Inhibition and Attention Deficit Hyperactivity Disorder

This paper updates the author's earlier hypothesis that Attention Deficit Hyperactivity Disorder (ADHD) reflects underactivity in Gray's Behavioral Inhibition System. Five areas of research are reviewed: (1) studies using the stop-signal task, (2) studies of errors of commission, (3) a study of inhibition indexed by eye movements, (4) a neuroimaging study of the corpus callosum, and (5) a study on the prediction of response to methylphenidate. Data from the many different dependent variables in these studies are interpreted as supporting disinhibition as a core deficit in ADHD.     

Children with Attention Deficit Hyperactivity Disorder

ABSTRACT

It is estimated that there have been over 4,000 articles in the literature on the subject of attentional problems, addressing its etiology, epidemiology, assessment, diagnosis, and treatment. This article reviews recent and relevant literature with an eye toward functional conclusions and linkages between assessment and intervention. The article concludes by providing a problem-solving model that integrates parent or teachers' referral concerns, reasons for these concerns, assessment methods, and intervention strategies. In the end, four definitive conclusions are drawn, and the importance of multimodal strategies that collaboratively involve home, school, and community settings is emphasized.     

Task Switching and Attention Deficit Hyperactivity Disorder

The main goal of the present set of studies was to examine the efficiency of executive control processes and, more specifically, the control processes involved in task set inhibition and preparation to perform a new task in attention deficit hyperactivity disorder (ADHD) and non-ADHD children. This was accomplished by having ADHD children, both on and off medication, and non-ADHD children perform the task-switching paradigm, which involves the performance of two simple tasks. In nonswitch trials, an individual task is performed repeatedly for a number of trials. In switch trials, subjects must rapidly and accurately switch from one task to the other, either in a predictable or unpredictable sequence. Switch costs are calculated by subtracting performance on the nonswitch trials from performance on the switch trials. These costs are assumed to reflect the executive control processes required for the coordination of multiple tasks. ADHD children showed substantially larger switch costs than non-ADHD children. However, when on medication, the ADHD children's switch performance was equivalent to control children. In addition, medication was observed to improve the ADHD children's ability to inhibit inappropriate responses. These data are discussed in terms of models of ADHD and cognition.     

Establishing a Link Between Attention Deficit Disorder/Attention Deficit Hyperactivity Disorder and Childhood Physical Abuse

Attention deficit disorder and attention deficit/hyperactivity disorders (ADD/ADHD) are found in approximately 5% to 10% of school-aged children. This study examined whether childhood physical abuse was associated with ADD/ADHD. Data were derived from a population-based sample of 13,054 adults from the 2005 Canadian Community Health Survey. We used logistical regression analysis in 2 models, both of which had ADD/ADHD as the criterion variable. There were 7 times higher odds of ADD/ADHD among those who reported they had been abused after controlling for several potential mediating factors, including age, race, gender, and 3 other types of adverse childhood experiences (parental divorce, parental addictions, and long-term parental unemployment) in comparison to those who were not abused. The results of this analysis show a strong link between childhood abuse and ADD/ADHD, an association that requires further study.     

A Meta-Analysis of the Association Between Birth Weight and Attention Deficit Hyperactivity Disorder

A large body of work has investigated the association between birth weight and ADHD and has resulted in mixed findings with regard to the direction and magnitude of this association. Despite the vast amount of research on this topic, a comprehensive and systematic quantification of the association between birth weight and ADHD has yet to be undertaken. A meta-analysis of 88 unique studies (N?=?4,645,482) was conducted to quantify the overall effect size of birth weight on ADHD symptoms. Several variables were examined as moderators that may contribute to systematic variation in effect sizes. Overall, birth weight was found to have a small, but significant, association with ADHD symptoms such that individuals born at lower birth weights manifested greater symptoms of ADHD (r?=??0.15). Sample type, mean birth weight of the sample, geographic region, the informant of ADHD symptoms, ADHD symptom measurement method, and race were all found to contribute significantly to heterogeneity in effect sizes. Notably, several early life risk factors previously found to be associated with both ADHD and birth weight, gestational age and prenatal smoking exposure, were not found to contribute to heterogeneity in effect sizes. The findings of the current analyses align with the growing recognition that early life adversity contributes to neurodevelopmental difficulties, and the findings highlight the importance of a better understanding of the mechanisms underlying the association between early life risk factors and adverse neurodevelopmental sequela, such as that observed in ADHD.     

