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

ADHD symptomatology is best conceptualized as a spectrum: a dimensional versus unitary approach to diagnosis

The aim of this paper is to build a case for the utility of conceptualizing ADHD, not as a unitary disorder that contains several subtypes, but rather as a marker of impairment in attention and/or impulsivity that can be used to identify one of several disorders belonging to a spectrum. The literature will be reviewed to provide an overview of what is known about ADHD in terms of heterogeneity in symptomatology, neuropsychology, neurobiology, as well as comorbidity with other diseases and treatment options. The data from these areas of research will be critically analyzed to support the construct of a spectrum of disorders that can capture the great variability that exists between individuals with ADHD and can discriminate between separate disorders that manifest similar symptoms. The symptoms associated with ADHD can be viewed as dimensional markers that point to a spectrum of related disorders that have as part of their characteristics impairments of attention and impulsivity. The spectrum can accommodate symmetrically and asymmetrically comorbid psychiatric disorders associated with ADHD as well as the wide heterogeneity known to be a part of the ADHD disorder. Individuals presenting with impairments associated with ADHD should be treated as having a positive marker for a spectrum disorder that has as part of its characteristics impairments of attention and/or impulsivity. The identification of impairment in attention and/or impulsivity should be a starting point for further testing rather than being an endpoint of diagnosis that results in pharmacological treatment that may or may not be the optimal therapy. Rather than continuing to attribute a large amount of heterogeneity in symptom presentation as well as a high degree of symmetric and asymmetric comorbidity to a single disorder, clinical evaluation should turn to the diagnosis of the type of attentional deficit and/or impulsivity an individual has in order to colocate the individual's disorder on a spectrum that captures the heterogeneity in symptomatology, the symmetrical and asymmetrical comorbidity, as well as subthreshold presentation and other variants often worked into the disorder of ADHD. The spectrum model can accommodate not only the psychophysiological profiles of patients, but is also consistent with what is known about the functional heterogeneity of the prefrontal cortex as well as the construct that cognitive processes are supported by overlapping and collaborative networks.

Neurofeedback as a nonpharmacological treatment for adults with attention-deficit/hyperactivity disorder (ADHD): study protocol for a randomized controlled trial

BACKGROUND

Neurofeedback has been applied effectively in various areas, especially in the treatment of children with attention-deficit/hyperactivity disorder (ADHD). This study protocol is designed to investigate the effect of slow cortical potential (SCP) feedback and a new form of neurofeedback using near-infrared spectroscopy (NIRS) on symptomatology and neurophysiological parameters in an adult ADHD population. A comparison of SCP and NIRS feedback therapy methods has not been previously conducted and may yield valuable findings about alternative treatments for adult ADHD.

METHODS/DESIGN

The outcome of both neurofeedback techniques will be assessed over 30 treatment sessions and after a 6-month follow-up period, and then will be compared to a nonspecific biofeedback treatment. Furthermore, to investigate if treatment effects in this proof-of-principle study can be predicted by specific neurophysiological baseline parameters, regression models will be applied. Finally, a comparison with healthy controls will be conducted to evaluate deviant pretraining neurophysiological parameters, stability of assessment measures, and treatment outcome.

DISCUSSION

To date, an investigation and comparison of SCP and NIRS feedback training to an active control has not been conducted; therefore, we hope to gain valuable insights in effects and differences of these types of treatment for ADHD in adults.

TRIAL REGISTRATION

This study is registered with the German Registry of Clinical Trials: DRKS00006767 , date of registration: 8 October 2014.

Overview of Attention Deficit Hyperactivity Disorder in Young Children

Attention deficit hyperactivity disorder (ADHD) is a complex disorder, which can be seen as a disorder of life time, developing in preschool years and manifesting symptoms (full and/or partial) throughout the adulthood; therefore, it is not surprising that there are no simple solutions. The aim of this paper is to provide a short and concise review which can be used to inform affected children and adults; family members of affected children and adults, and other medical, paramedical, non-medical, and educational professionals about the disorder. This paper has also tried to look into the process of how ADHD develops; what are the associated problems; and how many other children and adults are affected by such problems all over the world basically to understand ADHD more precisely in order to develop a better medical and or non-medical multimodal intervention plan. If preschool teachers and clinicians are aware of what the research tells us about ADHD, the varying theories of its cause, and which areas need further research, the knowledge will assist them in supporting the families of children with ADHD. By including information in this review about the connection between biological behavior, it is hoped that preschool teachers and clinicians at all levels will feel more confident about explaining to parents of ADHD children, and older ADHD children themselves about the probable causes of ADHD.

Aufmerksamkeitstherapie bei Grundschülern

Ziel vorliegender Arbeit war die Evaluation eines neuropsychologischen Gruppentrainings für aufmerksamkeitsgestörte Kinder von sechs bis neun Jahren. In Anlehnung an das etablierte Programm Attentioner ( Jacobs & Petermann, 2013 ) für Kinder mit Aufmerksamkeitsschwierigkeiten wurde der Mini-Attentioner konzipiert, der keine Lese-, Schreib- und Rechenfertigkeiten erfordert. Weitere Modifikationen waren weniger komplexe Trainingsaufgaben, stärkere Unterstützung durch die Eltern sowie ein unmittelbar verstärkendes Response-Cost-Token-System. 59 Familien nahmen am Training teil. Nach dem Training zeigte sich eine signifikante Reduktion der Aufmerksamkeits- und hyperkinetischen Symptomatik der Kinder im Elternurteil mittels FBB-ADHS. Im Vergleich zur Prämessung erhöhte sich die Aufmerksamkeitsleistung der Kinder in allen vier Untertests der KITAP signifikant. Der Mini-Attentioner kann daher als wirksames Verfahren in der Therapie von Aufmerksamkeitsstörungen eingesetzt werden.

Distinct neuropsychological profiles within ADHD: a latent class analysis of cognitive control, reward sensitivity and timing

BACKGROUND

Multiple pathway models of attention deficit hyperactivity disorder (ADHD) suggest that this disorder is the behavioural expression of dysfunction in one of several separable brain systems. One such model focuses on the brain systems underlying cognitive control, timing and reward sensitivity. It predicts separable subgroups among individuals with ADHD, with performance deficits in only one of these domains. We used latent class analysis (LCA) to identify subgroups of individuals with ADHD based on their overall pattern of neuropsychological performance, rather than grouping them based on cut-off criteria. We hypothesized that we would find separable subgroups with deficits in cognitive control, timing and reward sensitivity respectively.

METHOD

Ninety-six subjects with ADHD (of any subtype) and 121 typically developing controls performed a battery assessing cognitive control, timing and reward sensitivity. LCA was used to identify subgroups of individuals with ADHD with a distinct neuropsychological profile. A similar analysis was performed for controls.

RESULTS

Three subgroups represented 87% of subjects with ADHD. Two of our three hypothesized subgroups were identified, with poor cognitive control and timing. Two of the ADHD subgroups had similar profiles to control subgroups, whereas one subgroup had no equivalent in controls.

CONCLUSIONS

Our findings support multiple pathway models of ADHD, as we were able to define separable subgroups with differing cognitive profiles. Furthermore, we found both quantitative and qualitative differences from controls, suggesting that ADHD may represent both categorical and dimensional differences. These results show that by addressing heterogeneity in ADHD, we can identify more homogeneous subsets of individuals to further investigate.

