注意缺陷多动障碍的神经机制及干预

注意缺陷多动障碍是一种常见的神经性、发展性障碍。大脑异常被认为是注意缺陷多动障碍的病因之一。随着脑成像技术的发展,当前对该障碍的脑解剖结构病变、脑神经发育迟缓和脑网络连接异常等方面都展开了深入研究。文章从以上三个方面介绍最新研究成果,并指出目前的不足和未来研究方向,在此基础上为提高诊断精确性和发展新型有效的治疗干预方法提供建议。     

Etiologic Subtypes of Attention-Deficit/Hyperactivity Disorder: Brain Imaging, Molecular Genetic and Environmental Factors and the Dopamine Hypothesis

Multiple theories of Attention-Deficit/Hyper- activity Disorder (ADHD) have been proposed, but one that has stood the test of time is the dopamine deficit theory. We review the narrow literature from recent brain imaging and molecular genetic studies that has improved our understanding of the role of dopamine in manifestation of symptoms of ADHD, performance deficits on neuropsychological tasks, and response to stimulant medication that constitutes the most common treatment of this disorder. First, we consider evidence of the presence of dopamine deficits based on the recent literature that (1) confirms abnormalities in dopamine-modulated frontal-striatal circuits, reflected by size (smaller-than-average components) and function (hypoactivation); (2) clarifies the agonist effects of stimulant medication on dopaminergic mechanisms at the synaptic and circuit level of analysis; and (3) challenges the most-widely accepted ADHD-related neural abnormality in the dopamine system (higher-than-normal dopamine transporter [DAT] density). Second, we discuss possible genetic etiologies of dopamine deficits based on recent molecular genetic literature, including (1) multiple replications that confirm the association of ADHD with candidate genes related to the dopamine receptor D4 (DRD4) and the DAT; (2) replication of differences in performance of neuropsychological tasks as a function of the DRD4 genotype; and (3) multiple genome-wide linkage scans that demonstrate the limitations of this method when applied to complex disorders but implicate additional genes that may contribute to the genetic basis of ADHD. Third, we review possible environmental etiologies of dopamine deficits based on recent studies of (1) toxic substances that may affect the dopamine system in early development and contribute substantially to the etiology of ADHD; (2) fetal adaptations in dopamine systems in response to stress that may alter early development with lasting effects, as proposed by the developmental origins of health and disease hypothesis; and (3) gene-environment interactions that may moderate selective damage or adaptation of dopamine neurons. Based on these reviews, we identify critical issues about etiologic subtypes of ADHD that may involve dopamine, discuss methods that could be used to address these issues, and review old and new theories that may direct research in this area in the future.     

Treatment effectiveness of combined medication/behavioural treatment with chinese ADHD children in routine practice

BACKGROUND: The effectiveness of a combined methylphenidate/behavioural treatment (BT) versus methylphenidate-only for Chinese children with Attention-Deficit/Hyperactivity Disorder (ADHD) was tested in routine clinical practice in Hong Kong. METHODS: A randomized group comparison design was adopted with two treatment conditions (methylphenidate-only; methylphenidate/BT), which lasted for 6 months. There were four assessment time points (pre-treatment, post-treatment, and 6-month and 12-month follow-ups), using the Strengths and Weaknesses of ADHD Symptoms and Normal Behaviours (SWAN) Rating Scale. Parental attitude toward different treatment options of ADHD was also assessed at pre-treatment and post-treatment. Participants included 90 Chinese ADHD children (mean age=8 years, SD=.95). RESULTS: The combination of BT and a low-dose methylphenidate was significantly more effective than methylphenidate-only in reducing ADHD and ODD symptoms at post-treatment. At follow-ups, the benefits of the combined treatment were maintained, while the methylphenidate-only group caught up in improvement in ADHD symptoms. Parents in both treatment conditions showed improved attitude toward medication after the 6-month treatment phase, while their attitude toward BT was positive all along. CONCLUSIONS: This study supported the added benefits of BT, on top of medication, for Chinese ADHD children in routine practice with treatments conducted by regular medical and paramedical staffs.     

