501
|
Stevenson J, Asherson P, Hay D, Levy F, Swanson J, Thapar A, Willcutt E. Characterizing the ADHD phenotype for genetic studies. Dev Sci 2005; 8:115-21. [PMID: 15720369 DOI: 10.1111/j.1467-7687.2005.00398.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The genetic study of ADHD has made considerable progress. Further developments in the field will be reliant in part on identifying the most appropriate phenotypes for genetic analysis. The use of both categorical and dimensional measures of symptoms related to ADHD has been productive. The use of multiple reporters is a valuable feature of the characterization of psychopathology in children. It is argued that the use of aggregated measures to characterize the ADHD phenotype, particularly to establish its pervasiveness, is desirable. The recognition of the multiple comorbidities of ADHD can help to isolate more specific genetic influences. In relation to both reading disability and conduct disorder there is evidence that genes may be involved in the comorbid condition that are different from pure ADHD. To date, progress with the investigation of endophenotypes for ADHD has been disappointing. It is suggested that extending such studies beyond cognitive underpinnings to include physiological and metabolic markers might facilitate progress.
Collapse
Affiliation(s)
- Jim Stevenson
- School of Psychology, University of Southampton, Highfield, Southampton SO17 1 BJ, UK.
| | | | | | | | | | | | | |
Collapse
|
502
|
Castellanos FX, Sonuga-Barke EJS, Scheres A, Di Martino A, Hyde C, Walters JR. Varieties of attention-deficit/hyperactivity disorder-related intra-individual variability. Biol Psychiatry 2005; 57:1416-23. [PMID: 15950016 PMCID: PMC1236991 DOI: 10.1016/j.biopsych.2004.12.005] [Citation(s) in RCA: 382] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2004] [Revised: 11/16/2004] [Accepted: 12/02/2004] [Indexed: 11/21/2022]
Abstract
Intra-individual variability in behavior and functioning is ubiquitous among children with attention-deficit/hyperactivity disorder (ADHD), but it has not been systematically examined or integrated within causal models. This article seeks to provide a conceptual, methodologic, and analytic framework as a foundation for future research. We first identify five key research questions and methodologic issues. For illustration, we examine the periodic structure of Eriksen Flanker task reaction time (RT) data obtained from 24 boys with ADHD and 18 age-matched comparison boys. Reaction time variability in ADHD differed quantitatively from control subjects, particularly at a modal frequency around .05 Hz (cycle length approximately 20 sec). These oscillations in RT were unaffected by double-blind placebo and were suppressed by double-blind methylphenidate. Together with converging lines of basic and clinical evidence, these secondary data analyses support the speculative hypothesis that the increased power of multisecond oscillations in ADHD RT data, and by inference, in attentional performance, represents a catecholaminergic deficit in the ability to appropriately modulate such oscillations in neuronal activity. These results highlight the importance of retaining time-series data and quantitatively examining intra-subject measures of variability as a putative endophenotype for ADHD.
Collapse
Affiliation(s)
- F Xavier Castellanos
- Institute for Pediatric Neuroscience, New York University, Child Study Center, NYU School of Medicine, New York, New York 10016, USA.
| | | | | | | | | | | |
Collapse
|
503
|
Sonuga-Barke EJS. Causal models of attention-deficit/hyperactivity disorder: from common simple deficits to multiple developmental pathways. Biol Psychiatry 2005; 57:1231-8. [PMID: 15949993 DOI: 10.1016/j.biopsych.2004.09.008] [Citation(s) in RCA: 620] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2004] [Revised: 08/30/2004] [Accepted: 09/14/2004] [Indexed: 11/22/2022]
Abstract
Until recently, causal models of attention-deficit/hyperactivity disorder (ADHD) have tended to focus on the role of common, simple, core deficits. One such model highlights the role of executive dysfunction due to deficient inhibitory control resulting from disturbances in the frontodorsal striatal circuit and associated mesocortical dopaminergic branches. An alternative model presents ADHD as resulting from impaired signaling of delayed rewards arising from disturbances in motivational processes, involving frontoventral striatal reward circuits and mesolimbic branches terminating in the ventral striatum, particularly the nucleus accumbens. In the present article, these models are elaborated in two ways. First, they are each placed within their developmental context by consideration of the role of person x environment correlation and interaction and individual adaptation to developmental constraint. Second, their relationship to one another is reviewed in the light of recent data suggesting that delay aversion and executive functions might each make distinctive contributions to the development of the disorder. This provides an impetus for theoretical models built around the idea of multiple neurodevelopmental pathways. The possibility of neuropathologic heterogeneity in ADHD is likely to have important implications for the clinical management of the condition, potentially impacting on both diagnostic strategies and treatment options.
Collapse
Affiliation(s)
- Edmund J S Sonuga-Barke
- Developmental Brain-Behaviour Unit, School of Psychology, University of Southampton, Southampton, United Kingdom.
| |
Collapse
|
504
|
Aron AR, Poldrack RA. The cognitive neuroscience of response inhibition: relevance for genetic research in attention-deficit/hyperactivity disorder. Biol Psychiatry 2005; 57:1285-92. [PMID: 15950000 DOI: 10.1016/j.biopsych.2004.10.026] [Citation(s) in RCA: 417] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2004] [Revised: 09/21/2004] [Accepted: 10/27/2004] [Indexed: 11/26/2022]
Abstract
Psychological functions that are behaviorally and neurally well specified may serve as endophenotypes for attention-deficit/hyperactivity disorder (ADHD) research. Such endophenotypes, which lie between genes and symptoms, may relate more directly to relevant genetic variability than does the clinical ADHD syndrome itself. Here we review evidence in favor of response inhibition as an endophenotype for ADHD research. We show that response inhibition--operationalized by Go/NoGo or Stop-signal tasks--requires the prefrontal cortex (PFC), in particular the right inferior frontal cortex (IFC); that patients with ADHD have significant response inhibition deficits and show altered functional activation and gray matter volumes in right IFC; and that a number of studies indicate that response inhibition performance is heritable. Additionally, we review evidence concerning the role of the basal ganglia in response inhibition, as well as the role of neuromodulatory systems. All things considered, a combined right IFC structure/function/response inhibition phenotype is a particularly good candidate for future heritability and association studies. Moreover, a dissection of response inhibition into more basic components such as rule maintenance, vigilance, and target detection may provide yet better targets for association with genes for neuromodulation and brain development.
Collapse
Affiliation(s)
- Adam R Aron
- Department of Psychology and Brain Research Institute, University of California, Los Angeles, California 90095, USA.
| | | |
Collapse
|
505
|
Nigg JT. Neuropsychologic theory and findings in attention-deficit/hyperactivity disorder: the state of the field and salient challenges for the coming decade. Biol Psychiatry 2005; 57:1424-35. [PMID: 15950017 DOI: 10.1016/j.biopsych.2004.11.011] [Citation(s) in RCA: 336] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2004] [Revised: 09/22/2004] [Accepted: 11/10/2004] [Indexed: 11/20/2022]
Abstract
The past decade has witnessed the establishment of several now well-replicated findings in the neuropsychology of attention-deficit/hyperactivity disorder (ADHD), which have been confirmed by meta-analyses. Progress has been notable from the importing of cognitive science and neuroscience paradigms. Yet these findings point to many neural networks being involved in the syndrome and to modest effect sizes suggesting that any one neuropsychologic deficit will not be able to explain the disorder. In this article, leading theories and key findings are briefly reviewed in four key domains: attention, executive functions, state regulation and motivation, and temporal information processing. Key issues facing the field of neuropsychologic research and theory in ADHD include 1) the need for more integrative developmental accounts that address both multiple neural systems and the socialization processes that assure their development; 2) consideration of multiple models/measures in the same study so as to examine relative contributions, within-group heterogeneity, and differential deficit; and 3) better integration of cognitive process models with affective and temperament theories so that early precursors to ADHD can be better understood. Overall, the field has witnessed notable progress as it converges on an understanding of ADHD in relation to disruption of a multicomponent self-regulatory system. The next era must articulate multipathway, multilevel developmental accounts of ADHD that incorporate neuropsychologic effects.