The Development of Selective Attention in Children With Attention Deficit Hyperactivity Disorder

The influence of age on a selective attention task was studied in a sample of children with and without Attention Deficit Hyperactivity Disorder (ADHD). The impact of methylphenidate (MPH) treatment on selective attention was also investigated in the children with ADHD. Two age groups of children with ADHD and two age groups of control children were tested using a timed computer task. The task consisted of identifying visual target stimuli under various distracter conditions. Distracters varied on the basis of modality (i.e., visual, auditory, or both) and task relevance (i.e., meaningful or irrelevant). Reaction times and accuracy were measured. Children with ADHD were less efficient on the selective attention task than were children without ADHD, and older children were more efficient than younger children in both groups. Children without ADHD were influenced more by the nature of distracters than were children with ADHD. For children with ADHD, MPH improved performance overall.     

注意缺陷多动障碍儿童的表征搜索

为探索ADHD儿童在时间维度上的视觉选择性注意的基本机制,揭示其表征搜索能力是否存在缺陷,研究采用RSVP范式,通过实验材料(字母和数字)和呈现方式操作两种搜索方式:序列搜索和平行搜索,比较ADHD儿童(18名)和控制组儿童(17名)的成绩差异。结果发现:①在平行搜索和序列搜索条件下,ADHD儿童的成绩均低于正常控制组;②比较平行搜索和序列搜索条件下的成绩变化,以及由低难度到高难度上成绩的变化,无论是正确率还是反应时均发现ADHD儿童和正常儿童具有相同的成绩变化模式。结论认为ADHD儿童在视觉选择性注意的基本搜索机制上并不存在明显缺陷。     

Nature, Nurture, and Attention Deficit Hyperactivity Disorder

This commentary shows that Joseph's (this issue) review of the genetics of attention deficit hyperactivity disorder (ADHD) contains errors of scientific logic and ignores much relevant research. Thus, we reject his conclusions. We also reject Joseph's approach of pitting nature against nurture as if these two facets of human life are at odds with one another. Instead, most scientists who study the genetics of psychiatric disorders embrace the idea that these disorders are influenced by both genes and environmental factors. In fact, the twin studies criticized by Joseph provide the strongest evidence that environmental risk factors play a substantial role in the etiology of ADHD. They do so by showing that when one identical twin has ADHD the risk to the co-twin is much less than 100%, a fact which can only be explained by environmental risk factors. We also reject the idea that genetic studies have hindered psychosocial research, stigmatized patients, or promoted psychopharmacologic treatments. Genetic studies have aimed at solving one part of the puzzle of ADHD. By testing a parsimonious theory, they have set the stage for gene discovery and the delineation of how genes and environment combine to cause this impairing disorder.     

Evidence for an Error Monitoring Deficit in Attention Deficit Hyperactivity Disorder

We studied error monitoring in ADHD and control children in a task requiring inhibition of a motor response. The extent of slowing following successful (stopped) and failed (nonstopped) inhibition was compared across groups. We also measured the time required to inhibit a response (stop signal reaction time, SSRT). Compared to controls, ADHD participants slowed less following nonstopped responses. Slowing did not vary with comorbid reading, oppositional, conduct or anxiety disorder, sex or ADHD subtype. Slowing after nonstopped responses was marginally, although significantly correlated with total ADHD symptoms and with age. ADHD participants had significantly longer SSRT than controls, but SSRT was not significantly correlated with slowing. The apparent deficit in error monitoring in ADHD and its independence from the inhibition deficit observed in ADHD has implications for executive control models of ADHD, performance problems associated with the disorder and for component theories of executive control.     