Mechanisms of impulsive choice: II. Time-based interventions to improve self-control

Impulsive choice behavior has been proposed as a primary risk factor for other maladaptive behaviors (e.g., gambling, substance abuse). Recent research has suggested that timing processes may play a key role in impulsive choice behavior, and could provide an avenue for altering impulsive choice. Accordingly, the current experiments assessed a set of time-based behavioral interventions to increase self-control while simultaneously assessing effects on timing processes within the impulsive choice task. Three experiments assessed temporal interventions using a differential reinforcement of low rates task (Experiment 1) and exposure to either a variable or fixed interval schedule (Experiments 2-3). The efficacy of the interventions was assessed in Sprague-Dawley (Experiments 1-2) and Lewis (Experiment 3) rat strains. Impulsive choice behavior was assessed by measuring preferences of a smaller-sooner (SS) versus a larger-later (LL) reward, while timing of the SS and LL durations was measured during peak trials within the impulsive choice procedure. The rats showed an increased preference for the LL following all three time-based interventions and also displayed increased temporal precision. These results add to the increasing evidence that supports a possible role for temporal processing in impulsive choice behavior and supply novel behavioral interventions to decrease impulsive behavior.

Impaired reward processing by anterior cingulate cortex in children with attention deficit hyperactivity disorder

Decades of research have examined the neurocognitive mechanisms of cognitive control, but the motivational factors underlying task selection and performance remain to be elucidated. We recently proposed that anterior cingulate cortex (ACC) utilizes reward prediction error signals carried by the midbrain dopamine system to learn the value of tasks according to the principles of hierarchical reinforcement learning. According to this position, disruption of the ACC-dopamine interface can disrupt the selection and execution of extended, task-related behaviors. To investigate this issue, we recorded the event-related brain potential (ERP) from children with attention deficit hyperactivity disorder (ADHD), which is strongly associated with ACC-dopamine dysfunction, and from typically developing children while they navigated a simple "virtual T-maze" to find rewards. Depending on the condition, the feedback stimuli on each trial indicated that the children earned or failed to earn either money or points. We found that the reward positivity, an ERP component proposed to index the impact of dopamine-related reward signals on ACC, was significantly larger with money feedback than with points feedback for the children with ADHD, but not for the typically developing children. These results suggest that disruption of the ACC-dopamine interface may underlie the impairments in motivational control observed in childhood ADHD.

Canine-assisted therapy for children with ADHD: preliminary findings from the positive assertive cooperative kids study

OBJECTIVE

The objective of this study was to provide preliminary findings from an ongoing randomized clinical trial using a canine-assisted intervention (CAI) for 24 children with ADHD.

METHOD

Project Positive Assertive Cooperative Kids (P.A.C.K.) was designed to study a 12-week cognitive-behavioral intervention delivered with or without CAI. Children were randomly assigned to group therapy with or without CAI. Parents of children in both groups simultaneously participated in weekly parent group therapy sessions.

RESULTS

Across both treatment groups, parents reported improvements in children's social skills, prosocial behaviors, and problematic behaviors. In both groups, the severity of ADHD symptoms declined during the course of treatment; however, children who received the CAI model exhibited greater reductions in the severity of ADHD symptoms than did children who received cognitive-behavioral therapy without CAI.

CONCLUSION

Results suggest that CAI offers a novel therapeutic strategy that may enhance cognitive-behavioral interventions for children with ADHD.

Spontaneous activity in the waiting brain: a marker of impulsive choice in attention-deficit/hyperactivity disorder?

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In controls very low frequency (VLF) EEG attenuated during task and waiting periods.

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In ADHD there was less attenuation during tasks and none at all during waiting.

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Degree of waiting attenuation correlated with parent's ratings of impulsive choice.

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Aberrant waiting VLF EEG may be a neural marker for impulsive choice in ADHD.

Background

Spontaneous very low frequency oscillations (VLFO), seen in the resting brain, are attenuated when individuals are working on attention demanding tasks or waiting for rewards (Hsu et al., 2013). Individuals with attention-deficit/hyperactivity disorder (ADHD) display excess VLFO when working on attention tasks. They also have difficulty waiting for rewards. Here we examined the waiting brain signature in ADHD and its association with impulsive choice.

Methods

DC-EEG from 21 children with ADHD and 21 controls (9–15 years) were collected under four conditions: (i) resting; (ii) choosing to wait; (iii) being “forced” to wait; and (iv) working on a reaction time task. A questionnaire measured two components of impulsive choice.

Results

Significant VLFO reductions were observed in controls within anterior brain regions in both working and waiting conditions. Individuals with ADHD showed VLFO attenuation while working but to a reduced level and none at all when waiting. A closer inspection revealed an increase of VLFO activity in temporal regions during waiting. Excess VLFO activity during waiting was associated with parents’ ratings of temporal discounting and delay aversion.

Conclusions

The results highlight the potential role for waiting-related spontaneous neural activity in the pathophysiology of impulsive decision-making of ADHD.

Functional dysconnectivity of corticostriatal circuitry and differential response to methylphenidate in youth with attention-deficit/hyperactivity disorder

BACKGROUND

Brain frontostriatal circuits have been implicated in the pathophysiology of attention-deficit/hyperactivity disorder (ADHD). However, effects of methylphenidate on circuit-level functional connectivity are as yet unclear. The aim of the present study was to comprehensively investigate the functional connectivity of major striatal subregions in children with ADHD, including subanalyses directed at mapping cognitive and treatment response characteristics.

METHODS

Using a comprehensive seeding strategy, we examined resting-state functional connectivity of dorsal and ventral subdivisions of the caudate nucleus and putamen in children and adolescents with ADHD and in age- and sex-matched healthy controls.

RESULTS

We enrolled 83 patients with ADHD and 22 controls in our study. Patients showed significantly reduced dorsal caudate functional connectivity with the superior and middle prefrontal cortices as well as reduced dorsal putamen connectivity with the parahippocampal cortex. These connectivity measures were correlated in opposite directions in patients and controls with attentional performance, as assessed using the Continuous Performance Test. Patients showing a good response to methylphenidate had significantly reduced ventral caudate/nucleus accumbens connectivity with the inferior frontal cortices compared with poor responders.

LIMITATIONS

Possible confounding effects of age-related functional connectivity change were not excluded owing to the wide age range of participants.

CONCLUSION

We observed a region-specific effect of methylphenidate on resting-state functional connectivity, suggesting the pretreatment level of ventral frontostriatal functional connectivity as a possible methylphenidate response biomarker of ADHD.

Mechanisms of Individual Differences in Impulsive and Risky Choice in Rats

Individual differences in impulsive and risky choice are key risk factors for a variety of maladaptive behaviors such as drug abuse, gambling, and obesity. In our rat model, ordered individual differences are stable across choice parameters, months of testing, and span a broad spectrum, suggesting that rats, like humans, exhibit trait-level impulsive and risky choice behaviors. In addition, impulsive and risky choices are highly correlated, suggesting a degree of correlation between these two traits. An examination of the underlying cognitive mechanisms has suggested an important role for timing processes in impulsive choice. In addition, in an examination of genetic factors in impulsive choice, the Lewis rat strain emerged as a possible animal model for studying disordered impulsive choice, with this strain demonstrating deficient delay processing. Early rearing environment also affected impulsive behaviors, with rearing in an enriched environment promoting adaptable and more self-controlled choices. The combined results with impulsive choice suggest an important role for timing and reward sensitivity in moderating impulsive behaviors. Relative reward valuation also affects risky choice, with manipulation of objective reward value (relative to an alternative reference point) resulting in loss chasing behaviors that predicted overall risky choice behaviors. The combined results are discussed in relation to domain-specific versus domain-general subjective reward valuation processes and the potential neural substrates of impulsive and risky choice.