Collapse
Affiliation(s)
- Joel T Nigg
- Psychology Department, Michigan State University, East Lansing, Michigan 48824-1116, USA.
| |
Collapse
|
506
|
Doyle AE, Willcutt EG, Seidman LJ, Biederman J, Chouinard VA, Silva J, Faraone SV. Attention-deficit/hyperactivity disorder endophenotypes. Biol Psychiatry 2005; 57:1324-35. [PMID: 15950005 DOI: 10.1016/j.biopsych.2005.03.015] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2004] [Revised: 03/09/2005] [Accepted: 03/09/2005] [Indexed: 01/21/2023]
Abstract
Attention-deficit/hyperactivity disorder (ADHD) is a highly heritable disorder with a multifactorial pattern of inheritance. For complex conditions such as this, biologically based phenotypes that lie in the pathway from genes to behavior may provide a more powerful target for molecular genetic studies than the disorder as a whole. Although their use in ADHD is relatively new, such "endophenotypes" have aided the clarification of the etiology and pathophysiology of several other conditions in medicine and psychiatry. In this article, we review existing data on potential endophenotypes for ADHD, emphasizing neuropsychological deficits because assessment tools are cost effective and relatively easy to implement. Neuropsychological impairments, as well as measures from neuroimaging and electrophysiological paradigms, show correlations with ADHD and evidence of heritability, but the familial or genetic overlap between these constructs and ADHD remains unclear. We conclude that these endophenotypes will not be a quick fix for the field but offer potential if careful consideration is given to issues of heterogeneity, measurement and statistical power.
Collapse
Affiliation(s)
- Alysa E Doyle
- Department of Psychiatry, Harvard Medical School, Boston, Massachusetts, USA.
| | | | | | | | | | | | | |
Collapse
|
507
|
Nigg JT, Willcutt EG, Doyle AE, Sonuga-Barke EJS. Causal heterogeneity in attention-deficit/hyperactivity disorder: do we need neuropsychologically impaired subtypes? Biol Psychiatry 2005; 57:1224-30. [PMID: 15949992 DOI: 10.1016/j.biopsych.2004.08.025] [Citation(s) in RCA: 592] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2004] [Revised: 08/20/2004] [Accepted: 08/30/2004] [Indexed: 11/16/2022]
Abstract
Before assigning full etiologic validity to a psycopathologic disorder, disease theory suggests that a causal dysfunction in a mechanism within the affect individuals must be identified. Existing theories on attention-deficit/hyperactivity disorder (ADHD) suggest such dysfunctions in cognitive, neuropsychological, or motivational processes in the child. To date, researchers have tested these theories by comparing groups with DSM-defined ADHD to children without ADHD. Using executive functioning as an illustration of an issue that exists across all such theories, this article describes substantial overlaps in the group performance data. Thus only a subgroup may have executive deficits. Noted are other supportive data suggesting multiple pathways to ADHD. The article explores implications and recommends that future theory and research give more consideration to the probability that only a subset of behaviorally defined children will have a deficit in a given neurocognitive mechanism believed to contribute to the disorder. Creation of a provisional set of criteria in DSM-V for defining an "executive deficit type" could stimulate research to validate the first etiologic subtype of ADHD and spur the development of more sophisticated causal models, which in the longer term may give clinicians ways to target and tailor treatments.
Collapse
Affiliation(s)
- Joel T Nigg
- Department of Psychology, Michigan State University, East Lansing, Michigan 48824, USA.
| | | | | | | |
Collapse
|
508
|
Banaschewski T, Hollis C, Oosterlaan J, Roeyers H, Rubia K, Willcutt E, Taylor E. Towards an understanding of unique and shared pathways in the psychopathophysiology of ADHD. Dev Sci 2005; 8:132-40. [PMID: 15720371 DOI: 10.1111/j.1467-7687.2005.00400.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Most attention deficit hyperactivity disorder (ADHD) research has compared cases with unaffected controls. This has led to many associations, but uncertainties about their specificity to ADHD in contrast with other disorders. We present a selective review of research, comparing ADHD with other disorders in neuropsychological, neurobiological and genetic correlates. So far, a specific pathophysiological pathway has not been identified. ADHD is probably not specifically associated with executive function deficits. It is possible, but not yet established, that ADHD symptoms may be more specifically associated with motivational abnormalities, motor organization and time perception. Recent findings indicating common genetic liabilities of ADHD and other conditions raise questions about diagnostic boundaries. In future research, the delineation of the pathophysiological mechanisms of ADHD needs to match cognitive, imaging and genetic techniques to the challenge of defining more homogenous clinical groups; multi-site collaborative projects are needed.
Collapse
Affiliation(s)
- Tobias Banaschewski
- Child and Adolescent Psychiatry, University of Göttingen, von-Siebold-Str. 5, D-37075 Göttingen, Germany.
| | | | | | | | | | | | | |
Collapse
|
509
|
Sonuga-Barke EJS, Auerbach J, Campbell SB, Daley D, Thompson M. Varieties of preschool hyperactivity: multiple pathways from risk to disorder. Dev Sci 2005; 8:141-50. [PMID: 15720372 DOI: 10.1111/j.1467-7687.2005.00401.x] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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.
Collapse
|
510
|
Coghill D, Nigg J, Rothenberger A, Sonuga-Barke E, Tannock R. Whither causal models in the neuroscience of ADHD? Dev Sci 2005; 8:105-14. [PMID: 15720368 DOI: 10.1111/j.1467-7687.2005.00397.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In this paper we examine the current status of the science of ADHD from a theoretical point of view. While the field has reached the point at which a number of causal models have been proposed, it remains some distance away from demonstrating the viability of such models empirically. We identify a number of existing barriers and make proposals as to the best way for these to be overcome in future studies. These include the need to work across multiple levels of analysis in multidisciplinary teams; the need to recognize the existence of, and then model, causal heterogeneity; the need to integrate environmental and social processes into models of genetic and neurobiological influence; and the need to model developmental processes in a dynamic fashion. Such a model of science, although difficult to achieve, has the potential to provide the sort of framework for programmatic model-based research required if the power and sophistication of new neuroscience technologies are to be effectively exploited.
