Advancing the neuroscience of ADHDValidity of the Executive Function Theory of Attention-Deficit/Hyperactivity Disorder: A Meta-Analytic Review
Section snippets
Criteria for a Primary Neurocognitive Deficit
This review examines the validity of the hypothesis that ADHD symptoms arise from a primary deficit in executive control that is necessary and sufficient to cause ADHD. At least four criteria must be met for EF weaknesses to be considered the primary deficit in ADHD.
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Groups with ADHD must consistently exhibit weaknesses on EF measures. In addition, many argue that these weaknesses must remain significant after controlling for potential confounding variables such as age, language, general
Selection of EF Measures
Previous theorists have criticized the construct of EFs as weakly defined and overly broad (Pennington and Ozonoff 1996; Sergeant et al 2003). This assertion is supported by factor analyses of batteries of EF measures (Barkley et al 2001; Miyake et al 2000; Robbins et al 1998; Willcutt et al 2001, 2005b). These studies suggest that EF tasks comprise at least four factors: 1) response inhibition and execution, 2) working memory and updating, 3) set-shifting and task-switching, and 4)
Results of the Meta-Analysis
The meta-analysis found significant differences between groups with and without ADHD on all 13 EF tasks (Table 2). Significant group differences were obtained in 109 of 168 (65%) total comparisons; the weighted mean effect size across all comparisons was .54 (95% CI = .51–.57). Weighted mean effect sizes for all measures fell in the range considered a medium effect (d = .43–.69; Cohen 1988).
Significant group differences were obtained most consistently for stop-signal reaction time (SSRT; 82% of
Potential Moderators of the Relation Between EF and ADHD
The overall results of the meta-analysis indicate that ADHD is associated with weaknesses in several key EF domains; however, interpretation of these results is complicated by differences among the studies in sampling procedures and the diagnostic criteria used to define the groups, as well as the extent to which variables such as intelligence, reading ability, and symptoms of other disorders were controlled. In this section, we briefly examine whether any of these variables influence the
Implications for the EF Theory and Comprehensive Neuropsychologic Models of ADHD
Although ADHD is consistently associated with weaknesses in key EF domains, the magnitude of the group difference on EF measures (d = .4–.6) is much smaller than the group difference in ADHD symptoms (d = 2.5–4.0 in the studies included in the meta-analysis). Moreover, fewer than half of children with ADHD exhibit significant impairment on any specific EF task (Nigg et al 2005, this issue), and correlations between ADHD symptoms and scores on EF tasks are typically significant but small in
Evaluate the Psychometric Characteristics of EF Tasks
Relatively few studies have examined the reliability of EF tasks in children. Although some EF measures appear to have satisfactory psychometric characteristics (Delis et al 2001; Kuntsi et al 2001b), reliability estimates are only moderate (or unknown) for many of the EF measures included in the meta-analysis. Because the reliability of a measure constrains the amount of variance that the measure can explain, measures with weak psychometric characteristics will never yield large effect sizes.
References (147)
- et al.
Behavioral and cognitive subtypes of ADHD
J Am Acad Child Adolesc Psychiatry
(1989) - et al.
Tower of Hanoi performance of retarded young adults and nonretarded children as a function of solution length and goal state
J Exp Child Psychol
(1982) - et al.
Behaviors analogous to frontal lobe dysfunction in children with attention deficit hyperactivity disorder
Arch Clin Neuropsychol
(1989) - et al.
Neuroelectric mapping reveals precursor of stop failures in children with attention deficits
Behav Brain Res
(1998) - et al.
Planning impairments in frontal lobe dementia and frontal lobe lesion patients
Neuropsychologia
(2000) - et al.
Abnormal processing of irrelevant information in attention deficit hyperactivity disorder
Psychiatry Res
(1995) - et al.
The Tower of LondonDXA standardized approach to assessing executive function in children
Arch Clin Neuropsychol
(1998) - et al.
Inhibitory motor control in children with attention-deficit/hyperactivity disorderEvent-related potentials in the stop-signal paradigm
Biol Psychiatry
(2003) - et al.
Altered response control and anterior cingulate function in attention-deficit/hyperactivity disorder boys
Clin Neurophysiol
(2004) - et al.
