by-emotion interaction).

Conclusion

The current study demonstrated disrupted recruitment of regions implicated in executive function and impaired connectivity within those regions in children/adolescents with ADHD. There were also indications of heightened representation of emotional stimuli in patients with ADHD. However, as the findings were specific for positive stimuli, the suggestion of a general failure in emotion regulation in ADHD was not supported.

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ADHD showed decreased dorsomedial frontal cortex activity with increased cognitive demand.

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Decreased dorsomedial frontal cortex activity was correlated with symptom severity of ADHD.

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Connectivity of dorsomedial frontal cortex–lateral frontal cortex was compromised in ADHD.

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ADHD showed increased activities in emotional responding areas to positive emotional stimuli.

Practitioner Review: Self-injurious behaviour in children with developmental delay

BACKGROUND

Self-injurious behaviour is shown by a significant minority of children with developmental delay and has a substantial impact on child and carer wellbeing. Characteristics such as a greater degree of intellectual disability, autism spectrum disorder, some genetic syndromes and repetitive and impulsive behaviours are positively associated with self-injury. Prevalence generally increases with age into midadulthood and the behaviour is notably persistent.

SCOPE

In this review, we discuss the dominant causal theory of self-injury which draws on the principles of operant learning. We evaluate the utility of this theory to account for all empirical observations of self-injury.

FINDINGS

A model of self-injury is presented that extends a previous model described by Guess and Carr. The new model integrates child characteristics and operant learning principles in a phenotype × environment paradigm to explain the variance in developmental trajectory of the severity of self-injury.

CONCLUSIONS

Behaviour dysregulation, as evidenced by the associations between self-injury, self-restraint, repetitive and impulsive behaviours, is identified as potentially influencing the severity and persistence of self-injury. Risk markers for self-injury are identified and the extended model indicates points of intervention and highlights the possibility of risk-related, targeted early intervention. The need for increased training of practitioners in the delivery of demonstrably effective interventions for self-injury is identified.

Behavioral disturbance and treatment strategies in Smith-Magenis syndrome

Background

Smith-Magenis syndrome is a complex neurodevelopmental disorder that includes intellectual deficiency, speech delay, behavioral disturbance and typical sleep disorders. Ninety percent of the cases are due to a 17p11.2 deletion encompassing the RAI1 gene; other cases are linked to mutations of the same gene. Behavioral disorders often include outbursts, attention deficit/hyperactivity disorders, self-injury with onychotillomania and polyembolokoilamania (insertion of objects into body orifices), etc. Interestingly, the stronger the speech delay and sleep disorders, the more severe the behavioral issues. Sleep disturbances associate excessive daytime sleepiness with nighttime agitation. They are underpinned by an inversion of the melatonin secretion cycle. However, the combined intake of beta-blockers in the morning and melatonin in the evening may radically alleviate the circadian rhythm problems.

Discussion

Once sleep disorders are treated, the next challenge is finding an effective treatment for the remaining behavioral problems. Unfortunately, there is a lack of objective guidelines. A comprehensive evaluation of such disorders should include sleep disorders, potential causes of pain, neurocognitive level and environment (i.e. family and school). In any case, efforts should focus on improving communication skills, identifying and treating attention deficit/hyperactivity, aggressiveness and anxiety.

Summary

Treatment of Smith-Magenis syndrome is complex and requires a multidisciplinary team including, among others, geneticists, psychiatrists, neuropediatricians/neurologists, somnologists, developmental and behavioral pediatricians, and speech and language therapists.

Reward modulation of cognitive function in adult attention-deficit/hyperactivity disorder: a pilot study on the role of striatal dopamine

Attention-deficit/hyperactivity disorder (ADHD) is accompanied by impairments in cognitive control, such as task-switching deficits. We investigated whether such problems, and their remediation by medication, reflect abnormal reward motivation and associated striatal dopamine transmission in ADHD. We used functional genetic neuroimaging to assess the effects of dopaminergic medication and reward motivation on task-switching and striatal BOLD signal in 23 adults with ADHD, ON and OFF methylphenidate, and 26 healthy controls. Critically, we took into account interindividual variability in striatal dopamine by exploiting a common genetic polymorphism (3'-UTR VNTR) in the DAT1 gene coding for the dopamine transporter. The results showed a highly significant group by genotype interaction in the striatum. This was because a subgroup of patients with ADHD showed markedly exaggerated effects of reward on the striatal BOLD signal during task-switching when they were OFF their dopaminergic medication. Specifically, patients carrying the 9R allele showed a greater striatal signal than healthy controls carrying this allele, whereas no effect of diagnosis was observed in 10R homozygotes. Aberrant striatal responses were normalized when 9R-carrying patients with ADHD were ON medication. These pilot data indicate an important role for aberrant reward motivation, striatal dopamine and interindividual genetic differences in cognitive processes in adult ADHD.