Impulsivity in cocaine-dependent individuals with and without attention-deficit/hyperactivity disorder

BACKGROUND

Cocaine-dependent individuals (CDI) display increased impulsivity. However, despite its multifactorial nature most studies in CDI have treated impulsivity monolithically. Moreover, the impact of attention-deficit/hyperactivity disorder (ADHD) has often not been taken into account. This study investigates whether CDI with ADHD (CDI+ADHD) differ from CDI without an ADHD diagnosis and healthy controls (HC) on several impulsivity measures.

METHODS

Thirty-four CDI, 25 CDI+ADHD and 28 HC participated in this study. Trait impulsivity was assessed with the motor, attentional and non-planning subscales of the Barratt Impulsiveness Scale (BIS-11). Neurocognitive dimensions of impulsivity were examined with the stop signal task (SST), delay discounting task (DDT) and information sampling task (IST).

RESULTS

Relative to HC, both CDI and CDI+ADHD scored higher on all BIS-11 subscales, required more time to inhibit their responses (SST) and sampled less information before making a decision (IST). Greater discounting of delayed rewards (DDT) was only found among CDI+ADHD. Compared to CDI without ADHD, CDI+ADHD scored higher on the BIS-11 non-planning and total scale and showed higher discounting rates.

CONCLUSION

CDI score higher on several indices of impulsivity relative to HC, regardless of whether they have concomitant ADHD or not. CDI+ADHD are specifically characterized by a lack of future orientation compared to CDI without ADHD. © 2015 S. Karger AG, Basel.

Functional plasticity in childhood brain disorders: when, what, how, and whom to assess

At every point in the lifespan, the brain balances malleable processes representing neural plasticity that promote change with homeostatic processes that promote stability. Whether a child develops typically or with brain injury, his or her neural and behavioral outcome is constructed through transactions between plastic and homeostatic processes and the environment. In clinical research with children in whom the developing brain has been malformed or injured, behavioral outcomes provide an index of the result of plasticity, homeostasis, and environmental transactions. When should we assess outcome in relation to age at brain insult, time since brain insult, and age of the child at testing? What should we measure? Functions involving reacting to the past and predicting the future, as well as social-affective skills, are important. How should we assess outcome? Information from performance variability, direct measures and informants, overt and covert measures, and laboratory and ecological measures should be considered. In whom are we assessing outcome? Assessment should be cognizant of individual differences in gene, socio-economic status (SES), parenting, nutrition, and interpersonal supports, which are moderators that interact with other factors influencing functional outcome.

Slow cortical potential neurofeedback and self-management training in outpatient care for children with ADHD: study protocol and first preliminary results of a randomized controlled trial

Background: Treatment for children with attention deficit/hyperactivity disorder (ADHD) today is predominantly pharmacological. While it is the most common treatment, it might not always be the most appropriate one. Moreover, long term effects remain unclear. Behavior therapy (BT) and non-pharmacological treatments such as neurofeedback (NF) are promising alternatives, though there are no routine outpatient care/effectiveness studies yet that have included children with medication or changes in medication.

Methods/design: This paper presents the protocol of a randomized controlled trial to compare the effectiveness of a Slow Cortical Potential (SCP) NF protocol with self-management (SM) in a high frequent outpatient care setting. Both groups (NF/SM) receive a total of 30 high frequent therapy sessions. Additionally, 6 sessions are reserved for comorbid problems. The primary outcome measure is the reduction of ADHD core symptoms according to parent and teacher ratings.

Preliminary Results: Untill now 58 children were included in the study (48 males), with a mean age of 8.42 (1.34) years, and a mean IQ of 110 (13.37). Conners-3 parent and teacher ratings were used to estimate core symptom change. Since the study is still ongoing, and children are in different study stages, pre-post and follow-up results are not yet available for all children included. Preliminary results suggest overall good pre-post effects, though. For parent and teacher ratings an ANOVA with repeated measures yielded overall satisfying pre-post effects (η² 0.175–0.513). Differences between groups (NF vs. SM) could not yet be established (p = 0.81).

Discussion: This is the first randomized controlled trial to test the effectiveness of a NF protocol in a high frequent outpatient care setting that does not exclude children on or with changes in medication. First preliminary results show positive effects. The rationale for the trial, the design, and the strengths and limitations of the study are discussed.

Trial registration: This trial is registered in www.clinicaltrials.gov as NCT01879644.

Dissociable effects of game elements on motivation and cognition in a task-switching training in middle childhood

Although motivational reinforcers are often used to enhance the attractiveness of trainings of cognitive control in children, little is known about how such motivational manipulations of the setting contribute to separate gains in motivation and cognitive-control performance. Here we provide a framework for systematically investigating the impact of a motivational video-game setting on the training motivation, the task performance, and the transfer success in a task-switching training in middle-aged children (8-11 years of age). We manipulated both the type of training (low-demanding/single-task training vs. high-demanding/task-switching training) as well as the motivational setting (low-motivational/without video-game elements vs. high-motivational/with video-game elements) separately from another. The results indicated that the addition of game elements to a training setting enhanced the intrinsic interest in task practice, independently of the cognitive demands placed by the training type. In the task-switching group, the high-motivational training setting led to an additional enhancement of task and switching performance during the training phase right from the outset. These motivation-induced benefits projected onto the switching performance in a switching situation different from the trained one (near-transfer measurement). However, in structurally dissimilar cognitive tasks (far-transfer measurement), the motivational gains only transferred to the response dynamics (speed of processing). Hence, the motivational setting clearly had a positive impact on the training motivation and on the paradigm-specific task-switching abilities; it did not, however, consistently generalize on broad cognitive processes. These findings shed new light on the conflation of motivation and cognition in childhood and may help to refine guidelines for designing adequate training interventions.

Thalamic alterations in preterm neonates and their relation to ventral striatum disturbances revealed by a combined shape and pose analysis

Finding the neuroanatomical correlates of prematurity is vital to understanding which structures are affected, and to designing efficient prevention and treatment strategies. Converging results reveal that thalamic abnormalities are important indicators of prematurity. However, little is known about the localization of the abnormalities within the subnuclei of the thalamus, or on the association of altered thalamic development with other deep gray matter disturbances. Here, we aim to investigate the effect of prematurity on the thalamus and the putamen in the neonatal brain, and further investigate the associated abnormalities between these two structures. Using brain structural magnetic resonance imaging, we perform a novel combined shape and pose analysis of the thalamus and putamen between 17 preterm (41.12 ± 5.08 weeks) and 19 term-born (45.51 ± 5.40 weeks) neonates at term equivalent age. We also perform a set of correlation analyses between the thalamus and the putamen, based on the surface and pose results. We locate significant alterations on specific surface regions such as the anterior and ventral anterior (VA) thalamic nuclei, and significant relative pose changes of the left thalamus and the right putamen. In addition, we detect significant association between the thalamus and the putamen for both surface and pose parameters. The regions that are significantly associated include the VA, and the anterior and inferior putamen. We detect statistically significant surface deformations and pose changes on the thalamus and putamen, and for the first time, demonstrate the feasibility of using relative pose parameters as indicators for prematurity in neonates. Our methods show that regional abnormalities of the thalamus are associated with alterations of the putamen, possibly due to disturbed development of shared pre-frontal connectivity. More specifically, the significantly correlated regions in these two structures point to frontal-subcortical pathways including the dorsolateral prefrontal-subcortical circuit, the lateral orbitofrontal-subcortical circuit, the motor circuit, and the oculomotor circuit. These findings reveal new insight into potential subcortical structural covariates for poor neurodevelopmental outcomes in the preterm population.