Diagnosis and Treatment of Adults With Attention Deficit Hyperactivity Disorder

It is estimated that between 30% and 50% of children diagnosed with attention deficit hyperactivity disorder (ADHD) will continue to exhibit symptomatology that is disruptive throughout their adult lives. Identification and diagnosis of adult ADHD, as well as primary and secondary characteristics and comorbid disorders, are discussed in this article. Counseling strategies are suggested to help clinicians treat adults with ADHD, such as educating the client about the disorder and providing training in attention management techniques, self-management skills, interpersonal and social skills, stress and time management, anger management, and problem-solving skills. Clinicians are encouraged to prepare themselves for understanding, identifying, diagnosing, and treating the adult population with ADHD.     

Processing Speed in Children With Attention Deficit/Hyperactivity Disorder,Inattentive Type

Attention Deficit/Hyperactivity Disorder (ADHD) is among the most common and most often reconceptualized neurobehavioral disorders of childhood. In the most recent DSM-IV, a primarily inattentive subtype of ADHD (AD) has again been identified. This study explores the neuropsychological profile of this group of children. Eighty-two children referred for school-related problems participated. Twenty-five met criteria for AD; 52 met criteria for reading disability (RD); 9 were comorbid for RD and AD. AD children performed poorly on measures of information processing speed. Children with comorbid AD/RD were distinguishable from those with RD on speed of processing measures only. Vulnerability to information processing load may be at the root of many of the behavioral manifestations of AD.     

Psychological therapy for adults with Attention Deficit Hyperactivity Disorder

In the liteature, the clinical management of adults with Attention Deficit Hyperactivity Disorder has focused almost exclusively on stimulant medication. Yet psychological therapy may be a useful adjunct to stimulant medication. Pharmacotherapy is generally reported to be efficacious and, as such, treated individuals are likely to be more receptive to psychological intervention. The aim of this paper is to consider how an individual may best be supported by psychological therapy. It is recommended that a structured pragmatic, psychoeducative approach is the most appropriate. The development of specific self-management skills is discussed within a cognitive behavioural framework. Family, marital and group therapies are also discussed.     

Very Low Birth Weight and Attention Deficit/Hyperactivity Disorder

It is well recognized that reaction time performance of term-born children with a normal birth weight (NBW > 2500 g) who fulfill the DSM-IV criteria for attention deficit/hyperactivity disorder (ADHD) in the primary school age is sensitive for the presentation rate of stimuli. They have been found to perform more poorly in conditions of relatively slow event rates as compared with fast event rates. The purpose of the current study was to explore whether reaction time performance of children with very low birth weight (VLBW < 1500 g) with or without ADHD showed the same sensitivity for the factor presentation rate of stimuli compared to children with a normal birth weight plus ADHD. To this end, reaction time performance of four groups of children was compared on a Go/No-Go test with a fast presentation rate of 1 second and a slow presentation rate of 6 seconds. Groups were: children with VLBW plus ADHD, children with VLBW only, children born full term with normal birth weight (NBW >2500 g) plus ADHD, and children born full term without ADHD (the control group). Findings indicated that, compared to the non-ADHD groups, the groups with ADHD (NBW and VLBW) showed a more dramatic decline in their reaction time performance in the slow condition: a state regulation deficit. In addition, both groups showed a response inhibition deficit. No difference was found in reaction time performance between the groups of children with VLBW only and the control group.     

Automatic and effortful processing in Attention Deficit/Hyperactivity Disorder

Twenty-five boys with Attention Deficit/Hyperactivity Disorder and 23 age-matched controls were compared on verbal memory tasks differentiating automatic versus effortful information processing. Automatic processing tasks included the recognition of new or old words in a list and the recognition of frequency of occurrence of words in a list. Effortful tasks included free recall of lists of both related and unrelated words. Hyperactive boys did not differ from controls in automatic processing capabilities but demonstrated significantly poorer effortful processing. Intercorrelations of the variables revealed high correlations between scores on effortful measures and also raise questions about the purity of automaticity in some tasks employed. Stepwise discriminant analysis demonstrated that free recall of related words (an effortful task) best discriminated between groups. Effort-related processing in hyperactive and normal children is discussed in relation to variables of motivation, affect, arousal, and other higher-order cognitive processes.     

