Predicting the Early Developmental Course of Symptoms of Attention Deficit Hyperactivity Disorder

Data from the National Institute of Child Health and Human Development Study of Early Child Care were examined to test whether: attention deficit/hyperactivity disorder (ADHD) symptoms remain stable from 54 months through early elementary school; behavioral inhibition and attention deficits assessed at 54 months predict ADHD symptoms in elementary school, even after controlling for their temporal stability; and early behavioral inhibition and attention deficits moderate the longitudinal stability in ADHD symptoms. Data were examined using continuous and categorical measures of symptoms. Modest stability in ADHD symptoms from 54 months to third grade was found. Measures of inhibition and inattention predicted later teacher ratings uniquely, but no evidence was found for moderation. Measures of preschool behavioral inhibition also predicted “persistently at risk status” defined by elevated teacher ratings over time. Results are discussed in terms of executive and motivational facets of inhibition that may be related to early signs of ADHD.     

Arousal,Suppression, and Persistence: Frustration Theory,Attention, and its Disorders

Abstract

In this article I deal first with the relevance of theories of frustration and general persistence to the concept of attention, and offer an interpretation of attention deficit hyperactivity disorder (ADHD) in terms of persistence deficits. After summarising these theories and the manner in which they integrate the concepts of arousal, suppression, and persistence, I describe relevant developmental work in infant rats comprising an ontogenetic sequence of first appearance of a number of reward-schedule effects, and suggest their possible utility as a behavioural assay. Finally, I briefly review neuroanatomical and behavioural work on fetal alcohol and its possible implications for theories of attention and hyperactivity, and provide some data from experiments on fetal alcohol effects in infant rats which may have some relevance to such an interpretation.     

Differences in feedback- and inhibition-related neural activity in adult ADHD

The objective of this study was to examine response inhibition- and feedback-related neural activity in adults with attention deficit hyperactivity disorder (ADHD) using event-related functional MRI. Sixteen male adults with ADHD and 13 healthy/normal controls participated in this study and performed a modified Go/NoGo task. Behaviourally, attention and inhibition problems in the ADHD group were observed; no feedback-related differences between the groups were detected. The neuroimaging data showed that the ADHD group displayed more activation in the inferior frontal gyrus and putamen during response inhibition. During feedback-related processes, the ADHD group displayed less activation in the inferior frontal/orbitofrontal cortex, hippocampus/nucleus accumbens, and caudate nucleus, but more activity in the inferior frontal gyrus. These results indicate that at least two distinguishable underlying brain networks related to response inhibition and feedback are altered in adults with ADHD.     

Is ADHD a disinhibitory disorder?

Attention deficit hyperactivity disorder (ADHD) is widely theorized to stem from dysfunctional inhibitory processes. However, the definition of inhibition is imprecisely distinguished across theories. To clarify the evidence for this conception, the author relies on a heuristic distinction between inhibition that is under executive control and inhibition that is under motivational control (anxiety or fear). It is argued that ADHD is unlikely to be due to a motivational inhibitory control deficit, although suggestions are made for additional studies that could overturn that conclusion. Evidence for a deficit in an executive motor inhibition process for the ADHD combined type is more compelling but is not equally strong for all forms of executive inhibitory control. Remaining issues include specificity to ADHD, whether inhibitory problems are primary or secondary in causing ADHD, role of comorbid anxiety and conduct disorder, and functional deficits in the inattentive ADHD subtype.     

奖惩对注意缺陷多动障碍儿童情感决策的影响

采用简化版儿童赌博任务,其中操纵了奖励和惩罚的强度,探察两种亚型（注意缺陷型和混合型）ADHD儿童的情感决策能力,同时采集儿童在任务中的皮肤电活动以探析ADHD儿童在情感决策中的生理机制。结果发现,在不同的奖惩强度下,ADHD儿童情感决策模式不同,在即刻奖励条件下,ADHD儿童情感决策的能力明显弱于正常对照组儿童,倾向于不利选择,所产生的预测性皮电振幅也明显低于正常对照组;在即刻惩罚条件下,ADHD儿童的情感决策能力未见异常。两种亚型ADHD儿童的表现模式相似。上述结果证明,ADHD儿童仅存在对奖励的异常敏感性,并确实影响了其决策能力,而其回避惩罚的能力正常。两种亚型ADHD儿童存在的问题相似     