Clinical and functional correlates of processing speed in pediatric Attention-Deficit/Hyperactivity Disorder: a systematic review and meta-analysis

It is well established that processing speed is negatively impacted in children and adolescents with Attention-Deficit/Hyperactivity Disorder (ADHD). Unfortunately, exactly how processing speed vulnerabilities manifest in daily functioning has not been well established. To support clinical care of youth with ADHD, it is important to better understand the functional consequences and relevant outcomes associated with processing speed deficits. This systematic review and meta-analysis sought to identify the association between processing speed and clinical or functional correlates among children or adolescents diagnosed with ADHD. A total of 409 abstracts were screened, of which, 60 full-text articles were identified as potentially relevant, and 8 of these studies met inclusion criteria. Domains evaluated across these studies included reading skills, mathematics skills, written expression, anxiety, self-appraisals of competence, and adaptive functioning. Six studies reported an association between processing speed and reading skills, allowing for meta-analysis. Processing speed difficulties among youth with ADHD appear strongly associated with several clinical and functional correlates including weaker academic skills, poorer adaptive skills, increased self-reported anxiety, and overestimates of social competence. Meta-analytic results for studies reporting the association between processing speed and reading skills indicate a medium overall weighted mean effect size (r = 0.33, 95% CI = 0.28 –0.39) with minimal heterogeneity (I² = 0.17). Clinical implications of these findings, limitations in the current knowledge base, and suggestions for future research are discussed.     

Teachers' Ratings of Attention-Deficit Hyperactivity Disorder and Decisions for Referral for Services in Taiwan

We examined the relationship between elementary teachers' perceptions and ratings of Attention-Deficit Hyperactivity Disorder (ADHD) symptoms of students and their referral decisions in public schools in Taiwan. One hundred and twenty-one homeroom teachers were randomly selected from six public elementary schools in Taipei County, Taiwan, to participate in the study. The study contained two groups of children, a random sample (n — 478) and a nominated sample (n = 219). Results of the discriminant analyses showed that Chinese teachers' ratings of ADHD could predict group membership as to whether a student had been or might be referred. This study found that, despite the fact that Chinese teachers believed children with scores two standard deviations above the mean had behavior problems, teachers decided not to refer those students. Teachers were more likely to refer children whose scores were three standard deviations above the mean.     

WISC-III Cognitive Profiles in Children with ADHD: Specific Cognitive Impairments and Diagnostic Utility

This study aimed to investigate the presence of specific cognitive impairments and the diagnostic utility of the WISC-III in children with ADHD. Ninety-eight children with ADHD and 81 children without ADHD matched by age and gender (control group), between the ages of 6 and 12?years, participated in the study. Children with ADHD revealed the most pronounced deficits in the subtests tapping working memory and processing speed. Freedom from Distractibility was the cognitive profile most impaired and that showed the highest diagnostic accuracy to discriminate children with ADHD. The optimal cutoff scores of the most common WISC-III cognitive profiles revealed greater diagnostic accuracy than the traditional approach of full or partial profiles. Taken together, these results suggested that in the context of a comprehensive psychological assessment, the WISC may provide knowledge about the specific cognitive strengths and weaknesses that characterize this disorder and may be useful in the decision-making process relative to ADHD diagnosis.     

Exploratory Eye Movements to Pictures in Childhood-Onset Schizophrenia and Attention-Deficit/Hyperactivity Disorder (ADHD)

We investigated exploratory eye movements to thematic pictures in schizophrenic, attention-deficit/hyperactivity disorder (ADHD), and normal children. For each picture, children were asked three questions varying in amount of structure. We tested if schizophrenic children would stare or scan extensively and if their scan patterns were differentially affected by the question. Time spent viewing relevant and irrelevant regions, fixation duration (an estimate of processing rate), and distance between fixations (an estimate of breadth of attention) were measured. ADHD children showed a trend toward shorter fixations than normals on the question requiring the most detailed analysis. Schizophrenic children looked at fewer relevant, but not more irrelevant, regions than normals. They showed a tendency to stare more when asked to decide what was happening but not when asked to attend to specific regions. Thus, lower levels of visual attention (e.g., basic control of eye movements) were intact in schizophrenic children. In contrast, they had difficulty with top-down control of selective attention in the service of self-guided behavior.     