Psychosocial Treatments for Children with Attention Deficit/Hyperactivity Disorder

This article reviews studies examining the efficacy of behavioral interventions for the treatment of attention-deficit/hyperactivity disorder (ADHD). A specific emphasis is placed on evidence-based interventions that include parent training, classroom, academic, and peer interventions. Results indicate that school-aged children respond to behavioral interventions when they are appropriately implemented both at home and in the classroom setting. Combined treatments (behavioral management and stimulant medication) represent the gold standard in ADHD treatment and are often recommended as the first-line treatment option due to the many problems faced by children with ADHD. Diversity issues, although an important consideration in the treatment of ADHD, continue to remain an understudied area. Recommendations for future research are made pertaining to treatment sequencing with regard to behavior management as well as for subgroups of ADHD children who may respond best to specific treatments.     

ADHD儿童与正常儿童在视觉—动作方面的比较研究

10岁到13岁男性ADHD儿童在镶嵌图形、眼手协调、视力追踪和数字划销等视觉—动作实验上的分数显著低于同一年龄段的男性正常儿童,显示ADHD儿童的视觉—动作能力比正常儿童差.ADHD儿童与正常儿童相比,知觉方式的场独立性较弱,心理机能分化程度较低.ADHD儿童在长度估计实验上没有发现异常.     

Interference Control in Children with Attention Deficit/Hyperactivity Disorder

The view that Attention Deficit/Hyperactivity Disorder (ADHD) is associated with a diminished ability to control interfference is controversial and based exclusively on results of (verbal)-visual interference tasks, primarily the Stroop Color Word task. The present study compares medication-naïve children with ADHD (n?=?35 and n?=?51 in Experiments 1 and 2, respectively) with normal controls (n?=?26 and n?=?32, respectively) on two interference tasks to assess interference control in both the auditory and the visual modality: an Auditory Stroop task and a Simon task. Both groups showed reliable but equal degrees of interference on both tasks, suggesting that children with ADHD do not differ from normal controls in their ability to control interference in either modality.     

Attention Deficit/Hyperactivity Disorder in Adults with Sleep Apnea

AAttention deficit hyperactivity disorder (ADHD) is a common childhood illness. In some patients, this illness may persist into adulthood and an association between ADHD and Obstructive Sleep Apnea (OSA) has been found in childhood. However, it is unclear how OSA and ADHD coincide in adulthood. Therefore, to explore the relationship between OSA and adult ADHD the current investigation utilized a clinically-based cross-sectional survey. Subjects consisted of 81 treatment-naïve OSA patients and 32 controls. Measures included each patient completed a questionnaire regarding sleep, Adult ADHD scale. Clinical information, body mass index, 36-item Short Form Health Survey (SF-36), Epworth Sleepiness Scale (ESS), Hospital Anxiety and Depression Scale, and polysomnography.The subjects with Apnea-Hypopnea Index (AHI) ≥ 5 events/h were defined as patients with OSA. The control group was accepted as individuals with AHI > 0 events/h. The prevalence of adult ADHD was not different between the patients with OSA and the control group [(7.4 % (6/75) vs. 6.3 % (2/30), p = 0.8, respectively]. OSA patients with ADHD, as compared with those without, had higher anxiety scores and poorer physical component scores of quality of life and higher ESS scores. ADHD scores in patients with OSA were associated with anxiety and depression scores and SF36 physical and mental component scores in bivariate analyses. Thus, in our sample ADHD was not a frequent illness in adult patients with OSA. However, in patients with OSA and ADHD higher levels of anxiety and daytime sleepiness and poorer quality of life was found.     

Psychological functioning in siblings of children with Attention Deficit Hyperactivity Disorder

We examined psychological functioning in siblings of children with Attention Deficit Hyperactivity Disorder (ADHD). Siblings of children diagnosed with ADHD (n = 45) between the ages of 9 and 13 and a control group (n = 46) within the same age range composed of siblings of children with no diagnosed disorders completed measures of psychological functioning. A significant multivariate difference was observed on these measures across groups. Post hoc investigation of the univariate means revealed one significant group difference, which occurred on a measure of Trait Anger. This finding suggests that future research on family members of children with ADHD may be warranted.