Attentional networks,vigilance, and distraction as a function of attention-deficit/hyperactivity disorder symptoms in an adult community sample

Attentional difficulties are a core axis in attention-deficit/hyperactivity disorder (ADHD). However, establishing a consistent and detailed pattern of these neurocognitive alterations has not been an easy endeavour. Based on a dimensional approach to ADHD, the present study aims at comprehensively characterizing three key attentional domains: the three attentional networks (alerting, orienting, and executive attention), two components of vigilance (executive and arousal vigilance), and distraction. To do so, we modified a single, fine-grained task (the ANTI-Vea) by adding irrelevant distractors. One hundred and twenty undergraduates completed three self-reports of ADHD symptoms in childhood and adulthood and performed the ANTI-Vea. Despite the low reliability of some ANTI-Vea indexes, the task worked successfully. While ADHD symptoms in childhood were related to alerting network and arousal vigilance, symptoms in adulthood were linked to executive vigilance. No association between ADHD symptom severity and executive attention and distraction was found. In general, our hypotheses about the relationships between ADHD symptoms and attentional processes were partially supported. We discuss our findings according to ADHD theories and attention measurement.     

Attention-Deficit/Hyperactivity Disorder and Behavioral Inhibition: A Meta-Analytic Review of the Stop-signal Paradigm

Deficient behavioral inhibition (BI) processes are considered a core feature of attention deficit/hyperactivity disorder (ADHD). This meta-analytic review is the first to examine the potential influence of a wide range of subject and task variable moderator effects on BI processes--assessed by the stop-signal paradigm--in children with ADHD relative to typically developing children. Results revealed significantly slower mean reaction time (MRT), greater reaction time variability (SDRT), and slower stop-signal reaction time (SSRT) in children with ADHD relative to controls. The non-significant between-group stop-signal delay (SSD) metric, however, suggests that stop-signal reaction time differences reflect a more generalized deficit in attention/cognitive processing rather than behavioral inhibition. Several subject and task variables served as significant moderators for children's mean reaction time.     

成人注意缺陷多动障碍诊断与心理治疗的研究进展

注意缺陷多动障碍（ADHD）是指一种以注意缺陷、多动、冲动的行为表现为主要特征的精神病理障碍。对儿童注意缺陷多动障碍的研究有了长足的进步,但对成人注意缺陷多动障碍的研究相对较少。本文阐明了国际上对成人注意缺陷多动障碍的诊断与心理治疗的研究进展,希望引起国内临床心理学家、精神病学家和心理咨询师等的充分重视。     

Developmental change in the relation between executive functions and symptoms of ADHD and co‐occurring behaviour problems

In a sample of 92 children aged 6–13 years this study investigates the normal developmental change in the relation between executive functioning (EF) and the core behavioural symptoms associated with attention deficit hyperactivity disorder (ADHD) (hyperactivity/impulsivity and inattention) as well as symptoms often co‐occurring with childhood hyperactivity (conduct‐ and internalizing problems). EF was assessed by using multiple tests grouped through prior factor analysis, resulting in cognitive measures relating to disinhibition, speed/arousal, verbal working memory, non‐verbal working memory, and fluency. The results showed that although disinhibition was positively related to hyperactivity/impulsivity and inattention mainly for the youngest age group, there were no significant age effects for these relations. Instead, age effects were found for the relations between speed/arousal and inattention as well as for the relations between verbal working memory/fluency and inattention. In the oldest age group poor performance on these cognitive measures was associated with high ratings of inattention. For the total sample a relation was obtained between disinhibition and hyperactivity/impulsivity as well as between both working memory measures and internalizing problems. In conclusion, the results from this study suggest that poor inhibition is most clearly associated with ADHD symptoms for younger children, whereas poor functioning with regard to later developing and more complex executive functions such as working memory and fluency is associated with ADHD symptoms for older children. Copyright © 2006 John Wiley & Sons, Ltd.     