Parenting stress in parents of children with attention-deficit hyperactivity disorder and parents of children with learning disabilities

Parenting a child with ADHD can challenge parenting resources and coping. Increasingly, researchers are examining the relationship between the behavior of the child with ADHD and family functioning. While studies have shown inceased parenting stress in parents of children with ADHD, these studies have compared children with ADHD to non-disabled children. This study compares reports of parenting stress among mothers of children with ADHD, mothers of children with learning disabilities and mothers of non-referred children. Results showed that parenting stress was highest for mothers of children with ADHD. Increased parenting stress was associated with child characteristics and, in particular, with externalizing behavior problems.     

Performance and Private Speech of Children with Attention-Deficit/Hyperactivity Disorder While Taking the Tower of Hanoi Test: Effects of Depth of Search,Diagnostic Subtype,and Methylphenidate

We administered the Tower of Hanoi to demographically comparable samples of control participants (n = 34) and children with the Combined (n = 22) and Inattentive subtypes (n = 19) of Attention-Deficit/Hyperactivity Disorder (ADHD). Controls excelled over children with the Inattentive subtype, who outperformed patients with the Combined subtype. These results replicated findings of greater executive deficits in the Combined than in the Inattentive type of ADHD. Double-blind administration of methylphenidate improved task performance only for patients with the Inattentive subtype. In a drug-free Baseline session, children with both subtypes of ADHD made more private verbalizations than controls, particularly when failing puzzles. In later sessions, regardless of drug condition, the inattentive sample exhibited a smaller increase in self-regulatory utterances under failure. In contrast, the combined sample decreased self-regulatory verbalizations under failure only under methylphenidate. The results support some differences between the two subtypes of ADHD in executive functioning and in their response to stimulant therapy. Portions of these results were submitted as part of H. Theresa Chang's PhD dissertation (Chang, 2000) and Helena Kopecky's unpublished master's research, both conducted at the University of Rochester and supervised by Rafael Klorman.     

The Importance of Parental Attributions in Families of Children with Attention-Deficit/Hyperactivity and Disruptive Behavior Disorders

Presents a social-cognitive model outlining the role of parental attributions for child behavior in parent–child interactions. Examples of studies providing evidence for the basic model are presented, with particular reference to applications of the model in families of children with Attention-Deficit/Hyperactivity Disorder (ADHD) and/or oppositional defiant/conduct disordered behavior. Parent or child factors that may moderate the operation of links within the model are suggested, and evidence of such moderator effects is presented. The conceptualization and measurement of parental attributions also are discussed. The limitations of the model and existing evidence, as well as recommendations for future research in this area are presented throughout the paper. The paper concludes with a summary of the clinical implications of the model and research on parental attributions with regards to improving interventions for families of children with attentional and disruptive behavior problems.     

Occupational Therapy Interventions for Children with Attention Deficit Hyperactivity Disorder: A Systematic Review

This systematic review examined evidence published 2005–2015 for occupational therapy interventions for children with Attention Deficit Hyperactivity Disorder (ADHD). We identified 590 abstracts with 17 full-text articles eligible for review. Fourteen articles were included in the final analysis with two level I studies, two level II studies, eight level III studies, and two level IV studies. Occupational therapy interventions focused on play, sensory, motor, and cognitive skills. While the interventions yielded good results, there were limitations in study design, interventions, and outcome measures. Future research should include larger sample size, randomization, control groups, and interventions that can be replicated.     

