We used Nunez's physiologically based dynamic theory of EEG to make predictions about a clinical population of children with Attention DeficitHyperactivityDisorder (ADHD) known to have neuronanatomical abnormalities. Analysis of high-density EEG data (long-range coherence) showed expected age-related differences and surprising regional specificity that is consistent with some of the literature in this clinical area.
Attention deficithyperactivitydisorder is a developmental disorderwith an age onset prior to 7 years. Children with ADHD have significantly lower ability to focus and sustain attention and also score higher on impulsivity and hyperactivity. Stimulants, such as methylphenidate, have remained the mainstay of ADHD treatment for decades with evidence supporting their use. However, recent years have seen emergence of newer drugs and drug delivery systems, like osmotic release oral systems and (...) transdermal patches, to mention a few. The use of nonstimulant drugs like atomoxetine and various other drugs, such as a-agonists, and a few antidepressants, being used in an off-label manner, have added to the pharmacotherapy of ADHD. This review discusses current trends in drug therapy of ADHD and highlights the promise pharmacogenomics may hold in the future. (shrink)
Sagvolden, Johansen, Aase, and Russell (Sagvolden et al.) examine attention-deficit/hyperactivitydisorder (ADHD) at levels of analysis ranging from neurotransmitters to behavior. At the behavioral level they attribute aspects of ADHD to anomalies of delay-of-reinforcement gradients. With a normal gradient, responses followed after a long delay by a reinforcer may share in the effects of that reinforcer; with a diminished or steepened gradient they may fail to do so. Steepened gradients differentially select rapidly emitted responses ( (...) class='Hi'>hyperactivity), and they limit the effectiveness with which extended stimuli become conditioned reinforcers, so that observing behavior is less well maintained (attention deficit). Impulsiveness also follows from steepened gradients, which increase the effectiveness of smaller, more immediate consequences relative to larger, more delayed ones. Individuals who vary in the degree to which their delay gradients are steepened will show different balances between hyperactivity and attention deficit. Given the range of ADHD phenomena addressed, it may be unnecessary to appeal to additional behavioral processes such as extinction deficit. Extinction deficit is more likely a derivative of attention deficit, in that failure to attend to stimuli differentially correlated with extinction should slow its progress. The account suggests how relatively small differences in delay gradients early in development might engender behavioral interactions leading to very large differences later on. The steepened gradients presumably originate in properties of neurotransmitter function, but behavioral interventions that use consistently short delays of reinforcement to build higher-order behavioral units as a scaffolding to support complex cognitive and social skills may nonetheless be feasible. Key Words: ADHD; attention deficit; delay gradient; exponential decay; extinction deficit; hyperactivity; impulsiveness; intervention; observing responses; self-control. Footnotes1000 Jeffrey Gray was the BBS Editor for this treatment. When he accepted Sagvolden et al. for publication, he invited Catania, who was one of the reviewers of the original submission, to prepare a precommentary. Com-mentators were then invited to respond to the Sagvolden et al. article, to the Catania precommentary, or to both. (shrink)
Attention-deficit/hyperactivitydisorder (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. Key Words: catecholamine; clumsiness; dopamine; hyperkinesis; hyperkinetic disorder; impulsivity; monoamine; neuromodulator; overactivity; pollutants; reinforcement; reward; verbally governed behavior; soft signs; variability. (shrink)
Prospective follow-up studies have shown that even though some children outgrow the disorder, a childhood diagnosis of attention deficithyperactivitydisorder is clearly a risk factor for a broad range of adverse outcomes, with extremes including drug abuse and juvenile delinquency. This article considers the use of several spectrum concepts and some neuroethical issues. It provides a list of criterion symptoms with a threshold set for the number of symptoms required for categorical diagnoses of (...) disorders. It gives a brief review of some brain imaging and pharmacological treatment studies of ADHD to set the stage for a consideration of brain-specific issues related to neuroethics. Studies using reaction time tasks of cognitive control, response inhibition, and conflict have identified interindividual variance in task performance as one of the most prominent aspects of cognitive deficits related to ADHD. (shrink)
This paper examines two influential theoretical frameworks, set forth by Russell Barkley (1997) and Thomas Brown (2005), and argues that important headway in understanding attention deficithyperactivitydisorder can be made if we acknowledge the way in which human cognition and action are essentially embodied and enactive. The way in which we actively make sense of the world is structured by our bodily dynamics and our sensorimotor engagement with our surroundings. These bodily dynamics are linked to (...) an individual's concerns and felt needs, so that what she attends to in perception, decision-making, and action is partially constituted by her cares and concerns. What I call ?affective framing? engages the whole living body, and ordinarily contributes to attentional focusing, working memory, goal-formulation, and action-monitoring. However, due to affective framing deficits, subjects with ADHD find it difficult to focus their attention, kindle their motivation, and systematically simplify cognitive procedures according to considerations of relevance, salience, and context. Thus, what is impaired in ADHD is not simply a set of executive brain functions, but rather a range of bodily dynamics through which subjects engage with their world. For this reason, intensive behavioral intervention that engages the whole living body may be the most effective, lasting treatment for ADHD. (shrink)
Notwithstanding the many strengths of the dynamic developmental theory, there remain challenges to be overcome before it can be incorporated into a true causal model of attention-deficit/hyperactivitydisorder (ADHD). These include the development of reliable measures of reinforcement delay gradients, the validation of shortened reinforcement delay as an endophenotype, and the integration of this pathway with other potential pathways.