Stimulus-dependent dopamine release in attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is related to an attenuated and dysfunctional dopamine system. Normally, a high extracellular dopamine level yields a tonic dopaminergic input that down-regulates stimuli-evoked phasic dopamine responses through autoreceptors. Abnormally low tonic extracellular dopamine in ADHD up-regulates the autoreceptors so that stimuli-evoked phasic dopamine is boosted. The authors propose that these boosted phasic responses yield hypersensitivity to environmental stimuli in ADHD. Stimuli evoking moderate brain arousal lead to well-functioning performance, whereas either too little or too much stimuli attenuate cognitive performance. Strong, salient stimuli may easily disrupt attention, whereas an environment with impoverished stimuli causes low arousal, which is typically compensated for by hyperactivity. Stochastic resonance is the phenomenon that makes a moderate noise facilitate stimulus discrimination and cognitive performance. Computational modeling shows that more noise is required for stochastic resonance to occur in dopamine-deprived neural systems in ADHD. This prediction is supported by empirical data.     

Working memory and behavioral inhibition in boys with ADHD: An experimental examination of competing models

Working memory (WM) and behavioral inhibition impairments have garnered significant attention as candidate core features, endophenotypes, and/or associated neurocognitive deficits of attention-deficit/hyperactivity disorder (ADHD). The relationship between ADHD-related WM and inhibition deficits remains relatively unclear, however, with inferences about the constructs’ directional relationship stemming predominantly from correlational research. The current study utilized a dual-task paradigm to experimentally examine the relationship between ADHD-related WM and behavioral inhibition deficits. A total of 31 boys (15 ADHD and 16 typically developing [TD]) aged 8–12 years completed WM (1-back and 2-back), behavioral inhibition (stop-signal task [SST]), and dual-condition (1-back/SST and 2-back/SST) experimental tasks. Children with ADHD exhibited significant, large-magnitude WM deficits for the 1-back condition but were not significantly different from children in the TD group for the 2-back, 1-back/SST, and 2-back/SST conditions. Children with ADHD also exhibited significant inhibition deficits for the SST, 1-back/SST, and 2-back/SST conditions, but the within-group effect was not significant. The findings suggest that ADHD-related stop-signal demands are upstream, or compete for, resources involved in controlled-focused attention and/or other central executive (CE), WM processes.     

A review of adult ADHD: a neuropsychological and neuroimaging perspective

Attention-deficit/hyperactivity disorder (ADHD) is a developmental disorder which effects an estimated 3% to 5% of children. Despite estimates that ADHD persists in 30% to 70% of adults having had the disorder in childhood, ADHD in adulthood remains controversial. This report summarizes current thinking in the diagnosis and etiology of adult ADHD. Most theories posit that ADHD is related to anomalies in frontal lobe function and dopaminergic transmission. However, there is debate as to whether ADHD is a unitary disorder with different manifestations, a syndrome, or multiple disorders. The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, classifies ADHD into inattention, hyperactivity-impulsivity, and combined subtypes. Although problems with cognition are core ADHD symptoms, self-reporting has not been a reliable predictor of neuropsychological test performance. Nevertheless, we suggest that a performance-based diagnosis, including empirically derived, age-sensitive neuropsychological tests, provides the best hope of dissociating ADHD from psychiatric disorders with similar symptoms. We also describe the promise of new neuroimaging technologies, such as functional magnetic resonance imaging, in elucidating the pathophysiology of ADHD and similar psychiatric disorders.     

Assessment of executive function in ADHD adolescents: contribution of performance tests and rating scales

This study aimed to analyze performance on measures of neuropsychological and behavioral executive functions (EF) in adolescents with attention deficit hyperactivity disorder (ADHD), and to evaluate the utility of performance-based tests for predicting scores on behavioral EF ratings. One hundred eighteen adolescents (75 ADHD and 43 controls) aged 12–16 years performed neuropsychological tests and completed a behavior rating scale of EF. The ADHD group presented significantly lower scores than controls on Full Scale IQ (FSIQ) and all indexes of the WISC-IV, except the verbal comprehension index (VCI). The ADHD group had significantly lower scores on performance-based tests of working memory, planning and inhibition, and on EF rating scales. Scores on the cognitive EF working memory, planning and flexibility modestly predicted performance on behavioral EF. The results suggest that the combined use of performance-based tests and rating scales provides valuable complementary information that can improve the assessment of executive domains in ADHD.     