Empathy and Social Perspective Taking in Children with Attention-Deficit/Hyperactivity Disorder

This study explored empathy and social perspective taking in 8 to 12 year old children with and without Attention-Deficit/Hyperactivity Disorder (ADHD). The sample comprised 92 children, 50 with a diagnosis of ADHD and 42 typically developing comparison children. Although children with ADHD were rated by their parents as less empathic than children without ADHD, this difference was accounted for by co-occurring oppositional and conduct problems among children in the ADHD sample. Children with ADHD used lower levels of social perspective taking coordination in their definition of problems, identification of feelings, and evaluation of outcomes than children without ADHD, and these differences persisted after the role of language abilities, intelligence and oppositional and conduct problems were taken into account. Girls were more empathic and had higher overall social perspective taking scores than boys. Implications for research and practice are discussed. This research was funded by the Social Sciences and Humanities Research Council (SSHRC).     

Stimulant Treatment Reduces Lapses in Attention among Children with ADHD: The Effects of Methylphenidate on Intra-Individual Response Time Distributions

Recent research has suggested that intra-individual variability in reaction time (RT) distributions of children with ADHD is characterized by a particularly large rightward skew that may reflect lapses in attention. The purpose of the study was to provide the first randomized, placebo-controlled test of the effects of the stimulant methylphenidate (MPH) on this tail and other RT distribution characteristics. Participants were 49 9- to 12-year-old children with ADHD. Children participated in a 3-day double-blind, placebo-controlled medication assessment during which they received long-acting MPH (Concerta®), with the nearest equivalents of 0.3 and 0.6 mg/kg t.i.d. immediate-release MPH. Children completed a simple two-choice speeded discrimination task on and off of medication. Mode RT and deviation from the mode were used to examine the peak and skew, respectively, of RT distributions. MPH significantly reduced the peak and skew of RT distributions. Importantly, the two medication effects were uncorrelated suggesting that MPH works to improve both the speed and variability in responding. The improvement in variability with stimulant treatment is interpreted as a reduction in lapses in attention. This, in turn, may reflect stimulant enhancement of self-regulatory processes theorized to be at the core of ADHD.     

Time Perception: Modality and Duration Effects in Attention-Deficit/Hyperactivity Disorder (ADHD)

Time perception performance was systematically investigated in adolescents with and without attention-deficit/hyperactivity disorder (ADHD). Specifically, the effects of manipulating modality (auditory and visual) and length of duration (200 and 1000 ms) were examined. Forty-six adolescents with ADHD and 44 controls were administered four duration discrimination tasks and two control tasks, and a set of standardized measures. Participants with ADHD had higher thresholds than controls on all of the duration discrimination tasks, with the largest effect size obtained on the visual 1000 ms duration discrimination task. No group differences were observed on the control tasks. Visual–spatial memory was found to be a significant predictor of visual and auditory duration discrimination at longer intervals (1000 ms) in the ADHD sample, whereas auditory verbal working memory predicted auditory discrimination at longer intervals (1000 ms) in the control sample. These group differences suggest impairments in basic timing mechanisms in ADHD.     

The Efficacy, Safety, and Practicality of Treatments for Adolescents with Attention-Deficit/Hyperactivity Disorder (ADHD)

Studies examining interventions for adolescents diagnosed with attention-deficit/hyperactivity disorder (ADHD) were reviewed to evaluate their efficacy. These efficacy findings were supplemented with a preliminary system for judging safety and practicality. Results suggest that the stimulant drug methylphenidate (MPH) is safe and well-established empirically, but has some problems with inconvenience and noncompliance. Preliminary research supports the efficacy, safety, and practicality of some psychotherapeutic interventions, including behavioral classroom interventions, note-taking training, and family therapy. Treatment with tricyclic antidepressants was judged to have minimal empirical support and debatable safety. Very little is known about long-term effectiveness of treatments, long-term compliance, or multimodal treatments for adolescents such as stimulants plus behavior therapy.     