Little is known about how children and adolescents conceptualize psychiatric disorders and psychiatric treatment. In the current study, children and adolescents diagnosed with Attention DeficitHyperactivityDisorder (ADHD) were interviewed about their understanding of ADHD and the medication used to treat their disorder. The participants were all taking Ritalin and ranged in age from 5 to 16 years. With increasing age, children improved in their ability to name their condition and the medication. Latency-aged children (...) often did not perceive Ritalin as helpful while adolescents recognized some value in taking medication. Some of the adolescents were also able to describe medication side effects. The implications of these findings for patient education are discussed. (shrink)
ADHD is a psychiatric disorder characterised by persistent and developmentally inappropriate levels of inattention, impulsivity and hyperactivity. It is known that children with ADHD tend to produce incoherent discourses, e.g. by narrating events out of sequence. Here the aetiology of ADHD becomes of interest. One prominent theory is that ADHD is an executive function disorder, showing deficiencies of planning. Given the close link between planning, verb tense and discourse coherence postulated in van Lambalgen and Hamm (The (...) proper treatment of events, 2004), we predicted specific deviations in the verb tenses produced by children with ADHD. Here we report on an experiment corroborating these predictions. (shrink)
The dynamic developmental theory (DDT) has benefited from the insights of the commentators, particularly in terms of the implications for the proposed steepened delay gradients in attention-deficit/hyperactivitydisorder (ADHD). The introduction of modified memory processes as a basis for the delay gradients improved the links to aspects of ADHD. However, it remains unclear whether the hyperactive-impulsive and inattentive subtypes are separate subgroups or may be explained as different outcomes of the same genetic factors and thus explicable by (...) the same principles. The DDT suggests that altered reinforcement and extinction processes define an endophenotype in ADHD that can be related dimensionally to inattention, hyperactivity, and impulsivity. The relation between the suggested endophenotype, characterized by changes in basic learning mechanisms, and other endophenotypes characterized by delay aversion or response disinhibition, needs to be tested in future studies. (shrink)
Critics of attention-deficit/hyperactivitydisorder (ADHD) have repeatedly argued that there is no proof for the condition being symptomatic of an organic brain disease and that the current "ADHD epidemic" is an expression of medicalization. To this, the supporters of ADHD can retort that the condition is only defined as a mental disorder and not a physical disease. As such, ADHD needs only be a harmful mental dysfunction, which, like other genuine disorders, can have a complex and (...) obscure etiology. This article argues that such a line of argument fails to save ADHD as a valid diagnostic category. Given the general diagnostic logic of the DSM-IV and how ADHD has been defined in terms of everyday (male) child behaviors, there are compelling grounds to disbelieve that ADHD can be a true medical syndrome united by some type of harmful dysfunction. Indeed, strong logical and empirical reasons will be adduced to show that people may qualify for ADHD diagnosis without suffering from any type of underlying pathology. (shrink)
Some commentaries suggest that the attention-deficit/hyperactivitydisorder (ADHD) theory of this condition does not explain enough. Because the theory includes parameters of the delay gradient that vary across individuals and developmental modulation of behavioral outcomes by different environments, it accommodates a wide range of manifestations of ADHD symptoms. Thus, the argument could instead be made that the theory allows too many degrees of freedom. For many purposes, behavior is better defined in terms of function (e.g., consequences) than (...) in terms of structure (e.g., muscle movements), so cognition is treated here as a variety of behavior rather than as a different category of phenomena. The commentaries are discussed in the context of these and other distinctions, including those between association and selection, between operant and respondent behavior, and between fundamental processes and those that are derivative. Other issues include: prosthetic environments, rapidity of developmental change, the concept of inhibition, the form of the delay gradient, and possible directions for experimental research. (shrink)
The reinforcement/extinction disorder hypothesis (Sagvolden et al.) is an important counterweight to the executive dysfunction model of attention-deficit/hyperactivitydisorder (ADHD). However, like that model, it conceptualises ADHD as pathophysiologically homogeneous, resulting from a common core dysfunction. Recent studies reporting neuropsychological heterogeneity suggest that this common core dysfunction may be the scientific equivalent of a red herring.