Collapse
Affiliation(s)
- Dave Coghill
- Department of Psychiatry, University of Dundee, Ninewella Hospital and Medical School, Dundee, DD1 9SY, Scotland, UK.
| | | | | | | | | |
Collapse
|
511
|
Oades RD, Sadile AG, Sagvolden T, Viggiano D, Zuddas A, Devoto P, Aase H, Johansen EB, Ruocco LA, Russell VA. The control of responsiveness in ADHD by catecholamines: evidence for dopaminergic, noradrenergic and interactive roles. Dev Sci 2005; 8:122-31. [PMID: 15720370 DOI: 10.1111/j.1467-7687.2005.00399.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We explore the neurobiological bases of attention deficit hyperactivity disorder (ADHD) from the viewpoint of the neurochemistry and psychopharmacology of the catecholamine-based behavioural systems. The contributions of dopamine (DA) and noradrenaline (NA) neurotransmission to the motor and cognitive symptoms of ADHD (e.g. hyperactivity, variable and impulsive responses) are studied in rodent and primate models. These models represent elements of the behavioural units observed in subjects with ADHD clinically, or in laboratory settings (e.g. locomotion, changed sensitivity/responsivity to novelty/reinforcement and measures of executive processing). In particular, the models selected emphasize traits that are strongly influenced by mesocorticolimbic DA in the spontaneously hypertensive (SHR) and the Naples high excitability (NHE) rat lines. In this context, the mode of action of methylphenidate treatment is discussed. We also describe current views on the altered control by mesolimbic catecholamines of appropriate and inappropriate goal-directed behaviour, and the tolerance or intolerance of delayed reinforcement in ADHD children and animal models. Recent insights into the previously underestimated role of the NA system in the control of mesocortical DA function, and the frontal role in processing information are elaborated.
Collapse
Affiliation(s)
- Robert D Oades
- Clinic for Child and Adolescent Psychiatry, University of Duisburg-Essen, Germany.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
512
|
Sergeant J. EUNETHYDIS -- searching for valid aetiological candidates of Attention-Deficit Hyperactivity Disorder or Hyperkinetic Disorder. Eur Child Adolesc Psychiatry 2004; 13 Suppl 1:I43-9. [PMID: 15322956 DOI: 10.1007/s00787-004-1005-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
BACKGROUND To step up research in ADHD, exchange of ideas, working together on key theoretical models and cooperative studies are necessary. OBJECTIVE To report about a European approach with strong links to the rest of the world. METHOD European Network on Hyperkinetic Disorders (Eunethydis) studies of Attention -- Deficit Hyperactivity Disorder (ADHD) or Hyperkinetic Disorder (HKD) is briefly reviewed in the context of the international effort to discover the aetiology of the disorder. RESULTS There are promising neurobiological, neurophysiological and neuropsychological candidates to explain the nature of ADHD/HKD. CONCLUSION Eunethydis has shown to be a fruitful platform for ADHD research and has good resources for its further development.
Collapse
Affiliation(s)
- Joseph Sergeant
- Free University, Clinical Neuropsychology, De Boelelaan 1105, 1081 HV, Amsterdam, The Netherlands.
| |
Collapse
|
513
|
Masuo Y, Ishido M, Morita M, Oka S, Niki E. Motor activity and gene expression in rats with neonatal 6-hydroxydopamine lesions. J Neurochem 2004; 91:9-19. [PMID: 15379882 DOI: 10.1111/j.1471-4159.2004.02615.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A rat model of a hyperkinetic disorder was used to investigate the mechanisms underlying motor hyperactivity. Rats received an intracisternal injection of 6-hydroxydopamine on post-natal day 5. At 4 weeks of age, the animals showed significant motor hyperactivity during the dark phase, which was attenuated by methamphetamine injection. Gene expression profiling was carried out in the striatum and midbrain using a DNA macroarray. In the striatum at 4 weeks, there was increased gene expression of the NMDA receptor 1 and tachykinins, and decreased expression of a GABA transporter. At 8 weeks, expression of the NMDA receptor 1 in the striatum was attenuated, with enhanced expression of the glial glutamate/aspartate transporter. In the midbrain, a number of genes, including the GABA transporter gene, showed decreased expression at 4 weeks. At 8 weeks, gene expression was augmented for the dopamine transporter, D4 receptor, and several genes encoding peptides, such as tachykinins and their receptors. These results suggest that in the striatum the neurotransmitters glutamate, GABA and tachykinin may play crucial roles in motor hyperactivity during the juvenile period. Several classes of neurotransmitters, including dopamine and peptides, may be involved in compensatory mechanisms during early adulthood. These data may prompt further neurochemical investigations in hyperkinetic disorders.
Collapse
Affiliation(s)
- Yoshinori Masuo
- Human Stress Signal Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan.
| | | | | | | | | |
Collapse
|
514
|
Nigg JT, Blaskey LG, Stawicki JA, Sachek J. Evaluating the Endophenotype Model of ADHD Neuropsychological Deficit: Results for Parents and Siblings of Children With ADHD Combined and Inattentive Subtypes. JOURNAL OF ABNORMAL PSYCHOLOGY 2004; 113:614-25. [PMID: 15535793 DOI: 10.1037/0021-843x.113.4.614] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Neurogenetic models predict neuropsychological weaknesses in the relatives of children with attention-deficit/ hyperactivity disorder (ADHD). The authors examined executive and regulatory measures in 386 relatives (307 parents, 79 siblings) of children with ADHD combined type, ADHD inattentive type, and controls. Predicted deficits were seen on trailmaking (relatives of ADHD combined type only), stop-signal reaction times (relatives of girls only), and response variability (mothers only) but not on naming or output speed. Effects generally held, even with relatives' ADHD status controlled. A neuropsychologically impaired subgroup of children with ADHD had relatives with clear neuropsychological weaknesses. The authors conclude that a neurogenetic model of ADHD etiology is supportable only for a subset of executive functions and that neuropsychological heterogeneity warrants more examination in ADHD.
Collapse
Affiliation(s)
- Joel T Nigg
- Department of Psychology, 115-C Psychology Building, Michigan State University, East Lansing, MI 48824-1116, USA.
| | | | | | | |
Collapse
|
515
|
Yoo HJ, Cho SC, Ha J, Yune SK, Kim SJ, Hwang J, Chung A, Sung YH, Lyoo IK. Attention deficit hyperactivity symptoms and internet addiction. Psychiatry Clin Neurosci 2004; 58:487-94. [PMID: 15482579 DOI: 10.1111/j.1440-1819.2004.01290.x] [Citation(s) in RCA: 245] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The objective of this study was to evaluate the relationship between attention deficit-hyperactivity/impulsivity symptoms and Internet addiction. In total, 535 elementary school students (264 boys, 271 girls; mean age, 11.0 +/- 1.0 years) were recruited. The presence or severity of Internet addiction was assessed by the Young's Internet Addiction test. Parents and teachers of the children completed the DuPaul's attention deficit hyperactivity disorder (ADHD) rating scale (ARS; Korean version, K-ARS) and Child Behavior Checklists. Children with the highest and lowest quartiles in K-ARS scores were defined to be in ADHD and non-ADHD groups, respectively. Five children (0.9%) met criteria for a definite Internet addiction and 75 children (14.0%) met criteria for a probable Internet addiction. K-ARS scores had significant positive correlations with Young's Internet Addiction test scores. The Internet addiction group had higher total scores of K-ARS and ADHD-related subcategories in the Child Behavior Checklists than the non-addiction group. The ADHD group had higher Internet addiction scores compared with the non-ADHD group. Therefore, significant associations have been found between the level of ADHD symptoms and the severity of Internet addiction in children. In addition, current findings suggest that the presence of ADHD symptoms, both in inattention and hyperactivity-impulsivity domains, may be one of the important risk factors for Internet addiction.