Impaired reward processing in the human prefrontal cortex distinguishes between persistent and remittent attention deficit hyperactivity disorder

Symptoms of attention deficit hyperactivity disorder (ADHD) in children often persist into adulthood and can lead to severe antisocial behavior. However, to-date it remains unclear whether neuro-functional abnormalities cause ADHD, which in turn can then provide a marker of persistent ADHD. Using event-related functional magnetic resonance imaging (fMRI), we measured blood oxygenation level dependent (BOLD) signal changes in subjects during a reversal learning task in which choice of the correct stimulus led to a probabilistically determined 'monetary' reward or punishment. Participants were diagnosed with ADHD during their childhood (N=32) and were paired with age, gender, and education matched healthy controls (N=32). Reassessment of the ADHD group as adults resulted in a split between either persistent (persisters, N=17) or remitted ADHDs (remitters, N=15). All three groups showed significantly decreased activation in the medial prefrontal cortex (PFC) and the left striatum during punished correct responses, however only remitters and controls presented significant psycho-physiological interaction between these fronto-striatal reward and outcome valence networks. Comparing persisters to remitters and controls showed significantly inverted responses to punishment (P<0.05, family-wise error corrected) in left PFC region. Interestingly, the decreased activation shown after punishment was located in different areas of the PFC for remitters compared with controls, suggesting that remitters might have learned compensation strategies to overcome their ADHD symptoms. Thus, fMRI helps understanding the neuro-functional basis of ADHD related behavior differences and differentiates between persistent and remittent ADHD.

Emotional symptoms and their contribution to functional impairment in adults with attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is a severe neurodevelopmental disorder beginning in childhood and consisting of the core symptoms of inattention, hyperactivity, and impulsivity. The disorder is often accompanied by functional impairment in daily life. Research showed that severe impairment cannot be fully explained by the core symptoms of ADHD. Accordingly, emotional symptoms in ADHD and their influence on functional impairment have increasingly become the focus of research in recent years. The aim of the current study was to investigate the relationship between ADHD core symptoms, emotional symptoms, and functional impairment. We assumed that emotional symptoms might form part of adult ADHD and that the connection between ADHD core symptoms and functional impairment may be partly mediated by emotional symptoms. Data of 176 participants from an ADHD Special Consultations Unit were included. Of these participants, 146 were diagnosed with ADHD, while 30 received no such diagnosis. We developed a structural equation model which included core symptoms, emotional symptoms, and four domains of daily impairment (family life, social life, work, and organization). As predicted, results indicate that emotional symptoms are directly linked to adult ADHD and bear a strong negative influence on different domains of daily life. The results of different analyses showed a mediation of the relationship between ADHD core symptoms and impairment through emotional symptoms: While the connection between inattention and work and organization was partly mediated, the connections between impulsivity and family life and between inattention and social life were shown to be fully mediated through emotional symptoms.

The Kind Nature Behind the Unsocial Semblance: ADHD and Justice Sensitivity-A Pilot Study

OBJECTIVE

Although ADHD is largely associated with antisocial behavior, those affected are often said to show pronounced justice sensitivity. To investigate this assumption, the authors compared participants with ADHD with healthy controls.

METHOD

An experimental game was used to investigate decisions associated with social justice. A questionnaire was used to measure four dimensions of justice sensitivity: observer, profiteer, perpetrator, and victim sensitivity.

RESULTS

Participants with ADHD produced higher values in observer and profiteer sensitivity than the control group. There were no differences in perpetrator sensitivity. Questionnaire results reveal that the inattentive subtype exhibited higher justice sensitivity than the hyperactive/impulsive and combined subtypes and the control group on all dimensions.

CONCLUSION

The results confirm that justice sensitivity is indeed more pronounced in people with ADHD, particularly in the inattentive subtype. It is suggested that pronounced justice sensitivity may be a coping strategy for inferring appropriate social behavior.