Attention deficithyperactivitydisorder affects children, adolescents, and adults. Research suggests ADHD has a heritable component. The present article presents and assesses several genetic animal models of ADHD. The paper reviews the literature involving the following genetic animal models of ADHD: the spontaneously hypertensive rat ; the Wistar–Kyoto hyperactive rat; the coloboma mouse; the fast kindling rat; the acallosal mouse; the whirler mouse; and the genetically hypertensive rat. Research investigating animal models of ADHD has concentrated on (...) class='Hi'>hyperactivity, but impulsiveness, learning, and attention are also being examined. The use of animal models allows for the control of possibly confounding variables and has proven very useful in the screening of new therapies. These models have not been shown to be the equivalent of the human disorder, and no model encompasses all of the symptoms of the human disorder, but they are useful nevertheless. (shrink)
O presente artigo teve como objetivo comparar os resultados do desempenho cognitivo de crianças e jovens diagnosticados com os diferentes subtipos do Transtorno do Déficit de Atenção e Hiperatividade (TDAH) na Escala de Inteligência Wechsler para Crianças (WISC-III). Foram analisados dados dos regis..
This paper examines some of the moral panics around hyperactive children, the construction of Attention Deficit-HyperactivityDisorder, and the lure of Ritalin in turning kids identified as at risk into successful, productive individuals. Through a historicization of the child as a psychiatric subject, we try to demonstrate Ritalin's part in the uneven development of modern trends towards the pathologization of everyday life, a developing continuum between normality and abnormality, and an emphasis on the malleability of children and (...) the importance of environment in their upbringing. We conclude that Ritalin is a part of modernity's project of turning people into individualsâin this case, a kind of US transcendence fantasyâwhich, along with discourses and institutions, promises to transform young subjects and biocosmetically alter their futures. (shrink)
Relative to their peers, learning difficulties are more often observable among children with attention deficithyperactivitydisorder – something which may often cause a discrepancy between the “estimated” intelligence of the child and the results that they achieve at school. There are reasons to think that ADHD may be co-occurring with other learning disorders, including specific difficulties with reading and writing typical of developmental dyslexia: this would be the case for 15 to 30 percent (...) of people with ADHD. The aim of this article is to describe the relationship between the typical symptoms of ADHD and of developmental dyslexia in the areas of visual and auditory perception, as well as of motor disorders. Due to the frequent comorbidity of both disorders, they can be defined as combined disorders, which require complex diagnostic and therapeutic procedures. (shrink)
Use of medication for treatment of ADHD (or its historical precursors) has been debated for more than forty years. Reasons for the ongoing differences of opinion are analyzed by exploring some of the arguments for and against considering ADHD a mental disorder. Relative to two important DSM criteria — that a mental disorder causes some sort of harm to the individual and that a mental disorder is the manifestation of a dysfunction in the individual — ADHD’s classification (...) as a mental disorder is found to be contentiously value-laden. The disagreements spill over to reasoning regarding appropriate management, because justification for a drug prescription is in part predicated on the idea that the drugs manage mental disorders. These debates do not appear to be nearing resolution, so individuals offering advice, or trying to decide whether ADHD drugs are appropriate for themselves or their children, may find it helpful to compare the values underlying various perspectives with their own. (shrink)
The use of Ritalin and other stimulant drug treatments for attention-deficithyperactivitydisorder (ADHD) raises distinctive moral dilemmas for parents; these moral dilemmas have not been adequately addressed in the bioethics literature. This paper draws upon data from a qualitative empirical study to investigate parents' use of the moral ideal of authenticity as part of their narrative justifications for dosing decisions and actions. I show that therapeutic decisions and actions are embedded in valued cultural ideals about masculinity, (...) self-actualization and success, as well as in moral conceptions of authenticity and personal freedom. I argue that this investigation of parents' moral justifications and dosing dilemmas raises questions about the validity of authenticity as a transcendent moral principle. Moreover, this study demonstrates that in order to be relevant, bioethical analysis of neurocognitive enhancement must engage with ground-up studies of moral principles and decision-making in context. (shrink)
While there is an increased interest in describing attitudes of teachers, parents and peers towards students with special educational needs in regular education, there is a lack of knowledge about various variables relating to the attitudes of these three groups. The aims of this study are: (1) to examine which variables relate to the attitudes of teachers (N?=?44), parents (N?=?508) and peers (N?=?1113) towards students with Attention Deficit/HyperactivityDisorder, Autistic Spectrum Syndrome or a cognitive disability (...) in regular primary education and (2) to examine whether teachers and parents? attitudes affect the attitudes of peers. An attitude survey was used to assess attitudes and data were analysed by means of multilevel analyses. The variables found in this study relating to attitudes can be used as a foundation to develop interventions to change attitudes. (shrink)
Despite general agreement that altered reward sensitivity is involved in attention-deficit/hyperactivitydisorder (ADHD), a wide range of different alterations has been proposed. We cite work showing abnormal sensitivity to delay of reward, together with abnormal sensitivity to individual instances of reward. We argue that at the cellular level these behavioural characteristics might indicate that dopamine timing is off in children with ADHD.