Collapse
Affiliation(s)
- Hee Jeong Yoo
- Department of Psychiatry, Gyeongsang National University College of Medicine, Jinju, South Korea
| | | | | | | | | | | | | | | | | |
Collapse
|
516
|
Rhodes SM, Coghill DR, Matthews K. Methylphenidate restores visual memory, but not working memory function in attention deficit-hyperkinetic disorder. Psychopharmacology (Berl) 2004; 175:319-30. [PMID: 15138760 DOI: 10.1007/s00213-004-1833-7] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
RATIONALE Dysfunction of executive neuropsychological performance, mediated by the prefrontal cortex, has been the central focus of recent attention deficit/ hyperkinetic disorder (AD-HKD) research. The role of other potential neuropsychological "risk factors", such as recognition memory, remains understudied. Further, the impact of methylphenidate (MPH) on key neuropsychological processes in AD-HKD remains poorly understood. OBJECTIVES To compare the performance of boys with AD-HKD on a spatial working memory (SWM) task and on two non-working memory tasks [a simultaneous and delayed matching-to-sample task (DMtS) and a pattern-recognition task] with that of healthy boys, and to investigate the impact of acute and chronic MPH on performance of these tasks. METHODS Baseline performance of 75 stimulant-naive boys with AD-HKD was compared with that of 70 healthy boys. The AD-HKD boys were then re-tested following the administration of acute and chronic challenges with MPH (0.3 mg/kg and 0.6 mg/kg) under randomised double-blind placebo controlled conditions. RESULTS Compared with healthy boys, the AD-HKD boys demonstrated performance deficits on all neuropsychological tasks. A single dose of MPH restored performance on the DMtS task but had no impact on the SWM or pattern-recognition tasks. Chronic MPH administration did not alter performance on the SWM task but did improve performance on both the pattern-recognition and DMtS tasks. However, the acute restorative effect of MPH on DMtS diminished with repeated administration. CONCLUSIONS Our results suggest that current conceptualisations of the neuropsychological basis of AD-HKD and the proposed therapeutic mechanisms of MPH require broadening.
Collapse
Affiliation(s)
- Sinead M Rhodes
- Department of Psychiatry, Ninewells Medical School, University of Dundee, Dundee, UK
| | | | | |
Collapse
|
517
|
Karatekin C. A test of the integrity of the components of Baddeley's model of working memory in attention-deficit/hyperactivity disorder (ADHD). J Child Psychol Psychiatry 2004; 45:912-26. [PMID: 15225335 DOI: 10.1111/j.1469-7610.2004.t01-1-00285.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND The integrity of working memory in attention-deficit/hyperactivity disorder (ADHD) was tested within the framework of Baddeley's model. METHODS-1: Buffers and rehearsal mechanisms were assessed by presenting children with or without ADHD (ages 8 to 15) with 1-7 target letters and a probe after 2-10 s. They decided if the probe was the same (verbal task) or in the same location (spatial task) as any of the targets. RESULTS-1: There was no interaction between group and delay or memory load in either task. METHODS-2: The central executive was assessed on a dual task. RESULTS-2: Although children with ADHD did not differ from controls in simple response time (RT) or in digits recalled, they showed greater decrements in RT when performing the 2 tasks concurrently. CONCLUSIONS Findings suggest that children with ADHD (1) do not have generalized impairments in working memory, (2) rehearse verbal and spatial information in the same manner as healthy children, (3) may have an impairment in the central executive component of working memory, which controls ability to divide attention between two tasks.
Collapse
Affiliation(s)
- Canan Karatekin
- Institute of Child Development, University of Minnesota, Minneapolis 55455, USA.
| |
Collapse
|
518
|
Banaschewski T, Roessner V, Uebel H, Rothenberger A. Neurobiologie der Aufmerksamkeitsdefizit-/ Hyperaktivitätsstörung (ADHS). KINDHEIT UND ENTWICKLUNG 2004. [DOI: 10.1026/0942-5403.13.3.137] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Zusammenfassung. Bei der Aufmerksamkeitsdefizit-Hyperaktivitätsstörung (ADHS) handelt es sich um eine in der Kindheit beginnende, klinisch und wahrscheinlich auch ätiologisch heterogene Störung, die durch die Symptom-Trias Unaufmerksamkeit, Hyperaktivität und Impulsivität gekennzeichnet ist. Obwohl die genauen neurobiologischen Ursachen der ADHS weiterhin unbekannt sind, konnten in den Forschungsbereichen Genetik, psychosoziale Umweltfaktoren, Neuropsychologie, Psychophysiologie, funktionelle und strukturelle Bildgebung und Biochemie bedeutende Fortschritte erzielt und verschiedene, hypothetische Modelle zur Pathophysiologie entwickelt werden. Die vorliegende Übersichtsarbeit fasst die aktuellen Erkenntnisse der unterschiedlichen Gebiete zusammen und gibt so eine Zusammenfassung über den aktuellen Wissensstand zur Pathophysiologie der ADHS.
Collapse
Affiliation(s)
| | - Veit Roessner
- Kinder- und Jugendpsychiatrie, Universität Göttingen
| | - Henrik Uebel
- Kinder- und Jugendpsychiatrie, Universität Göttingen
| | | |
Collapse
|
519
|
Winstanley CA, Dalley JW, Theobald DEH, Robbins TW. Fractionating impulsivity: contrasting effects of central 5-HT depletion on different measures of impulsive behavior. Neuropsychopharmacology 2004; 29:1331-43. [PMID: 15054475 DOI: 10.1038/sj.npp.1300434] [Citation(s) in RCA: 265] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Reducing levels of 5-HT in the central nervous system has been associated with increases in impulsive behavior. However, the impulsivity construct describes a wide range of behaviors, including the inability to withhold a response, intolerance to delay of reward and perseveration of a nonrewarded response. Although these behaviors are generally studied using instrumental paradigms, impulsivity may also be reflected in simple Pavlovian tasks such as autoshaping and conditioned activity. This experiment aimed to characterize further the effects of central 5-HT depletion and to investigate whether different behavioral measures of impulsivity are inter-related, thus validating the construct. Rats received intracerebroventricular (ICV) infusions of vehicle (n=10) or the serotonergic neurotoxin 5,7-dihydroxytryptamine (n=12) which depleted forebrain 5-HT levels by about 90%. Lesioned animals showed significant increases in the speed and number of responses made in autoshaping, increased premature responding on a simple visual attentional task, enhanced expression of locomotor activity conditioned to food presentation, yet no change in impulsive choice was observed, as measured by a delay-discounting paradigm. Significant positive correlations were found between responses made in autoshaping and the level of conditioned activity, indicating a possible common basis for these behaviors, yet no correlations were found between other behavioral measures. These data strengthen and extend the hypothesis that 5-HT depletion increases certain types of impulsive responding. However, not all measures of impulsivity appear to be uniformly affected by 5-HT depletion, or correlate with each other, supporting the suggestion that impulsivity is not a unitary construct.