The Unique and Combined Effects of Reinforcement and Methylphenidate on Temporal Information Processing in Attention-Deficit/Hyperactivity Disorder

Temporal information processing and reward sensitivity are neurocognitive impairments key to attention-deficit/hyperactivity disorder (ADHD). The aim of this study was to examine the unique and combined impact of reinforcement and methylphenidate (MPH) on temporal information processing in children with ADHD. We predicted that both monetary reinforcement and MPH would ameliorate temporal information processing deficits in ADHD, and we expected that the combined effect of reinforcement and MPH would be most beneficial. Forty children (23 with ADHD and 27 typical controls, aged 8-12 y) performed a time production task under 3 conditions: reward, response cost, and feedback only. Children with ADHD also performed the task (in random order) with placebo, a low, a medium, and a high dose of MPH. Dependent variables were time production accuracy and variability. At baseline, children with ADHD displayed poor internal clock functioning compared with controls, as reflected by greater underestimations of the 1-second interval, and they showed poor motor output as reflected by increased timing variability. Reward and response cost improved motor output (timing variability), with similar effects for both groups. Methylphenidate increased performance (timing variability) compared with placebo, with a higher dose showing greater effects. Effect sizes of reinforcement and medication were medium to large. Contrary to expectations, MPH did not add to the reinforcement effect. The results of this study confirm the value of reward and response cost being similar to that of MPH to optimize (timing) performance of children with ADHD.

Reinforcement enhances vigilance among children with ADHD: comparisons to typically developing children and to the effects of methylphenidate

Sustained attention and reinforcement are posited as causal mechanisms in Attention-Deficit/Hyperactivity Disorder (ADHD), but their interaction has received little empirical study. In two studies, we examined the impact of performance-based reinforcement on sustained attention over time, or vigilance, among 9- to 12-year-old children. Study 1 demonstrated the expected vigilance deficit among children with ADHD (n = 25; 12% female) compared to typically developing (TD) controls (n = 33; 22% female) on a standard continuous performance task (CPT). During a subsequent visit, reinforcement improved attention more among children with ADHD than controls. Study 2 examined the separate and combined effects of reinforcement and acute methylphenidate (MPH) on CPT performance in children with ADHD (n = 19; 21% female). Both reinforcement and MPH enhanced overall target detection and attenuated the vigilance decrement that occurred in no-reinforcement, placebo condition. Cross-study comparisons suggested that the combination of MPH and reinforcement eliminated the vigilance deficit in children with ADHD, normalizing sustained attention. This work highlights the clinically and theoretically interesting intersection of reinforcement and sustained attention.

Attention-deficit/hyperactivity disorder symptoms mediate the association between deficits in executive functioning and social impairment in children

We investigated whether symptoms of attention-deficit/hyperactivity disorder (ADHD) are pathways through which deficits in inhibition and working memory are associated with teacher- and parent-rated social impairment in children. Participants were 64 children (55% males; 53% with ADHD) in grades 3-6. Consistent with our hypotheses, the association between inhibition and social impairment was mediated by hyperactivity/impulsivity and the association between working memory and social impairment was mediated by inattention. Support was not obtained for alternative models wherein the association between inhibition and social impairment was mediated by inattention, and the association between working memory and social impairment was mediated by hyperactivity/impulsivity. Further, tests of hierarchical models suggest that neither inhibition nor working memory is primary but, rather, that these cognitive processes are related to one another and that they collectively (but not uniquely) contribute to hyperactivity/impulsivity and inattention. These findings have implications for conceptual models of ADHD, for understanding factors that influence and sustain social impairment among youth with symptoms of the disorder, and for interventions aimed to addressing such impairment.

Suboptimal foraging behavior: a new perspective on gambling

Why do people gamble? Conventional views hold that gambling may be motivated by irrational beliefs, risk-seeking, impulsive temperament, or dysfunction within the same reward circuitry affected by drugs of abuse. An alternate, unexplored perspective is that gambling is an extension of natural foraging behavior to a financial environment. However, when these foraging algorithms are applied to stochastic gambling outcomes, undesirable results may occur. To test this hypothesis, we recruited participants based on their frequency of gambling-yearly (or less), monthly, and weekly-and investigated how gambling frequency related to irrational beliefs, risk-taking/impulsivity, and foraging behavior. We found that increased gambling frequency corresponded to greater gambling-related beliefs, more exploratory choices on an explore/exploit foraging task, and fewer points earned on a Patchy Foraging Task. Gambling-related beliefs negatively related to performance on the Patchy Foraging Task, indicating that individuals with more gambling-related cognitions tended to leave a patch too quickly. This indicates that frequent gamblers have reduced foraging ability to maximize rewards; however, gambling frequency -and by extension, poor foraging ability- was not related to risk-taking or impulsive behavior. These results suggest that gambling reflects the application of a dysfunctional foraging process to financial outcomes.