Molecular genetics of attention-deficit/hyperactivity disorder
Biol Psychiatry
(2005)
A meta-analysis of the sensitivity and specificity of the Stroop Color and Word Test with children
Arch Clin Neuropsychol
Searching for the attention deficit in attention deficit hyperactivity disorderThe case of visuospatial orienting
Clin Psychol Rev
Working memory in childhood-onset schizophrenia and attention deficit/hyperactivity disorder
Psychiatry Res
Co-ordination within and between verbal and visuospatial working memoryNetwork modulation and anterior frontal recruitment
Neuroimage
Validity of DSM-IV attention-deficit/hyperactivity disorder for younger children
J Am Acad Child Adolesc Psychiatry
Performance of children with ADHD on tests of frontal lobe dysfunction
J Am Acad Child Adolesc Psychiatry
Dichotic listening and response inhibition in children with comorbid anxiety disorders and ADHD
J Am Acad Child Adolesc Psychiatry
The unity and diversity of executive functions and their contributions to complex frontal lobe tasksA latent variable analysis
Cog Psychol
Neuropsychological executive functions and DSM-IV ADHD subtypes
J Am Acad Child Adolesc Psychiatry
Causal heterogeneity in attention-deficit/hyperactivity disorderDo we need neuropsychologically impaired subtypes
Biol Psychiatry
Contrasts in memory functions between adolescents with schizophrenia or ADHD
Neuropsychologia
Inhibition in children with attention-deficit/hyperactivity disorderA psychophysiological study of the stop task
Biol Psychiatry
Toward a new neuropsychological model of attention-deficit/hyperactivity disordersubtypes and multiple deficits
Biol Psychiatry
Deficits on subject-ordered tasks after frontal- and temporal-lobe lesions in man
Neuropsychologia
Inhibitory control in children with attention-deficit/hyperactivity disorderEvent related potentials identify the processing component and timing of an impaired right-frontal response-inhibition mechanism
Biol Psychiatry
Phonological processing, not inhibitory control, differentiates ADHD and reading disorder
J Am Acad Child Adolesc Psychiatry
Imaging the mental components of a planning task
Neuropsychologia
A neuropsychological examination of the underlying deficit in attention deficit hyperactivity disorderFrontal lobe versus right parietal lobe theories
Dev Psychol
Electrophysiological evidence of two different types of error in the Wisconsin Card Sorting Test
Neuroreport
Behavioral inhibition, sustained attention, and executive functionConstructing a unified theory of ADHD
Psychol Bull
Comprehensive evaluation of attention deficit disorder with and without hyperactivity as defined by research criteria
J Consult Clin Psychol
Executive functioning, temporal discounting, and sense of time in adolescents with attention deficit hyperactivity disorder (ADHD) and oppositional defiant disorder (ODD)
J Abnorm Child Psychol
Frontal lobe functions in attention deficit disorder with and without hyperactivityA review and research report
J Abnorm Child Psychol
Abnormal executive function in attention deficit hyperactivity disorderThe effect of stimulant medication and age on spatial working memory
Psychol Med
Selective inhibition in children with attention-deficit hyperactivity disorder off and on stimulant medication
J Abnorm Child Psychol
Heart rate variability and sustained attention in ADHD children
J Abnorm Child Psychol
Cognitive and behavioral differences in ADHD boys and girls
J Child Psychiatry Psychol
Attention processes in children with shunted hydrocephalus versus attention deficit-hyperactivity disorder
Neuropsychology
Contextual abnormalities of saccadic inhibition in children with attention deficit hyperactivity disorder
Exp Brain Res
Neuropsychological functioning, motor speed, and language processing in boys with and without ADHD
J Abnorm Child Psychol
Neuroscience of attention-deficit/hyperactivity disorderThe search for endophenotypes
Nat Rev Neurosci
Effects of event rate and display time on sustained attention in hyperactive, normal, and control children
J Abnorm Child Psychol
Frontal lobe disinhibition in attention deficit disorder
Child Psychiatry Hum Dev
A comparison of the cognitive deficits in the DSM-IV subtypes of ADHD
J Abnorm Child Psychol
Statistical Power Analysis for the Behavioral Sciences
Differences between ADHD inattentive and combined types on the CPT
J Psychopathol Behav Assess
Synthesizing Research
The Delis-Kaplan Executive Function System
A meta-analytic review of the sensitivity of the Wisconsin Card Sorting Test to frontal and lateralized frontal brain damage
Neuropsychology
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We were supported in part during the preparation of this manuscript by National Institute of Health Grant Nos. MH 62120 (EGW), MH 63941 (EGW), MH 38820 (BFP), MH 04024 (BFP), MH 59105 (JTN), R21MH/NS66191 (SVF), and K08-MH-66072 (AED).