Collapse
|
520
|
Nigg JT, Goldsmith HH, Sachek J. Temperament and attention deficit hyperactivity disorder: the development of a multiple pathway model. JOURNAL OF CLINICAL CHILD AND ADOLESCENT PSYCHOLOGY 2004; 33:42-53. [PMID: 15028540 DOI: 10.1207/s15374424jccp3301_5] [Citation(s) in RCA: 240] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
This article outlines the parallels between major theories of attention deficit hyperactivity disorder (ADHD) and relevant temperament domains, summarizing recent research from our laboratories on (a) child temperament and (b) adult personality traits related to ADHD symptoms. These data are convergent in suggesting a role of effortful control and regulation in the core symptoms of ADHD. Negative approach and anger is also associated with ADHD, but this may be due to the overlap of ADHD and antisocial behavior. Positive approach may be involved in an alternate pathway to ADHD. The involvement of effortful control is congruent with experimental findings of executive functioning deficits in children with ADHD. We hypothesize that, whereas regulation problems may occur in most children with ADHD, a subgroup also may be characterized by positive approach problems and another subgroup by negative approach problems. We conclude with a theorized multiple process developmental model outlining alternate pathways to ADHD that warrant empirical investigation to better resolve etiological heterogeneity in ADHD.
Collapse
Affiliation(s)
- Joel T Nigg
- Psychology Department, Michigan State University, East Lansing 48824-1117, USA.
| | | | | |
Collapse
|
521
|
Cardinal RN, Winstanley CA, Robbins TW, Everitt BJ. Limbic Corticostriatal Systems and Delayed Reinforcement. Ann N Y Acad Sci 2004; 1021:33-50. [PMID: 15251872 DOI: 10.1196/annals.1308.004] [Citation(s) in RCA: 191] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Impulsive choice, one aspect of impulsivity, is characterized by an abnormally high preference for small, immediate rewards over larger delayed rewards, and can be a feature of adolescence, but also attention-deficit/hyperactivity disorder (ADHD), addiction, and other neuropsychiatric disorders. Both the serotonin and dopamine neuromodulator systems are implicated in impulsivity; manipulations of these systems affect animal models of impulsive choice, though these effects may depend on the receptor subtype and whether or not the reward is signaled. These systems project to limbic cortical and striatal structures shown to be abnormal in animal models of ADHD. Damage to the nucleus accumbens core (AcbC) causes rats to exhibit impulsive choice. These rats are also hyperactive, but are unimpaired in tests of visuospatial attention; they may therefore represent an animal model of the hyperactive-impulsive subtype of ADHD. Lesions to the anterior cingulate or medial prefrontal cortex, two afferents to the AcbC, do not induce impulsive choice, but lesions of the basolateral amygdala do, while lesions to the orbitofrontal cortex have had opposite effects in different tasks measuring impulsive choice. In theory, impulsive choice may emerge as a result of abnormal processing of the magnitude of rewards, or as a result of a deficit in the effects of delayed reinforcement. Recent evidence suggests that AcbC-lesioned rats perceive reward magnitude normally, but exhibit a selective deficit in learning instrumental responses using delayed reinforcement, suggesting that the AcbC is a reinforcement learning system that mediates the effects of delayed rewards.
Collapse
Affiliation(s)
- Rudolf N Cardinal
- Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge CB2 3EB, UK.
| | | | | | | |
Collapse
|
522
|
Sonuga-Barke EJS, De Houwer J, De Ruiter K, Ajzenstzen M, Holland S. AD/HD and the capture of attention by briefly exposed delay-related cues: evidence from a conditioning paradigm. J Child Psychol Psychiatry 2004; 45:274-83. [PMID: 14982241 DOI: 10.1111/j.1469-7610.2004.00219.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND The selective attention of children with attention deficit/hyperactivity disorder (AD/HD) to briefly exposed delay-related cues was examined in two experiments using a dot-probe conditioning paradigm. METHOD Colour cues were paired with negatively (i.e., imposition of delay) and positively valenced cues (i.e., escape from or avoidance of delay) during a conditioning phase. These cues were presented alongside neutral cues in a subsequent dot-probe detection phase. RESULTS In experiment 1 teacher-identified children with AD/HD (N = 12), but not controls (N = 12), displayed an attentional bias towards both positively and negatively valenced cues. In experiment 2 children with a diagnosis of hyperkinetic disorder (N = 15), but not controls (N = 15), displayed a bias towards delay-related cues. However, this effect was largely carried by the response to positively valenced cues. CONCLUSIONS These results confirm the dot-probe conditioning paradigm as a useful test of motivational influence on attention. They provide the first evidence of qualitative differences in the attentional style of children with AD/HD and give further support to those theories that highlight the motivational significance of delay in AD/HD.
Collapse
Affiliation(s)
- Edmund J S Sonuga-Barke
- Centre for Research into Psychological Development, Department of Psychology, University of Southampton, Highfield, UK.
| | | | | | | | | |
Collapse
|
523
|
Sergeant JA, Geurts H, Huijbregts S, Scheres A, Oosterlaan J. The top and the bottom of ADHD: a neuropsychological perspective. Neurosci Biobehav Rev 2004; 27:583-92. [PMID: 14624803 DOI: 10.1016/j.neubiorev.2003.08.004] [Citation(s) in RCA: 230] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Five models of attention deficit/hyperactivity disorder (ADHD) are reviewed. It is proposed that the cognitive-energetic model provides a reasonably comprehensive account of ADHD by incorporating the features of both the inhibition and delay aversion models. It is suggested that ADHD can only be accounted for by an analysis at three levels: top-down control, specific cognitive processes and energetic factors. It is argued that a refined and conceptually comprehensive neuropsychological battery is needed to advance research in ADHD. A widely distributed neural network involving frontal, basal ganglia, limbic and cerebellar loci seem implicated in ADHD.
Collapse
Affiliation(s)
- Joseph A Sergeant
- Department of Clinical Neuropsychology, Klinische Neuropsychologie, Vrije Universiteit, Van der Boechorststraat 1, 1081 BT Amsterdam, Netherlands.
| | | | | | | | | |
Collapse
|
524
|
Sonuga-Barke EJS. The dual pathway model of AD/HD: an elaboration of neuro-developmental characteristics. Neurosci Biobehav Rev 2004; 27:593-604. [PMID: 14624804 DOI: 10.1016/j.neubiorev.2003.08.005] [Citation(s) in RCA: 532] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The currently dominant neuro-cognitive model of Attention Deficit Hyperactivity Disorder (AD/HD) presents the condition as executive dysfunction (EDF) underpinned by disturbances in the fronto-dorsal striatal circuit and associated dopaminergic branches (e.g. meso-cortical). In contrast, motivationally-based accounts focus on altered reward processes and implicate fronto-ventral striatal reward circuits and those meso-limbic branches that terminate in the ventral striatum especially the nucleus accumbens. One such account, delay aversion (DEL), presents AD/HD as a motivational style-characterised by attempts to escape or avoid delay-arising from fundamental disturbances in these reward centres. While traditionally regarded as competing, EDF and DEL models have recently been presented as complimentary accounts of two psycho-patho-physiological subtypes of AD/HD with different developmental pathways, underpinned by different cortico-striatal circuits and modulated by different branches of the dopamine system. In the current paper we describe the development of this model in more detail. We elaborate on the neuro-circuitry possibly underpinning these two pathways and explore their developmental significance within a neuro-ecological framework.