Attention-deficit hyperactivity disorder (ADHD): an updated review of the essential facts

Attention-deficit hyperactivity disorder (ADHD) is a complex disorder that can affect individuals across the lifespan. It is associated with substantial heterogeneity in terms of aetiology, clinical presentation and treatment outcome and is the subject of extensive research. Because of this, it can be difficult for clinicians to stay up to date with the most relevant findings and know how best to respond to parents' questions and concerns about the disorder and interventions. This is a narrative review that aims to summarize key findings from recent research into ADHD and its treatment that clinicians can share with families in order to increase their knowledge about ADHD and intervention options. ADHD develops as a result of complex interplay between interdependent genetic and non-genetic factors. The disorder is associated with substantial impairments in functioning and poor long-term outcomes. Pharmacological and non-pharmacological treatment options are available for symptom management and to improve function, but functioning outcomes often fail to normalize in children with ADHD. Despite extensive advances in understanding this complex disorder, it is clear that there is still a long way to go. In particular, we address the need for future non-pharmacological interventions to be more specifically targeted for ADHD symptoms and its commonly associated functioning deficits in order to ensure the best long-term outcomes for children with ADHD.

Effects of methylphenidate on cognitive functions in children and adolescents with attention-deficit/hyperactivity disorder: evidence from a systematic review and a meta-analysis

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is associated with a broad range of neuropsychological impairments. The relationship between these neuropsychological deficits and the defining symptoms of ADHD seems more complex than originally thought. Methylphenidate (MPH) is an effective treatment for ADHD symptoms, but its impact on cognition is less clearly understood.

METHODS

With a common systematic search strategy and a rigorous coding and data extraction strategy across domains, we searched electronic databases to identify published placebo controlled trials that compared MPH and placebo on executive and nonexecutive memory, reaction time, reaction time variability and response inhibition in children and adolescents (5-18 years) with a formal diagnosis of ADHD.

RESULTS

Sixty studies were included in the review, of which 36 contained sufficient data for meta-analysis. Methylphenidate was superior to placebo in all five meta-analyses: executive memory, standardized mean difference (SMD) .26, 95% confidence interval (CI): -.39 to -.13; non-executive memory, SMD .60, 95% CI: -.79 to -.41; reaction time, SMD .24, 95% CI: -.33 to -.15; reaction time variability, SMD .62, 95% CI: -.90 to -.34; response inhibition, SMD .41, 95% CI: -.55 to -.27.

CONCLUSIONS

These data support the potentially important effects of MPH on various aspects of cognition known to be associated with ADHD. Consideration should be given to adding cognitive outcomes to the assessment of treatment outcome in ADHD, considering the complexity of the relationship between ADHD symptoms and cognition.

Using stimulants to treat ADHD-related emotional lability

Emotional lability, or sudden strong shifts in emotion, commonly occurs in youth with attention-deficit/hyperactivity disorder. Although these symptoms are impairing and disruptive, relatively little research has addressed their treatment, likely due to the difficulty of reliable and valid assessment. Promising signals for symptom improvement have come from recent studies using stimulants in adults, children and adolescents. Similarly, neuroimaging studies have begun to identify neurobiological mechanisms underlying stimulants' impact on emotion regulation capacities. Here, we review these recent clinical and neuroimaging findings, as well as neurocognitive models for emotional lability in ADHD, issues of relevance to prescribers and the important role of psychiatric comorbidity with treatment choices.

Computer-based cognitive training for ADHD: a review of current evidence

There has been an increasing interest in and the use of computer-based cognitive training as a treatment of attention-deficit/hyperactivity disorder (ADHD). The authors' review of current evidence, based partly on a stringent meta-analysis of 6 randomized controlled trials (RCTs) published in 2013, and an overview of 8 recently published RCTs highlights the inconsistency of findings between trials and across blinded and nonblinded ADHD measures within trials. Based on this, they conclude that more evidence from well-blinded studies is required before cognitive training can be supported as a frontline treatment of core ADHD symptoms.

Relationship among attention-deficit hyperactivity disorder, dietary behaviours and obesity

BACKGROUND

Attention-deficit hyperactivity disorder (ADHD) is one of the most common psychiatric disorders of childhood and can be associated with obesity. The aim of this study was to reveal the connection between ADHD symptoms, food habits and obesity.

METHODS

We examined 12 350 children (6010 boys, 6340 girls) from 27 elementary schools in Cheonan, the Republic of Korea. The study subjects were 5- to 13-year-old children (9.4 ± 1.7 years). Parents completed the DuPaul ADHD Rating Scale. Food habits were measured by a questionnaire adapted from the Korea Youth Risk Behavior Web-based Survey and a validated mini-dietary assessment tool. The full set of hypothesized associations was tested using covariance structural modelling.

RESULTS

The prevalence of ADHD was 7.6% and that of obesity was 4.5% in our study population. The data was well fit by the model. ADHD was associated with body mass index (BMI; standardized β = 0.086, P < 0.001). Bulimic dietary behaviours was related to BMI (standardized β = 0.548, P < 0.001). Socio-economic status was associated with BMI (standardized β = -0.017, P = 0.027).

CONCLUSION

Our analysis suggested that ADHD was a risk factor for obesity through dietary behavioural change and socio-economic status.

Video game performances are preserved in ADHD children compared with controls

OBJECTIVE

Although ADHD and excessive video game playing have received some attention, few studies have explored the performances of ADHD children when playing video games. The authors hypothesized that performances of ADHD children would be as good as those of control children in motivating video games tasks but not in the Continuous Performance Test II (CPT II).

METHOD

The sample consisted of 26 ADHD children and 16 control children. Performances of ADHD and control children were compared on three commercially available games, on the repetition of every game, and on the CPT II.

RESULTS

ADHD children had lower performances on the CPT II than did controls, but they exhibited equivalent performances to controls when playing video games at both sessions and on all three games.

CONCLUSION

When playing video games, ADHD children present no difference in inhibitory performances compared with control children. This demonstrates that cognitive difficulties in ADHD are task dependent.

Volumetric MRI differences in treatment naïve and chronically treated adolescents with ADHD-combined type

OBJECTIVE

The purpose of this study was to determine whether there are differences in the volume of specific brain regions using magnetic resonance imaging (MRI) between children and adolescents with ADHD and controls and whether such differences are related to the participants' history of stimulant treatment.

METHOD

A total of 16 healthy controls, 16 children, and adolescents with ADHD-combined (ADHD-C) type with a history of stimulant treatment, and 13 children and adolescents with ADHD-C type treatment naïve participated.

RESULTS

Total frontal, prefrontal, and caudate volumes were larger for children and adolescents with ADHD compared with controls with no differences based on medication history with larger right gray and white matter prefrontal volumes in the ADHD groups. A medication difference was found with the right anterior cingulate cortex smaller in children and adolescents without a treatment history.

CONCLUSION

These findings suggest that aberrant prefrontal and caudate volumes in ADHD-C may compromise functioning of the frontostriatal circuitry.

The neurobiological link between OCD and ADHD

Obsessive compulsive disorder (OCD) and attention deficit hyperactivity disorder (ADHD) are two of the most common neuropsychiatric diseases in paediatric populations. The high comorbidity of ADHD and OCD with each other, especially of ADHD in paediatric OCD, is well described. OCD and ADHD often follow a chronic course with persistent rates of at least 40–50 %. Family studies showed high heritability in ADHD and OCD, and some genetic findings showed similar variants for both disorders of the same pathogenetic mechanisms, whereas other genetic findings may differentiate between ADHD and OCD. Neuropsychological and neuroimaging studies suggest that partly similar executive functions are affected in both disorders. The deficits in the corresponding brain networks may be responsible for the perseverative, compulsive symptoms in OCD but also for the disinhibited and impulsive symptoms characterizing ADHD. This article reviews the current literature of neuroimaging, neurochemical circuitry, neuropsychological and genetic findings considering similarities as well as differences between OCD and ADHD.