Adrenocortical Functioning in Boys with Attention-Deficit/Hyperactivity Disorder: Examining Subtypes of ADHD and Associated Comorbid Conditions

Disruptions to hypothalamic-pituitary-adrenal (HPA) axis function have been associated with varying forms of psychopathology in children. Studies suggesting children with ADHD have blunted HPA function have been complicated by the prevalence of comorbid diagnoses and heterogeneity of ADHD. The goals of this research were to assess the relations between waking and stress–response salivary cortisol levels and comorbid disruptive behavior (DBD) and anxiety (AnxD) disorders and problems in boys with ADHD, and to examine whether cortisol levels varied across ADHD subtypes. One hundred seventy elementary school-age boys with ADHD provided salivary cortisol at waking and in reaction to venipuncture. Parent reports were used to assess boys’ psychiatric diagnoses and severity of behavioral problems. Boys’ comorbid AnxD and anxiety problems were associated with greater cortisol reactivity, whereas boys’ comorbid DBD and oppositional problems predicted diminished adrenocortical activity. Reactive cortisol increases were greatest in boys with ADHD and comorbid AnxD, but without DBD. ADHD subtypes were not differentially associated with waking, pre-stress baseline, or reactive cortisol levels. However, comorbid DBD predicted decreased cortisol reactivity in boys with inattentive and hyperactive subtypes of ADHD, but not in boys with combined subtype of ADHD. The results clarify previous patterns of distinct and divergent dysregulations of HPA function associated with boys’ varying kinds of psychopathology.

Components of Visual Search in Childhood-Onset Schizophrenia and Attention-Deficit/Hyperactivity Disorder

This study tested the hypotheses that visual search impairments in schizophrenia are due to a delay in initiation of search or a slow rate of serial search. We determined the specificity of these impairments by comparing children with schizophrenia to children with attention-deficit hyperactivity disorder (ADHD) and age-matched normal children. The hypotheses were tested within the framework of feature integration theory by administering children tasks tapping parallel and serial search. Search rate was estimated from the slope of the search functions, and duration of the initial stages of search from time to make the first saccade on each trial. As expected, manual response times were elevated in both clinical groups. Contrary to expectation, ADHD, but not schizophrenic, children were delayed in initiation of serial search. Finally, both groups showed a clear dissociation between intact parallel search rates and slowed serial search rates.     

Parent and Teacher Ratings of Attention-Deficit/Hyperactivity Disorder in Preschool: The ADHD Rating Scale-IV Preschool Version

Efforts for early identification and intervention for children with AD/HD have necessitated the development of rating scales of behavior for the preschool population. The standardization, reliability, and validity data were presented for the ADHD Rating Scale-IV Preschool Version. Parent and teacher ratings were collected on 902 and 977 children 3 to 5 years of age, respectively. Raw scores for the Inattention, Hyperactivity/Impulsivity and Total scores were converted to T-Scores and percentile ranks. Reliability coefficients ranged from 0.80 to 0.95 indicating good test–retest reliability. Concurrent validity with the Conners Teacher Rating Scales: Revised-Short and Conners Parent Rating Scale: Revised-Short ranged from 0.54 to 0.96. The ADHD-Rating Scale-IV appears to be a reliable, valid and user friendly measure for screening preschoolers with behavior problems. Future research is needed to validate its widespread use as a screening and diagnostic tool.     

Decision Making with Uncertain Reinforcement in Children with Attention Deficit/Hyperactivity Disorder (ADHD)

Reward-related processes are impaired in children with ADHD. Whether these deficits can be ascribed to an aversion to delay or to an altered responsiveness to magnitude, frequency, valence, or the probability of rewards still needs to be explored. In the present study, children with ADHD and normal controls aged 7 to 10 years performed a simple probabilistic discounting task. They had to choose between alternatives where the magnitude of rewards was inversely related to the probability of outcomes. As a result, children with ADHD opted more frequently for less likely but larger rewards than normal controls. Shifts of the response category after positive or negative feedback, however, occurred as often in children with ADHD as in control children. In children with ADHD, the frequency of risky choices was correlated with neuropsychological measures of response time variability but unrelated to measures of inhibitory control. It is concluded that the tendency to select less likely but larger rewards possibly represents a separate facet of dysfunctional reward processing, independent of delay aversion or altered responsiveness to feedback.