Collapse
Affiliation(s)
- Edmund J S Sonuga-Barke
- Department of Psychology, Centre for the Study of Psychological Development, University of Southampton, Southampton S017 1BJ, UK.
| |
Collapse
|
525
|
Cromwell HC, King BH. The Role of the Basal Ganglia in the Expression of Stereotyped, Self-Injurious Behaviors in Developmental Disorders. INTERNATIONAL REVIEW OF RESEARCH IN MENTAL RETARDATION 2004. [DOI: 10.1016/s0074-7750(04)29004-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
|
526
|
Abstract
Response disinhibition is one of several processes that may account for disruptive behavior problems. It is associated with both attention deficits/hyperactivity (ADHD-C) and early onset, unsocialized conduct disorder (CD-E). Response inhibition is not a unitary construct. It is best understood via a dual process model of regulatory control. Executive inhibition refers to deliberate suppression of immediate motor behavior in the service of a distal goal in working memory, with relatively low anxiety activation. It is instantiated in the same frontal-striatal-thalamic neural loops as executive function and corresponds in temperament theory to effortful control. Motivational or reactive inhibition refers to anxiety-provoked interruption of behavior in the context of unexpected, novel, or punishment-cue indicators. Along with reward-response and hostile/angry response it corresponds to reactivity in temperament theory, and invokes limbic responsivity. With regard to these types of inhibitory control, ADHD-combined type is predominantly associated with dysfunctional executive inhibition. CD-E is predominantly associated with dysfunctions in the motivational inhibition process, with smaller, secondary effects in executive control. However, in both syndromes etiological heterogeneity is notable. For example, recent evidence indicates that executive inhibitory control is familial, but characterizes only a subset of children with ADHD-C. Recent dual-process models for both ADHD-C and CD-E are therefore important; they are noted and integrated. Examination of the correlates of behavioral inhibition in the subgroups with these inhibitory deficits may prove fruitful in clarifying the diverse routes to disruptive psychopathology in children.
Collapse
Affiliation(s)
- Joel T Nigg
- Department of Psychology, Michigan State University, East Lansing, MI 48824-1117, USA.
| |
Collapse
|
527
|
Sonuga-Barke EJS, Dalen L, Remington B. Do executive deficits and delay aversion make independent contributions to preschool attention-deficit/hyperactivity disorder symptoms? J Am Acad Child Adolesc Psychiatry 2003; 42:1335-42. [PMID: 14566171 DOI: 10.1097/01.chi.0000087564.34977.21] [Citation(s) in RCA: 150] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To test whether deficits in executive function and delay aversion make independent contributions to levels of attention-deficit/hyperactivity disorder (ADHD) symptoms exhibited by preschool children. METHOD One hundred fifty-six children between 3 and 5.5 years old (78 girls and 78 boys) selected from the community completed an age-appropriate battery of tests measuring working memory, set shifting, planning, delay of gratification, and preference for delayed rewards. Parents completed a clinical interview about their children's ADHD symptoms. RESULTS Analysis of test performance revealed two factors: executive dysfunction and delay aversion. Multivariate analysis demonstrated that when other factors (i.e., age, IQ, and conduct problems) were controlled, executive dysfunction and delay aversion each made significant independent contributions to predictions of ADHD symptoms. CONCLUSIONS Preschool ADHD symptoms are psychologically heterogeneous. Executive dysfunction and delay aversion may represent two distinct and early appearing neurodevelopmental bases for ADHD symptoms.
Collapse
|
528
|
Krause KH, Dresel SH, Krause J, la Fougere C, Ackenheil M. The dopamine transporter and neuroimaging in attention deficit hyperactivity disorder. Neurosci Biobehav Rev 2003; 27:605-13. [PMID: 14624805 DOI: 10.1016/j.neubiorev.2003.08.012] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
There is evidence that abnormalities within the dopamine system in the brain play a major role in the pathophysiology of attention deficit hyperactivity disorder (ADHD). For instance, dopaminergic psychostimulants, the drugs of first choice in ADHD, interact directly with the dopamine transporter (DAT). Molecular genetic studies suggest involvement of a polymorphism of the DAT gene in ADHD. More recent imaging studies show abnormalities in various brain structures, but particularly in striatal regions. In the current paper we review recent studies in this area. First in vivo measurements of DAT with single photon emission computed tomography (SPECT) in ADHD patients revealed an elevation of striatal DAT density. No differences in DAT density between the left and right side and between putamen and caudate nucleus have been found in [99mTc]TRODAT-1 SPECT of ADHD patients. Patients with ADHD and with a history of nicotine abuse both displayed lower values of DAT density in [99mTc]TRODAT-1 SPECT than non-smokers with ADHD. DAT seem to be elevated in non-smoking ADHD patients suffering from the purely inattentive subtype of ADHD as well as in those with the combined or purely hyperactive/impulsive subtype.
Collapse
Affiliation(s)
- Klaus Henning Krause
- Friedrich-Baur-Institute, Ludwig-Maximilians-University, Ziemssenstr. 1a, D-80336 Munich, Germany.
| | | | | | | | | |
Collapse
|
529
|
Dougherty DM, Bjork JM, Harper RA, Marsh DM, Moeller FG, Mathias CW, Swann AC. Behavioral impulsivity paradigms: a comparison in hospitalized adolescents with disruptive behavior disorders. J Child Psychol Psychiatry 2003; 44:1145-57. [PMID: 14626456 DOI: 10.1111/1469-7610.00197] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Behavioral impulsivity paradigms vary widely and studies using these measures have typically relied on a single measure used in isolation. As a result, comparisons between measures are difficult, with little consensus regarding which method may be most sensitive to individual impulsivity differences of different populations. METHOD A single testing session of each of four different impulsivity tasks was completed by two groups of adolescents aged 13-17: hospitalized inpatients with disruptive behavior disorders (DBD; n = 22) and controls (n = 22). Tasks included two rapid-decision (IMT/DMT and GoStop) and two reward-directed (TC and SKIP) impulsivity paradigms. Behavioral testing took place within 3 days of hospitalization for the adolescents with DBD. RESULTS Compared to controls, the DBD group exhibited higher commission error rates, lower inhibited response rates after a stop-signal, and twice as many reward-directed responses even after IQ differences between the groups were taken into account. When the four paradigms were compared, effect-size calculations indicated that the two rapid-decision paradigms were more sensitive to group differences than the reward-directed tasks. CONCLUSIONS Despite the initiation of pharmacotherapy within the first 3 days of hospitalization, in contrast to the control group, the adolescents with DBD performed consistently with what has been operationally defined as impulsivity. Based on these results, these tasks appear to measure similar, but unique components of the impulsivity construct. With further study, laboratory behavioral paradigms may prove to be useful additions to current clinical diagnostic and treatment procedures in a variety of psychiatric populations.