ADHD, altered dopamine neurotransmission, and disrupted reinforcement processes: implications for smoking and nicotine dependence

Attention deficit hyperactivity disorder (ADHD) is a common and impairing disorder affecting millions of children, adolescents, and adults. Individuals with ADHD smoke cigarettes at rates significantly higher than their non-diagnosed peers and the disorder also confers risk for a number of related adverse smoking outcomes including earlier age of initiation, faster progression to regular use, heavier smoking/greater dependence, and more difficulty quitting. Progress in our understanding of dopamine neurotransmission and basic behavioral reinforcement processes in ADHD may help increase our understanding of the ADHD-smoking comorbidity. This review will examine how these areas have been studied and how further work may aid in the development of better prevention and treatment for smoking in those with ADHD.

A comprehensive assessment of memory, delay aversion, timing, inhibition, decision making and variability in attention deficit hyperactivity disorder: advancing beyond the three-pathway models

BACKGROUND

Although attention deficit hyperactivity disorder (ADHD) has been associated with a broad range of deficits across various neuropsychological domains, most studies have assessed only a narrow range of neuropsychological functions. Direct cross-domain comparisons are rare, with almost all studies restricted to less than four domains. Therefore, the relationships between these various domains remain undefined. In addition, almost all studies included previously medicated participants, limiting the conclusions that can be drawn. We present the first study to compare a large cohort of medication-naive boys with ADHD with healthy controls on a broad battery of neuropsychological tasks, assessing six key domains of neuropsychological functioning.

METHOD

The neuropsychological functioning of 83 medication-naive boys with well-characterized ADHD (mean age 8.9 years) was compared with that of 66 typically developing (TYP) boys (mean age 9.0 years) on a broad battery of validated neuropsychological tasks.

RESULTS

Data reduction using complementary factor analysis (CFA) confirmed six distinct neuropsychological domains: working memory, inhibition, delay aversion, decision making, timing and response variability. Boys with ADHD performed less well across all six domains although, for each domain, only a minority of boys with ADHD had a deficit [effect size (% with deficit) ADHD versus TYP: working memory 0.95 (30.1), inhibition 0.61 (22.9), delay aversion 0.82 (36.1), decision making 0.55 (20.5), timing 0.71 (31.3), response variability 0.37 (18.1)].

CONCLUSIONS

The clinical syndrome of ADHD is neuropsychologically heterogeneous. These data highlight the complexity of the relationships between the different neuropsychological profiles associated with ADHD and the clinical symptoms and functional impairment.

Neural mechanisms of gain-loss asymmetry in temporal discounting

Humans typically discount future gains more than losses. This phenomenon is referred to as the "sign effect" in experimental and behavioral economics. Although recent studies have reported associations between the sign effect and important social problems, such as obesity and incurring multiple debts, the biological basis for this phenomenon remains poorly understood. Here, we hypothesized that enhanced loss-related neural processing in magnitude and/or delay representation are causes of the sign effect. We examined participants performing intertemporal choice tasks involving future gains or losses and compared the brain activity of those who exhibited the sign effect and those who did not. When predicting future losses, significant differences were apparent between the two participant groups in terms of striatal activity representing delay length and in insular activity representing sensitivity to magnitude. Furthermore, participants with the sign effect exhibited a greater insular response to the magnitude of loss than to that of gain, and also a greater striatal response to the delay of loss than to that of gain. These findings may provide a new biological perspective for the development of novel treatments and preventive measures for social problems associated with the sign effect.

Functional impairments in attention deficit hyperactivity disorder: the mediating role of neuropsychological functioning

Attention deficit hyperactivity disorder (ADHD) is associated with multiple neuropsychological deficits and the present study aimed to investigate to what extent these deficits are related to the functional impairments associated with the disorder. The results showed that all executive functioning deficits and reaction time variability acted as mediators in the relation between ADHD and academic achievement. However, only the effect of working memory for language skills, and the effects of reaction time variability and working memory for mathematics, remained significant when studying independent effects. Regulation of anger was a significant mediator for peer problems. Gender or symptoms of oppositional defiant disorder (ODD) or conduct disorder (CD) did not moderate these findings.

Translational studies of goal-directed action as a framework for classifying deficits across psychiatric disorders

The ability to learn contingencies between actions and outcomes in a dynamic environment is critical for flexible, adaptive behavior. Goal-directed actions adapt to changes in action-outcome contingencies as well as to changes in the reward-value of the outcome. When networks involved in reward processing and contingency learning are maladaptive, this fundamental ability can be lost, with detrimental consequences for decision-making. Impaired decision-making is a core feature in a number of psychiatric disorders, ranging from depression to schizophrenia. The argument can be developed, therefore, that seemingly disparate symptoms across psychiatric disorders can be explained by dysfunction within common decision-making circuitry. From this perspective, gaining a better understanding of the neural processes involved in goal-directed action, will allow a comparison of deficits observed across traditional diagnostic boundaries within a unified theoretical framework. This review describes the key processes and neural circuits involved in goal-directed decision-making using evidence from animal studies and human neuroimaging. Select studies are discussed to outline what we currently know about causal judgments regarding actions and their consequences, action-related reward evaluation, and, most importantly, how these processes are integrated in goal-directed learning and performance. Finally, we look at how adaptive decision-making is impaired across a range of psychiatric disorders and how deepening our understanding of this circuitry may offer insights into phenotypes and more targeted interventions.

Working memory deficits in boys with attention deficit/hyperactivity disorder (ADHD): An examination of orthographic coding and episodic buffer processes

The episodic buffer component of working memory was examined in children with attention deficit/hyperactivity disorder (ADHD) and typically developing peers (TD). Thirty-two children (ADHD = 16, TD = 16) completed three versions of a phonological working memory task that varied with regard to stimulus presentation modality (auditory, visual, or dual auditory and visual), as well as a visuospatial task. Children with ADHD experienced the largest magnitude working memory deficits when phonological stimuli were presented via a unimodal, auditory format. Their performance improved during visual and dual modality conditions but remained significantly below the performance of children in the TD group. In contrast, the TD group did not exhibit performance differences between the auditory- and visual-phonological conditions but recalled significantly more stimuli during the dual-phonological condition. Furthermore, relative to TD children, children with ADHD recalled disproportionately fewer phonological stimuli as set sizes increased, regardless of presentation modality. Finally, an examination of working memory components indicated that the largest magnitude between-group difference was associated with the central executive. Collectively, these findings suggest that ADHD-related working memory deficits reflect a combination of impaired central executive and phonological storage/rehearsal processes, as well as an impaired ability to benefit from bound multimodal information processed by the episodic buffer.

Heroin and amphetamine users display opposite relationships between trait and neurobehavioral dimensions of impulsivity

The multidimensional construct of impulsivity is implicated in all phases of the addiction cycle. Substance dependent individuals (SDIs) demonstrate elevated impulsivity on both trait and laboratory tests of neurobehavioral impulsivity; however our understanding of the relationship between these different aspects of impulsivity in users of different classes of drugs remains rudimentary. The goal of this study was to assess for commonalities and differences in the relationships between trait and neurobehavioral impulsivity in heroin and amphetamine addicts. Participants included 58 amphetamine dependent (ADIs) and 74 heroin dependent individuals (HDIs) in protracted abstinence. We conducted Principal Component Analyses (PCA) on two self-report trait and six neurobehavioral measures of impulsivity, which resulted in two trait impulsivity (action, planning) and four neurobehavioral impulsivity composites (discriminability, response inhibition efficiency, decision-making efficiency, quality of decision-making). Multiple regression analyses were used to determine whether neurobehavioral impulsivity is predicted by trait impulsivity and drug type. The analyses revealed a significant interaction between drug type and trait action impulsivity on response inhibition efficiency, which showed opposite relationships for ADIs and HDIs. Specifically, increased trait action impulsivity was associated with worse response inhibition efficiency in ADIs, but with better efficiency in HDIs. These results challenge the unitary account of drug addiction and contribute to a growing body of literature that reveals important behavioral, cognitive, and neurobiological differences between users of different classes of drugs.