Aims. Currently, methylphenidate (MPH, trade name Ritalin) is the most widely prescribed medication for attention deficit/hyperactivitydisorder (ADHD). We examined the ability of repeated MPH administration to produce a sensitized appetitive eagerness type response in laboratory rats, as indexed by 50-kHz ultrasonic vocalizations (50-kHz USVs). We also examined the ability of MPH to reduce play behavior in rats which may be partially implicated in the clinical efficacy of MPH in ADHD. Design. 56 adolescent rats received injections of (...) either 5.0 mg/kg MPH, or vehicle each day for 8 consecutive days, and a week later received a challenge injection of either MPH or vehicle. Measurements. Both play behavior (pins) and 50-kHz USVs were recorded after each drug or vehicle administration. Results. MPH challenge produced a substantial 73% reduction in play behavior during the initial treatment phase, and during the last test (1 week post drug), 50-kHz USVs were elevated approximately threefold only in animals with previous MPH experience. Conclusions. These data suggest that MPH treatment may lead to psychostimulant sensitization in young animals, perhaps by increasing future drug-seeking tendencies due to an elevated eagerness for positive incentives. Further, we hypothesize that MPH may be reducing ADHD symptoms, in part, by blocking playful tendencies, whose neuro-maturational and psychological functions remain to be adequately characterized. (shrink)
This study examines the effects of teachers' speech and hand gestures on the task performances of students with Attention‐Deficit/HyperactivityDisorder . Forty‐five 7½‐year‐old students clinically diagnosed with ADHD participated in the study. The students were asked to solve three sets of puzzles. The teachers supported the students in the tasks by using three different scaffolding modalities: speech‐only, gesture‐only and speech in conjunction with gestures. The results indicate that when the teachers used the scaffolding that (...) contained gesture components , the ADHD students were more responsive, focused longer on the tasks and were more successful in completing the tasks. Moreover, teachers' representational and deictic gestures were found to be the most effective gestures in scaffolding. This study suggests that when teachers' hand gestures are used together with speech, they are a powerful pedagogical means to engage ADHD children in tasks. (shrink)
A substantial body of evidence suggests that autobiographical recollection and simulation of future happenings activate a shared neural network. Many of the neural regions implicated in this network are affected in patients with bipolar disorder , showing altered metabolic functioning and/or structural volume abnormalities. Studies of autobiographical recall in BD reveal overgeneralization, where autobiographical memory comprises primarily factual or repeated information as opposed to details specific in time and in place and definitive of re-experiencing. To date, no study (...) has examined whether these deficits extend to future event simulation. We examined the ability of patients with BD and controls to imagine positive, negative and neutral future events using a modified version of the Autobiographical Interview that allowed for separation of episodic and non-episodic details. Patients were selectively impaired in imagining future positive, negative, and neutral episodic details; simulation of non-episodic details was equivalent across groups. (shrink)
Children who presented behaviours characteristic of attention disorder/hyper‐activity deficit , but who were functioning adequately in ordinary schools, were assessed on a range of tests including some focused particularly on cognitive abilities, including verbal and figural aspects of problem solving and creativity. An attempt was made to replicate an earlier study, incorporating refinements to the manner in which pupils were selected from the schools. In spite of cultural differences, the pattern of results substantially duplicated the earlier findings, suggesting (...) a stable pattern of characteristics associated with ADHD and high intelligence. Specifically these children were found to have more mixed laterality and allergies, to gather and use more diverse, nonverbal and poorly focused information, and to show higher figural creativity than did high‐IQ children without attention problems. It was concluded that uncommon information was made use of by ADHD children when exhibiting novelty in nonverbal thinking. This supports Geschwind's prediction that high talent would be found in some types of learning‐disordered individuals. (shrink)