Collapse
Affiliation(s)
- Donald M Dougherty
- Neurobehavioral Research Laboratory and Clinic, Department of Psychiatry and Behavioral Sciences, The University of Texas Health Science Center at Houston, 77030-3406, USA.
| | | | | | | | | | | | | |
Collapse
|
530
|
Winstanley CA, Dalley JW, Theobald DEH, Robbins TW. Global 5-HT depletion attenuates the ability of amphetamine to decrease impulsive choice on a delay-discounting task in rats. Psychopharmacology (Berl) 2003; 170:320-331. [PMID: 12955303 DOI: 10.1007/s00213-003-1546-3] [Citation(s) in RCA: 186] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2003] [Accepted: 05/20/2003] [Indexed: 11/28/2022]
Abstract
RATIONALE Psychomotor stimulant drugs such as methylphenidate and amphetamine decrease impulsive behaviour in attention deficit hyperactivity disorder patients by unknown mechanisms. Although most behavioural effects of amphetamine are attributed to the dopaminergic system, some recent evidence suggests a role for serotonin in this paradoxical "calming" effect. OBJECTIVES To investigate whether forebrain serotonin depletion affects the action of amphetamine in the rat on a delayed reward task where impulsive choice is measured as the selection of a smaller immediate over a larger delayed reward. METHODS . Following behavioural training, rats received i.c.v. infusions of either vehicle (n=10) or the serotonergic neurotoxin 5,7-DHT (n=10). Post-operatively, animals received i.p. d-amphetamine (0.3,1.0,1.5, and 2.3 mg/kg/ml), and d-amphetamine co-administered with the dopamine antagonist cis-z-flupenthixol. RESULTS 5,7-DHT (i.c.v.) itself did not affect choice behaviour, despite depleting forebrain serotonin levels by over 85%. Amphetamine increased choice for the large reward, i.e. decreased impulsivity. This effect was attenuated by 5-HT depletion, particularly in animals showing a high level of impulsive choice. Co-administration of cis-z-flupenthixol (0.125 mg/kg) with d-amphetamine abolished the effect of amphetamine in the lesioned group, whereas this was only partially attenuated in the vehicle control group. CONCLUSIONS These data suggest that the ability of amphetamine to decrease impulsivity is not solely due to its effects on dopaminergic systems, but may also depend on serotonergic neurotransmission.
Collapse
Affiliation(s)
- Catharine A Winstanley
- Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge, CB2 3EB, UK
| | - Jeffrey W Dalley
- Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge, CB2 3EB, UK
| | - David E H Theobald
- Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge, CB2 3EB, UK
| | - Trevor W Robbins
- Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge, CB2 3EB, UK
| |
Collapse
|
531
|
Swanson JM, Volkow ND. Serum and brain concentrations of methylphenidate: implications for use and abuse. Neurosci Biobehav Rev 2003; 27:615-21. [PMID: 14624806 DOI: 10.1016/j.neubiorev.2003.08.013] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
When used to treat children with Attention Deficit Hyperactivity Disorder, methylphenidate (MPH) acts primarily by blocking the dopamine (DA) transporter (DAT) and increasing extracellular DA in the striatum. This is strikingly similar to the mechanism of action of cocaine, a primary stimulant drug of abuse. When administered intravenously, MPH like cocaine has reinforcing effects (euphoria) at doses that exceed a DAT blockade threshold of 60%. When administered orally at clinical doses, the pharmacological effects of MPH also exceed this threshold, but reinforcing effects rarely occur. Here we discuss the pharmacokinetic properties of MPH in serum (and in brain) that differ for oral and intravenous routes of administration and the importance of acute tolerance in determining pharmacodynamic effects in clinical use and illegal abuse. We suggest that intravenous administration of MPH mimics the rapid phasic cell firing of DA neurons, which may be a critical factor associated with reinforcing effects and abuse, while oral administration of MPH mimics the tonic DA cell firing, which may be a critical factor associated with clinical effects.
Collapse
Affiliation(s)
- J M Swanson
- UCI: Child Development Center, University of California, 19722 MacArthur Boulevard, Irvine, CA 92612-4480, USA.
| | | |
Collapse
|
532
|
Cools R, Barker RA, Sahakian BJ, Robbins TW. L-Dopa medication remediates cognitive inflexibility, but increases impulsivity in patients with Parkinson's disease. Neuropsychologia 2003; 41:1431-41. [PMID: 12849761 DOI: 10.1016/s0028-3932(03)00117-9] [Citation(s) in RCA: 376] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In the current study we investigated the role of dopamine in attentional and socio-emotional functioning by examining effects of withdrawing dopaminergic medication in patients with Parkinson's disease (PD). Patients "on" medication exhibited abnormal betting strategies on a task of decision-making, reflecting impulsive behaviour and/or delay aversion, whilst the same patients "off" medication exhibited abnormally increased switch costs when switching between two tasks, reflecting attentional inflexibility. Hence, these data replicate and extend previous findings that dopaminergic medication improves or impairs cognitive performance depending on the nature of the task and the basal level of dopamine function in underlying cortico-striatal circuitry.
Collapse
Affiliation(s)
- Roshan Cools
- Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge CB3 9DF, UK.
| | | | | | | |
Collapse
|
533
|
Burton C, Stevenson JC, Williams DC, Everson PM, Mahoney ER, Trimble JE. Attention-deficit hyperactivity disorder (AD/HD) and fluctuating asymmetry (FA) in a college sample: an exploratory study. Am J Hum Biol 2003; 15:601-19. [PMID: 12953172 DOI: 10.1002/ajhb.10179] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Departures from normal development can be partly assessed by measuring fluctuating asymmetry (FA), that is, differences from perfect symmetry in traits that display bilateral symmetry. Attention-deficit hyperactivity disorder (AD/HD), one of the most common psychiatric conditions, is diagnosed if there are developmentally inappropriate levels of inattention, hyperactivity, and impulsivity. The objective here is to measure whether AD/HD behaviors positively correlate with FA in head, hands, and fingerprints of a sample of college students (n = 176, 57 male, 119 female) not selected for AD/HD. FA was measured as the absolute value of the difference between right and left sides divided by group mean trait size. Average FAs (mean, SE) were lowest for finger lengths (e.g., male, 3rd, 0.011 +/- 0.001; female, 3rd, 0.012 +/- 0.001) and highest for digit ridge counts (e.g., male, 5th, 0.075 +/- 0.007; female, 2nd, 0.069 +/- 0.005). Average FAs were similar between the sexes and only one facial measure and the facial index (summed FAs) differed significantly between the sexes (F > M). The scores for measures of the adult AD/HD behavioral assessment instrument, the Wender Utah Rating Scale (WURS) were high overall in this sample and males exhibited higher rates of symptoms than females. A Rasch measurement model analysis of individual responses to the WURS produced a true interval score for each person that is a measure of individual "AD/HDness." FA indices were then regressed on Rasch scores. A univariate analysis of all the variables demonstrated a significant interaction of sex. Hand, Dermatoglyphic, Face, and Total Indices were then regressed by sex on the Rasch values of "AD/HDness." Only in males was there a trend for the Dermatoglyphic Index (F(1,55) = 3.627, P = 0.062) and Total Index (F(1,55) = 3.811, P = 0.056) to increase as AD/HDness increases.
Collapse
Affiliation(s)
- C Burton
- Department of Anthropology, Western Washington University, Bellingham, Washington 98225, USA
| | | | | | | | | | | |
Collapse
|
534
|
Abstract
The paper by Gillberg, 'ADHD and DAMP', provides an analysis of the scientific status of the concept of Deficits in Attention Motor Control and Perception (DAMP) in the light of the overlap between Attention Deficit/Hyperactivity Disorder (AD/HD) and Developmental Co-ordination Disorder (DCD), and the current uncertainty surrounding the significance of AD/HD - DCD co-morbidity.