Abnormal striatal BOLD responses to reward anticipation and reward delivery in ADHD

Altered reward processing has been proposed to contribute to the symptoms of attention deficit hyperactivity disorder (ADHD). The neurobiological mechanism underlying this alteration remains unclear. We hypothesize that the transfer of dopamine release from reward to reward-predicting cues, as normally observed in animal studies, may be deficient in ADHD. Functional magnetic resonance imaging (fMRI) was used to investigate striatal responses to reward-predicting cues and reward delivery in a classical conditioning paradigm. Data from 14 high-functioning and stimulant-naïve young adults with elevated lifetime symptoms of ADHD (8 males, 6 females) and 15 well-matched controls (8 males, 7 females) were included in the analyses. During reward anticipation, increased blood-oxygen-level-dependent (BOLD) responses in the right ventral and left dorsal striatum were observed in controls, but not in the ADHD group. The opposite pattern was observed in response to reward delivery; the ADHD group demonstrated significantly greater BOLD responses in the ventral striatum bilaterally and the left dorsal striatum relative to controls. In the ADHD group, the number of current hyperactivity/impulsivity symptoms was inversely related to ventral striatal responses during reward anticipation and positively associated with responses to reward. The BOLD response patterns observed in the striatum are consistent with impaired predictive dopamine signaling in ADHD, which may explain altered reward-contingent behaviors and symptoms of ADHD.

Attention-deficit/hyperactivity disorder and sluggish cognitive tempo dimensions in relation to executive functioning in adolescents with ADHD

Previous research has failed to find a consistent relation between Sluggish Cognitive Tempo (SCT) and executive function (EF) in youth with Attention-Deficit/Hyperactivity Disorder (ADHD) when laboratory-based neuropsychological tasks of EF are used, whereas recent research with youth and adults suggests a significant relation between SCT and ratings of EF. The purpose of this study was to examine ADHD dimensions and SCT symptoms in relation to ratings of EF in adolescents with ADHD. Fifty-two adolescents (ages 12-16; 70 % male) participated in this study. Parents and teachers completed validated measures of SCT, ADHD symptoms, and EF in daily life. Adolescents' intelligence and academic achievement were also assessed. ADHD and SCT symptoms were significantly correlated with ratings of EF. Regression analyses demonstrated that, as hypothesized, ADHD hyperactive-impulsive symptoms were strongly associated with behavioral regulation EF deficits, with ADHD inattentive and SCT symptoms unrelated to behavioral regulation EF when hyperactive-impulsivity symptoms were included in the model. The parent-reported SCT Slow scale measuring motivation, initiative, and apathy predicted both parent- and teacher-reported metacognitive EF deficits above and beyond youth characteristics and ADHD symptoms. In contrast, teacher-reported ADHD inattention was most clearly associated with teacher-reported metacognitive EF deficits. This study provides preliminary evidence for the importance of SCT symptoms in relation to metacognitive EF deficits among adolescents with ADHD and the need to further investigate the overlap and distinctiveness of SCT/ADHD. Further research is needed to replicate and extend these findings.

Developments and challenges in the diagnosis and treatment of ADHD

Attention-deficit/hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder, often associated with other psychiatric comorbidities, functional impairments, and poor long-term outcomes. The objective of this selected review is to describe current advances and challenges in the diagnosis and treatment of ADHD. The disorder is associated with neurobiological underpinnings and is highly heterogeneous in various aspects, such as symptom profiles, cognitive impairments, and neurobiological and genetic features. The efficacy and safety of short-term pharmacological treatments across the life cycle is well studied, but further research investigating long-term treatment, impact of treatment in preschoolers, and non-pharmacological interventions is needed. Future research is also needed to better characterize the neurodevelopmental pathways of the disorder, linking clinical and neurobiological information, less investigated populations, and new interventions.

Selbstregulation, Lageorientierung und Aufmerksamkeit bei erwachsenen ADHS-Patienten

Einleitung: Es wurden Selbststeuerungskompetenzen und der Einfluss der Unaufmerksamkeit auf die Selbststeuerung bei Erwachsenen mit einer Aufmerksamkeits-Defizit/Hyperaktivitätsstörung (ADHS) untersucht. Methode: Erwachsene mit ADHS und gesunde Kontrollen füllten die Kurzversion des Selbststeuerungs-Inventars (SSI-K) und den Fragebogen zur Messung der Handlungskontrolle (HAKEMP 90) aus. Die Beeinträchtigungen der Aufmerksamkeit wurden bei den ADHS-Patienten mittels entsprechenden Subskalen aus dem ADHS-Selbstbeurteilungsbogen (ADHS-SB) und den Conners Adult ADHD Rating Scales (CAARS-R) erfasst. Mittels Kovarianzanalyse wurden Gruppenunterschiede in der Selbststeuerung zwischen ADHS-Patienten und Kontrollpersonen untersucht. Als nächster Schritt wurde der Zusammenhang zwischen Selbststeuerung und Unaufmerksamkeit bei ADHS-Patienten anhand einer einfachen linearen Regression überprüft. Ergebnisse und Schlussfolgerung: Erwachsene mit ADHS zeichnen sich durch eine geringe Selbstmotivation, eine stärkere Hemmung der willentlichen Prozesse in Form von Willenshemmung und Selbsthemmung, sowie einer Disposition zur Lageorientierung aus. Die Beeinträchtigung der Aufmerksamkeit bei der ADHS-Gruppe scheint die Willenshemmung zu begünstigen.

Attention deficit hyperactivity disorder

Over the last two decades, there have been numerous technical and methodological advances available to clinicians and researchers to better understand attention deficit hyperactivity disorder (ADHD) and its etiology. Despite the growing body of literature investigating the disorder's pathophysiology, ADHD remains a complex psychiatric disorder to characterize. This chapter will briefly review the literature on ADHD, with a focus on its history, the current genetic insights, neurophysiologic theories, and the use of neuroimaging to further understand the etiology. We address some of the major concerns that remain unclear about ADHD, including subtype instability, heterogeneity, and the underlying neural correlates that define the disorder. We highlight that the field of ADHD is rapidly evolving; the descriptions provided here will hopefully provide a sturdy foundation for which to build and improve our understanding of the disorder.

Imaging genetics in adult attention-deficit/hyperactivity disorder (ADHD): a way towards pathophysiological understanding?