Impairment of executive functions in boys with attention deficit/hyperactivity disorder.

The main aim of the present study is to compare the efficiency of executive control processes in 24 boys with attention deficit/hyperactivity disorder (ADHD) and 58 normal controls of similar age (between 8 and 11 years). Three reaction time (RT) paradigms were utilized: a dual task that requires coordination of two tasks responses, a shift task that makes it necessary to disengage attention from one task and engage into another one, and a stimulus-response spatial compatibility task that requires participants to inhibit a prepotent response. Another purpose of the study is to examine whether Barkley's (1997) executive dysfunction or Sergeant et al.'s (1999) resource allocation/arousal model best account for the behavioral deficits associated with ADHD. Examination of raw RT data showed significantly poorer performance in ADHD children with respect to age-matched controls on both the higher-level cognitive functions of executive control and on lower-level abilities (e.g., speed of processing) of all tasks of this study. However, using proportional transformations of raw RT data, we could demonstrate that, in addition to differences in processing speed, also executive control processes were significantly impaired in children with ADHD.     

Neurobiological models of attention-deficit/hyperactivity disorder: a brief review of the empirical evidence

Attention-deficit/hyperactivity disorder (ADHD) is a psychiatric disorder characterized by inattention, impulsivity, and overactivity that begins in childhood. While considerable research has focused on the neurobiological substrates of this disorder, the specific nature of the brain dysfunction in ADHD has remained elusive. However, early data from pharmacological treatment studies, as well as from basic research in animals and humans, initially led several investigators to develop neurobiological models of ADHD. These models of ADHD and more recent evidence from neuropsychological, neuroimaging, neurochemical, and genetic research are briefly reviewed. While not completely consistent, the empirical data suggest that dysfunction in prefrontal-striatal neural circuits, as well as in brain stem catecholamine systems that innervate these circuits, may underlie the executive function deficits in ADHD.     

Overlapping and Distinct Cognitive Impairments in Attention-Deficit/Hyperactivity and Autism Spectrum Disorder without Intellectual Disability

Attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) are commonly comorbid, share genetic liability, and often exhibit overlapping cognitive impairments. Clarification of shared and distinct cognitive effects while considering comorbid symptoms across disorders has been lacking. In the current study, children ages 7–15 years assigned to three diagnostic groups:ADHD (n?=?509), ASD (n?=?97), and controls (n?=?301) completed measures spanning the cognitive domains of attention/arousal, working memory, set-shifting, inhibition, and response variability. Specific processes contributing to response variability were examined using a drift diffusion model, which separately quantified drift rate (i.e., efficiency of information processing), boundary separation (i.e., speed-accuracy trade-offs), and non-decision time. Children with ADHD and ASD were impaired on attention/arousal, processing speed, working memory, and response inhibition, but did not differ from controls on measures of delayed reward discounting, set-shifting, or interference control. Overall, impairments in the ASD group were not attributable to ADHD symptoms using either continuous symptom measures or latent categorical grouping approaches. Similarly, impairments in the ADHD group were not attributable to ASD symptoms. When specific RT parameters were considered, children with ADHD and ASD shared impairments in drift rate. However, children with ASD were uniquely characterized by a wider boundary separation. Findings suggest a combination of overlapping and unique patterns of cognitive impairment for children with ASD as compared to those with ADHD, particularly when the processes underlying reaction time measures are considered separately.     

Varieties of preschool hyperactivity: multiple pathways from risk to disorder

In this paper we examine the characteristics of preschool attention deficit hyperactivity disorder (ADHD) from both mental disorder and developmental psychopathology points of view. The equivalence of preschool and school-aged hyperactivity as a behavioral dimension is highlighted together with the potential value of extending the use of the ADHD diagnostic category to the preschool period where these behaviours take an extreme and impairing form (assuming age appropriate diagnostic items and thresholds can be developed). At the same time, the importance of identifying pathways between risk and later ADHD is emphasized. Developmental discontinuity and heterogeneity are identified as major characteristics of these pathways. We argue that models that distinguish among different developmental types of early-emerging problems are needed. An illustrative taxonomy of four developmental pathways implicating preschool hyperactivity is presented to provide a framework for future research.     