Collapse
Affiliation(s)
- Edmund J S Sonuga-Barke
- Centre for Research into Psychological Development, University of Southampton, Southampton S017 1BJ, UK
| |
Collapse
|
535
|
McDonald J, Schleifer L, Richards JB, de Wit H. Effects of THC on behavioral measures of impulsivity in humans. Neuropsychopharmacology 2003; 28:1356-65. [PMID: 12784123 DOI: 10.1038/sj.npp.1300176] [Citation(s) in RCA: 239] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This study investigated the acute effects of delta(9)-tetrahydrocannabinol (THC) on four behavioral measures of impulsivity in recreational marijuana users. Although impulsive behavior has been studied using several different measures of impulsivity, few studies have utilized more than one of these measures on a single cohort. In this study, 37 healthy men and women participated in three sessions, in which they received capsules containing placebo, 7.5, or 15 mg THC in randomized order under double-blind conditions. Subjects were tested on the following four tasks: the Stop task, which measures the ability to inhibit a prepotent motor response; a Go/no-go task; a Delay discounting task, which measures the value of delayed or uncertain reinforcers; and a time estimation task, which measures alterations in time perception through a time reproduction procedure. Subjects also completed mood questionnaires and general measures of performance. THC produced its expected effects on subjective measures including increases in ARCI euphoria and marijuana scales. THC increased impulsive responding on the Stop task but did not affect performance on either the Go/no-go or Delay or Probability discounting tasks. On the time reproduction task, THC increased estimates of the duration of short intervals while not affecting estimates of longer intervals. There were no significant correlations between the four tasks either before or after drug administration. These results suggest that THC may increase certain forms of impulsive behavior while not affecting other impulsive behaviors. The dissociations between the four measures of impulsivity suggest that impulsivity is an assemblage of distinct components rather than a unitary process.
Collapse
Affiliation(s)
- Jennifer McDonald
- Department of Psychiatry, The University of Chicago, Chicago, IL 60637, USA
| | | | | | | |
Collapse
|
536
|
Abstract
We suggest that the core feature of bipolar disorder (BPD) is marked state fluctuations. The pathophysiology of switches into depressed, irritable, and extreme positive valence states requires study, with the latter deserving particular focus because it represents a pathognomonic feature of BPD in both adults and children. Hypotheses regarding the pathophysiology of pediatric BPD must account for these marked state fluctuations as well as for specific developmental aspects of the illness. These developmental aspects include marked irritability (in addition to euphoria and depression) and very rapid cycles, along with high rates of attention-deficit/hyperactivity disorder. We review research on neural mechanisms underlying positive valence states and state regulation, focusing on those data relevant to BPD and to development. Researchers are beginning to explore the response of manic patients and control subjects to positive affective stimuli, and considerable research in both nonhuman primates and humans has focused on the cortico-limbic-striatal circuits mediating responses to rewarding stimuli. In control subjects, positive affect affects cognition, and data indicate that prefrontal electroencephalogram asymmetry may differ between control subjects with consistently positive affect and those with more negative affect; however, this latter generalization may not apply to adolescents. With regard to the pathophysiology of state switching in pediatric BPD, data in control subjects indicating that attention regulation plays a role in emotion regulation may be germane. In addition, research detailing physiologic and psychological responses to negative emotional stimuli in bipolar patients and control subjects may increase our understanding of the mechanisms underlying both irritability and rapid cycling seen in children with BPD. Potential foci for research on the pathophysiology of pediatric BPD include reactivity to standardized positive and negative emotional stimuli, and the interaction between emotion regulation and attentional processes.
Collapse
Affiliation(s)
- Ellen Leibenluft
- Mood and Anxiety Program, National Institute of Mental Health, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892, USA
| | | | | |
Collapse
|
537
|
Sonuga-Barke EJS, Dalen L, Daley D, Remington B. Are planning, working memory, and inhibition associated with individual differences in preschool ADHD symptoms? Dev Neuropsychol 2003; 21:255-72. [PMID: 12233938 DOI: 10.1207/s15326942dn2103_3] [Citation(s) in RCA: 147] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
The association between executive function (EF; planning, working memory, and inhibition) and individual differences in symptoms of attention deficit hyperactivity disorder (ADHD) was explored in a sample of preschool children. One hundred sixty children (between the ages of 3 years, 0 months and 5 years, 6 months), selected so as to oversample high ADHD scorers, performed 3 tasks previously shown to measure planning (Tower of London), working memory (Noisy Book) and inhibition ("Puppet Says..."). EF measures were reliable (kappa > .77) and were correlated with IQ (rs > .38) and age (rs > .59). Once IQ and age were controlled, planning and working memory (r = .41) were correlated. Planning and working memory were not correlated with inhibition (rs < .20). There was no association between ADHD and working memory or planning (rs < .12). There was a significant negative association between ADHD and conduct problems and inhibition (r = -.30 and r = -.25, respectively). Only the link with ADHD persisted after the effects of other factors were controlled for in a multiple regression. Specific deficits in inhibitory control rather than general EF deficits are associated with ADHD in the preschool period. This association is linear in nature, supporting the idea that ADHD is better seen as a continuum rather than a discrete category. This association provides evidence for Barkley's (1997) view that ADHD is underpinned by inhibitory deficits in the preschool period.
Collapse
Affiliation(s)
- Edmund J S Sonuga-Barke
- Centre for Research Into Psychological Development, Department of Psychology, University of Southampton, England.
| | | | | | | |
Collapse
|
538
|
Castellanos FX, Tannock R. Neuroscience of attention-deficit/hyperactivity disorder: the search for endophenotypes. Nat Rev Neurosci 2002; 3:617-28. [PMID: 12154363 DOI: 10.1038/nrn896] [Citation(s) in RCA: 1156] [Impact Index Per Article: 50.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- F Xavier Castellanos
- New York University Child Study Center, 577 First Avenue, CSC 204, New York, New York 10016-6404, USA.
| | | |
Collapse
|
539
|
Sonuga-Barke EJS. Interval length and time-use by children with AD/HD: a comparison of four models. JOURNAL OF ABNORMAL CHILD PSYCHOLOGY 2002; 30:257-64. [PMID: 12041711 DOI: 10.1023/a:1015154829796] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Predictions made by 4 competing models of time use by children with AD/HD were tested using a computerized version of the Matching Familiar Figures Test in 2 studies. In Study 1 teacher-identified AD/HD children (N = 10) and non-AD/HD controls (N = 10) completed the task under 3 different trial duration conditions (5, 10, and 15 s). In Study 2 the same task was completed by a group of children with a diagnosis of Hyperkinetic Disorder (N = 12) and controls (N = 12). In both studies AD/HD children performed poorly on trials of both 5- and 15-s duration but as well as controls on the 10-s trials. This quadratic function provided support for the State Regulation Deficit model of time use in AD/HD. The value of tailoring the temporal features of learning contexts to the conceptual style of AD/HD children is discussed.
Collapse
Affiliation(s)
- Edmund J S Sonuga-Barke
- Centre for Research into Psychological Development, Department of Psychology, University of Southhampton at Highfield, England.
| |
Collapse
|