Causal heterogeneity in attention-deficit/hyperactivity disorder: Do we need neuropsychologically impaired subtypes?

Harvard University, Cambridge, Massachusetts, United States
Biological Psychiatry (Impact Factor: 9.47). 07/2005; 57(11):1224-30. DOI: 10.1016/j.biopsych.2004.08.025
Source: PubMed

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.

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    ABSTRACT: This article provides a review of the construct of attention from a non-traditional standpoint. Attention is conceptualized by focusing on the categorical concept of the diagnosis of attention-deficit hyperactivity disorder, large-scale brain network models of functional neuroanatomy, and implications for understanding lateralized hemispheric brain organization. Cortical systems are multifunctional, with certain degrees of specialization, but no cortical region or network supports only one, specific, isolated cognitive process, such as attention. Future implications for clinical practice must focus on connectivity patterns rather than the idea of "domains" or "constructs" when considering attention and other cognitive processes. This has significant implications for the future of neuropsychological assessment and intervention.
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    ABSTRACT: Background This study is the first to evaluate an assessment aid for attention-deficit/hyperactivity disorder (ADHD) according to both Class-I evidence standards of American Academy of Neurology and De Novo requirements of US Food and Drug Administration. The assessment aid involves a method to integrate an electroencephalographic (EEG) biomarker, theta/beta ratio (TBR), with a clinician's ADHD evaluation. The integration method is intended as a step to help improve certainty with criterion E (i.e., whether symptoms are better explained by another condition).Methods To evaluate the assessment aid, investigators conducted a prospective, triple-blinded, 13-site, clinical cohort study. Comprehensive clinical evaluation data were obtained from 275 children and adolescents presenting with attentional and behavioral concerns. A qualified clinician at each site performed differential diagnosis. EEG was collected by separate teams. The reference standard was consensus diagnosis by an independent, multidisciplinary team (psychiatrist, psychologist, and neurodevelopmental pediatrician), which is well-suited to evaluate criterion E in a complex clinical population.ResultsOf 209 patients meeting ADHD criteria per a site clinician's judgment, 93 were separately found by the multidisciplinary team to be less likely to meet criterion E, implying possible overdiagnosis by clinicians in 34% of the total clinical sample (93/275). Of those 93, 91% were also identified by EEG, showing a relatively lower TBR (85/93). Further, the integration method was in 97% agreement with the multidisciplinary team in the resolution of a clinician's uncertain cases (35/36). TBR showed statistical power specific to supporting certainty of criterion E per the multidisciplinary team (Cohen's d, 1.53). Patients with relatively lower TBR were more likely to have other conditions that could affect criterion E certainty (10 significant results; P ≤ 0.05). Integration of this information with a clinician's ADHD evaluation could help improve diagnostic accuracy from 61% to 88%.Conclusions The EEG-based assessment aid may help improve accuracy of ADHD diagnosis by supporting greater criterion E certainty.
    03/2015; DOI:10.1002/brb3.330
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    ABSTRACT: This study aimed to investigate if an executive functions (EF) intervention could promote these skills in individuals with attention deficit and hyperactivity disorder (ADHD). Eighteen children and adolescents, 7-13 years old, divided into experimental (EG, N = 8) and control (CG, N = 10) groups, were assessed in the Block Design and Vocabulary subtests of the WISC III and seven tests of EF. Parents answered two scales, measuring EF and inattention and hyperactivity signs. EG children participated in a program to promote EF in twice-weekly group sessions of one hour each. After 8 months of intervention, groups were assessed again. ANCOVA, controlling for age, intelligence quotient and pretest performance, revealed gains in attention/inhibition and auditory working memory measures for the EG. No effect was found for scales or measures of more complex EF. Results are not conclusive, but they illustrate some promising data about EF interventions in children and adolescents with ADHD.
    Arquivos de neuro-psiquiatria 03/2015; 73(3):227-36. DOI:10.1590/0004-282X20140225 · 0.55 Impact Factor


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