A dynamic developmental theory of attention-deficit/hyperactivity disorder (ADHD) predominantly hyperactive/impulsive and combined subtypes

Attention-deficit/hyperactivity disorder (ADHD) is currently defined as a cognitive/behavioral developmental disorder where all clinical criteria are behavioral. Inattentiveness, overactivity, and impulsiveness are presently regarded as the main clinical symptoms. The dynamic developmental behavioral theory is based on the hypothesis that altered dopaminergic function plays a pivotal role by failing to modulate nondopaminergic (primarily glutamate and GABA) signal transmission appropriately. A hypofunctioning mesolimbic dopamine branch produces altered reinforcement of behavior and deficient extinction of previously reinforced behavior. This gives rise to delay aversion, development of hyperactivity in novel situations, impulsiveness, deficient sustained attention, increased behavioral variability, and failure to "inhibit" responses ("disinhibition"). A hypofunctioning mesocortical dopamine branch will cause attention response deficiencies (deficient orienting responses, impaired saccadic eye movements, and poorer attention responses toward a target) and poor behavioral planning (poor executive functions). A hypofunctioning nigrostriatal dopamine branch will cause impaired modulation of motor functions and deficient nondeclarative habit learning and memory. These impairments will give rise to apparent developmental delay, clumsiness, neurological "soft signs," and a "failure to inhibit" responses when quick reactions are required. Hypofunctioning dopamine branches represent the main individual predispositions in the present theory. The theory predicts that behavior and symptoms in ADHD result from the interplay between individual predispositions and the surroundings. The exact ADHD symptoms at a particular time in life will vary and be influenced by factors having positive or negative effects on symptom development. Altered or deficient learning and motor functions will produce special needs for optimal parenting and societal styles. Medication will to some degree normalize the underlying dopamine dysfunction and reduce the special needs of these children. The theory describes how individual predispositions interact with these conditions to produce behavioral, emotional, and cognitive effects that can turn into relatively stable behavioral patterns.     

Diagnostic Stability of ADHD in a Community Sample of School-Aged Children Screened for Disruptive Behavior

A large school-based sample of children in Grades 1, 2, 3, and 4 were screened for disruptive behavior and subsequently assessed over a 5-year period for DSM-III-R symptoms of attention deficit hyperactivity disorder (ADHD) and other externalizing and internalizing behavior disorders. Parents completed structured diagnostic interviews in Years 1, 4, and 5, and teachers completed Behavioral Assessment for Children—Teacher Rating Scales behavioral ratings annually. For parent-derived diagnostic data, both inattention and hyperactivity/impulsivity symptom groups declined from Year 1 to Year 4, with hyperactivity showing more significant decline. For teacher-rated behavioral dimensions, the Attention Problems scale declined from Year 1 to Year 3 and stabilized thereafter. The Hyperactivity scale showed stability during the first 3 years before declining in Year 4. Of those children diagnosed with ADHD in Year 1, 69% still met criteria for ADHD in either Year 4 or 5. Persisters were more likely to exhibit coexisting conduct disorder in Year 1 and oppositional defiant disorder in Years 1, 4, and 5. Parents of persisters reported more psychosocial adversity on measures of parenting and marital satisfaction.     

Utility of a CPT in Diagnosing ADHD among a Representative Sample of High-Risk Children: A Cautionary Study

Continuous performance tests (CPTs) are widely used in the assessment and study of attention deficit hyperactivity disorder (ADHD). Although CPTs have reliably found differences between children with ADHD and normal controls, discriminating between children with ADHD and children with subclinical levels of behavioral or cognitive problems is a more clinically relevant and difficult endeavor. Additionally, most studies use convenience samples from clinical care settings that may not represent the ADHD population as a whole. The current study assessed the utility of a clinically used CPT, the Test of Variables of Attention (TOVA), in distinguishing between children with ADHD and children with subclinical levels of attention/behavior problems. Participants constituted a representative sample of elementary school students at high risk for ADHD, including 116 children with ADHD and 51 subclinical controls. Results found no significant differences between the ADHD and subclinical group on CPT variables, and CPT performance did not reliably predict group membership. Implications of the findings are discussed.