Attention-deficit/hyperactivity disorder (ADHD) is a common, early-onset and enduring developmental disorder whose underlying etiological and neurobiological processes are the current focus of major research. Research strategies have made considerable effort in elucidating the complex genetic architecture of ADHD and indicate various pathways from genotype to phenotype. Understanding ADHD as a neuropsychiatric disorder enabled to investigate markers of neural activity as endophenotypes to better explain the link from gene to symptomatology (the so-called imaging genetics approach). Overcoming the originally rather restrictive requirements for an endophenotype, imaging genetics studies are supposed to offer a much more flexible and hypothesis-driven approach towards the etiology of ADHD. Although 1) ADHD often persists into adulthood, thus remaining a prevalent disorder, and 2) imaging genetics provides a promising research approach, a review on imaging genetics in adult ADHD - as available for childhood ADHD (Durston 2010) - is lacking. In this review, therefore, findings from the few available imaging genetics studies in adult ADHD will be summarized and complemented by relevant findings from healthy controls and children with ADHD that are considered important for the adult ADHD imaging genetics approach. The studies will be reviewed regarding implications for basic research and possible practical applications. Imaging genetics studies in adult ADHD have the potential to further clarify pathophysiological pathways and mechanisms, to derive new testable hypotheses, to investigate genetic interaction effects and to partly influence practical applications. In combination with other research strategies, they can incrementally foster the understanding of relevant processes in a more comprehensive way. Current limitations comprise the incapability to discover new genes, a high genetic load in patients potentially obscuring the effect of single candidate genes, the mostly unknown heritability of the endophenotype and the heterogeneous manifestation of ADHD.

Behavioral and neurophysiological study of attentional and inhibitory processes in ADHD-combined and control children

This study compares behavioral and electrophysiological (P300) responses recorded in a cued continuous performance task (CPT-AX) performed by children with attention deficit hyperactivity disorder-combined subtype (ADHD-com) and age-matched healthy controls. P300 cognitive-evoked potentials and behavioral data were recorded in eight children with ADHD (without comorbidity) and nine control children aged 8-12 years while performing a CPT-AX task. Such task enables to examine several kinds of false alarms and three different kinds of P300 responses: the "Cue P300", the "Go P300" and the "NoGo P300", respectively, associated with preparatory processing/attentional orienting, motor/response execution and motor/response inhibition. Whereas hit rates were about 95% in each group, ADHD children made significantly more false alarm responses (inattention- and inhibition-related) than control children. ADHD children had a marginally smaller Cue P300 than the control children. Behavioral and electrophysiological findings both highlighted inhibition and attention deficits in ADHD-com children in the CPT-AX task. A rarely studied kind of false alarm, the "Other" FA, seems to be a sensitive FA to take into account, even if its interpretation remains unclear.

Self-inserted foreign body and attention-deficit/hyperactivity disorder: evaluated by the Conners' Parent Rating Scales-Revised

OBJECTIVES

We aimed to evaluate the relationship between attention-deficit/hyperactivity disorder (ADHD) and self-inserted foreign bodies (SIFBs) in children by the Conners' Parent Rating Scales-Revised (CPRS-R).

METHODS

Forty-five children (31 males and 14 females) with self-inserted foreign body of ear/nose and 37 healthy children (22 males and 15 females) included into the study. They were all between 3 and 9 years old. The parents filled the socio-demographic information form including age, gender, demographic data, previous medical history of the child and features of the family; and completed the Conners' Parent Rating Scales-Revised (CPRS-R) questionnaire.

RESULTS

In the SIFB group (study), 55.6% of the children were not attending to the school, 31.1% of them were attending to the primary school and 13.3% of them were the pre-school student. These rates were 37.8%, 32.4% and 29.7%, respectively, in the control group. The all CPRS-R subscale values (CG/I, H, ADHD-I, CGI-DI, DSMIV SS-I, DSM-IV SS-HI and DSM-IV SS-T) were significantly higher in the study group than the control group. There was no significant correlation between gender of the children and CPRS-R subscales. Children with lower school success, and having previous psychiatric problems were related to higher CPRS-R values in all subscales. In older children, hyperactivity scores were lower; and in younger children and the children, not going to the school, hyperactivity scores were higher. CPRS-R scores decreased as the child grown.

CONCLUSION

It was concluded that children with ADHD were more likely to have conditions that might damage himself/herself such as self-inserted foreign body or trauma than normal children. To avoid this condition, these families should closely observe the child; and the child should be provided to participate in activities such as group games and activities that contribute to the development of the child. Warning the children properly and close follow-up of the young children are required to prevent this unwanted condition.

What part of working memory is not working in ADHD? Short-term memory, the central executive and effects of reinforcement

Deficits in Working Memory (WM) are related to symptoms of Attention-Deficit/Hyperactivity Disorder (ADHD). In children with ADHD visuospatial WM is most impaired. WM is composed of Short-Term Memory (STM) and a Central Executive (CE). Therefore, deficits in either or both STM and the CE may account for WM impairments in children with ADHD. WM-component studies investigating this find deficits in both STM and the CE. However, recent studies show that not only cognitive deficits, but also motivational deficits give rise to the aberrant WM performance of children with ADHD. To date, the influence of these motivational deficits on the components of WM has not been investigated. This study examined the effects of a standard (feedback-only) and a high level of reinforcement (feedback + 10 euros) on the visuospatial WM-, visuospatial STM-, and the CE performance of 86 children with ADHD and 62 typically-developing controls. With standard reinforcement the STM, CE, and WM performance of children with ADHD was worse than that of controls. High reinforcement improved STM and WM performance more in children with ADHD than in controls, but was unable to normalize their performance. High reinforcement did not appear to improve the CE-related performance of children with ADHD and controls. Motivational deficits have a detrimental effect on both the visuospatial WM performance and the STM performance of children with ADHD. Aside from motivational deficits, both the visuospatial STM and the CE of children with ADHD are impaired, and give rise to their deficits in visuospatial WM.

Motor cortical inhibition in ADHD: modulation of the transcranial magnetic stimulation-evoked N100 in a response control task

The N100 component, evoked by transcranial magnetic stimulation (TMS) and electroencephalography is associated with the activation of inhibitory cortical circuits and has recently been suggested as a potential marker of inhibition in attention-deficit/hyperactivity disorder (ADHD). The aim of the present ADHD study was to investigate the modulation of the TMS-N100 in go and nogo trials of a response control task considering stages of response preparation, activation, execution and inhibition. Eighteen children with ADHD and 19 typically developing children, aged 10-14 years, were assessed. TMS was delivered over the left motor cortex, the TMS-N100 was measured at electrode P3. The TMS-N100 was determined at rest and at different time points (50 ms before S2; 150, 300 and 500 ms after S2) in a cued go/nogo task (S1-S2 paradigm). Correlations between the TMS-N100 measures, MEP-related TMS measures (e.g., short-interval intracortical inhibition) and performance measures were calculated. At rest, the amplitude of TMS-N100 was not found to be significantly reduced in the ADHD group. During the go/nogo task, children with ADHD showed a smaller increase of TMS-N100 amplitude in go trials and a smaller decrease after inhibiting a response. In go trials, a lower TMS-N100 was associated with a smaller variability of reaction times. A smaller TMS-N100 modulation extends the picture of cortical inhibition deficits in ADHD. Findings suggest a functional involvement of the mechanisms underlying the TMS-N100 at the motor output stage.

A simple behavioral paradigm to measure impulsive behavior in an animal model of attention deficit hyperactivity disorder (ADHD) of the spontaneously hypertensive rats

Impulsiveness is an important component of many psychiatric disorders including Attention-deficit/hyperactivity disorder (ADHD). Although the neurobiological basis of ADHD is unresolved, behavioral tests in animal models have become indispensable tools for improving our understanding of this disorder. In the punishment/extinction paradigm, impulsivity is shown by subjects that persevere with responding despite punishment or unrewarded responses. Exploiting this principle, we developed a new behavioral test that would evaluate impulsivity in the most validated animal model of ADHD of the Spontaneously Hypertensive rat (SHR) as compared with the normotensive “control” strain, the Wistar Kyoto rat (WKY). In this paradigm we call the Electro-Foot Shock aversive water Drinking test (EFSDT), water-deprived rats should pass over an electrified quadrant of the EFSDT apparatus to drink water. We reasoned that impulsive animals show increased frequency to drink water even with the presentation of an aversive consequence (electro-shock). Through this assay, we showed that the SHR was more impulsive than the WKY as it demonstrated more “drinking attempts” and drinking frequency. Methylphenidate, the most widely used ADHD medication, significantly reduced drinking frequency of both SHR and WKY in the EFSDT. Thus, the present assay may be considered as another behavioral tool to measure impulsivity in animal disease models, especially in the context of ADHD.

ADHD Preschoolers with and without ODD: do they act differently depending on degree of task engagement/reward?

OBJECTIVE

To examine the impact of reinforcement on reaction time (RT) and RT variability (RT standard deviation [RTSD]) in preschoolers with ADHD with and without oppositional defiant disorder (ODD), and a typically developing (TD) comparison group.

METHOD

Participants were administered a computerized task consisting of two conditions: simple RT (SRT) and reinforced SRT (SRTr). Data were analyzed using two-way (Group × Condition) mixed ANOVAs and followed-up using pairwise comparisons.

RESULTS

RTs were significantly shorter and less variable during the SRTr than the SRT condition. A significant Group x Condition interaction was observed for RTSD (F= 3.38, p < .05); post hoc analyses indicated that the RTSD of the ADHD + ODD group was significantly more variable than that of the TD group during the SRT condition (F = 4.81, p < .05). However, their RTSD was statistically indistinguishable from the other groups during the SRTr condition.

CONCLUSION

Preschoolers who are oppositional/defiant and hyperactive are the most responsive to feedback/reward.

Spezifische und gemeinsame neuropsychologische Basisdefizite bei ADHS- und ODD-Symptomen im Vorschulalter

Es ist anzunehmen, dass unterschiedliche neuropsychologische Basisdefizite den Symptomen der ADHS zugrunde liegen. Die Frage ist, ob spezielle Basisdefizite spezifisch mit der ADHS-Symptomatik verbunden sind oder auch mit Symptomen einer Störung des Sozialverhaltens mit oppositionellem, aufsässigem Verhalten (ODD) korrelieren. Deswegen wurden neuropsychologische Aufgaben zur Erfassung von exekutiver Inhibitionskontrolle, Verzögerungsaversion, Intelligenz und Sensomotorik mit 141 Kindern (davon 68 Jungen) zwischen drei und sechs Jahren durchgeführt. Eltern (Pre-PACS Interview, SDQ) und Erzieher/innen (SDQ) aus dem Kindergarten schätzten die ADHS- und ODD-Symptome ein. Die ADHS-Symptome korrelierten bei Berücksichtigung von Kontrollvariablen signifikant mit exekutiver Inhibitionskontrolle, Verzögerungsaversion, Intelligenz und Sensomotorik. Bei zusätzlicher Kontrolle der ODD-Symptome zeigten sich weiterhin signifikante Assoziationen mit Verzögerungsaversion und Intelligenz. Auch in der multiplen Regressionsanalyse klärten diese beiden neuropsychologischen Basisdefizite jeweils unabhängig signifikant Varianz der ADHS-Symptome auf. Die ODD-Symptome zeigten keinen über die ADHS-Symptome hinausgehenden Zusammenhang mit den neuropsychologischen Basisdefiziten. ADHS-Symptome im Vorschulalter gehen mit höherer Verzögerungsaversion und Intelligenzdefiziten einher, während ODD-Symptome nicht unabhängig mit neuropsychologischen Basisdefiziten assoziiert sind.

Steep temporal reward discounting in ADHD-Combined type: acting upon feelings

Difficulty waiting plays a primary role in symptoms of attention-deficit/hyperactivity disorder (ADHD), in particular, impulsivity. Current theories suggest that relatively strong preferences for small immediate rewards as observed in ADHD-Combined type are the result of delay-related negative feelings. However, the measurement of difficulty waiting is typically limited to objective choices between small immediate and large delayed rewards. This study aimed at extending the measurement of difficulty waiting in ADHD-Combined type with ratings about subjective feelings. Children and adolescents (ages 6-17) with ADHD-Combined type (n=25), ADHD-Inattentive type (n=20) and matched typically developing participants (n=37) performed temporal reward discounting tasks, and completed a Visual Analogue Scale of subjectively experienced ease/difficulty waiting. Although those with ADHD-Combined type demonstrated relatively steep temporal reward discounting, as reported elsewhere (Scheres et al., 2010), there were no group differences for subjectively experienced ease/difficulty waiting. Additionally, correlations between subjective and objective measures of difficulty waiting were significantly higher in the ADHD-Combined type group than in the control group. These findings suggest that (a) those with ADHD-Combined type do not choose impulsively because they have more negative feelings about waiting than controls; (b) choices in the ADHD-Combined type group are more in accordance with/driven by their feelings than choices made by participants in the control group.

Self-regulation strategies support children with ADHD to overcome symptom-related behavior in the classroom

Children with attention deficit hyperactivity disorder (ADHD) suffer from self-regulation deficits that cause inattention, impulsivity, and hyperactivity. Self-regulation interventions may address these deficits, but to date, only few empirical studies have examined their benefits for children with ADHD in everyday life. The present study investigated three classroom interventions to promote self-regulation and tested their benefit on self-regulatory competencies (assessed with an ADHD questionnaire) in children with ADHD. Students of a special education school for children with ADHD participated in the intervention study that included three sessions (Session 1: Goal Intention or Goal Intention + If-Then Plan; Session 2: Goal Intention + If-Then Plan; Session 3: Goal Intention + If-Then Plan + Self-Monitoring). Teacher-rated self-regulatory competencies were assessed both before and after the intervention sessions. Children with ADHD had better self-regulatory competencies after their first Goal Intention + If-Then Plan Session, but lasting intervention effects were found only when children started with a mere goal intention session.

Risky behavior in gambling tasks in individuals with ADHD--a systematic literature review

OBJECTIVE

The aim of this review was to gain insight into the relationship between Attention deficit hyperactivity disorder (ADHD) and risky performance in gambling tasks and to identify any potential alternate explanatory factors.

METHODS

PsycINFO, PubMed, and Web of Knowledge were searched for relevant literature comparing individuals with ADHD to normal controls (NCs) in relation to their risky performance on a gambling task. In total, fourteen studies in children/adolescents and eleven studies in adults were included in the review.

RESULTS

Half of the studies looking at children/adolescents with ADHD found evidence that they run more risks on gambling tasks when compared to NCs. Only a minority of the studies on adults with ADHD reported aberrant risky behavior. The effect sizes ranged from small to large for both age groups and the outcome pattern did not differ between studies that applied an implicit or explicit gambling task. Two studies demonstrated that comorbid oppositional defiant disorder (ODD) and conduct disorder (CD) increased risky behavior in ADHD. Limited and/or inconsistent evidence was found that comorbid internalizing disorders (IDs), ADHD subtype, methylphenidate use, and different forms of reward influenced the outcomes.

CONCLUSION

The evidence for increased risky performance of individuals with ADHD on gambling tasks is mixed, but is stronger for children/adolescents with ADHD than for adults with ADHD, which may point to developmental changes in reward and/or penalty sensitivity or a publication bias for positive findings in children/adolescents. The literature suggests that comorbid ODD/CD is a risk factor in ADHD for increased risky behavior. Comorbid IDs, ADHD subtype, methylphenidate use, and the form of reward received may affect risky performance in gambling tasks; however, these factors need further examination. Finally, the implications of the findings for ADHD models and the ecological validity of gambling tasks are discussed.