Article

Validity of the executive function theory of attention-deficit/hyperactivity disorder: A meta-analytic review

University of Denver, Denver, Colorado, United States
Biological Psychiatry (Impact Factor: 10.25). 07/2005; 57(11):1336-46. DOI: 10.1016/j.biopsych.2005.02.006
Source: PubMed

ABSTRACT One of the most prominent neuropsychologic theories of attention-deficit/hyperactivity disorder (ADHD) suggests that its symptoms arise from a primary deficit in executive functions (EF), defined as neurocognitive processes that maintain an appropriate problem-solving set to attain a later goal. To examine the validity of the EF theory, we conducted a meta-analysis of 83 studies that administered EF measures to groups with ADHD (total N = 3734) and without ADHD (N = 2969). Groups with ADHD exhibited significant impairment on all EF tasks. Effect sizes for all measures fell in the medium range (.46-.69), but the strongest and most consistent effects were obtained on measures of response inhibition, vigilance, working memory, and planning. Weaknesses in EF were significant in both clinic-referred and community samples and were not explained by group differences in intelligence, academic achievement, or symptoms of other disorders. ADHD is associated with significant weaknesses in several key EF domains. However, moderate effect sizes and lack of universality of EF deficits among individuals with ADHD suggest that EF weaknesses are neither necessary nor sufficient to cause all cases of ADHD. Difficulties with EF appear to be one important component of the complex neuropsychology of ADHD.

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    • "Accumulating evidence suggests that ASD patients have significantly lower peripheral oxytocin (OXT) levels relative to healthy counterparts, and that the repetitive behavior in ASD is related to abnormalities in the OXT system, abnormalities which can be partially ameliorated by synthetic oxytocin infusion (Modahl et al., 1998; Hollander et al., 2003, 2007). ADHD and ASD are highly comorbid and both disorders share executive function deficits (Willcutt et al., 2005, Corbett et al., 2009; Rommelse et al., 2011), including poor cognitive flexibility (Hill, 2004; Willcutt et al., 2005; Sanders et al., 2008), which has been linked to repetitive behavior in ASD (Yerys et al., 2009). The clinical importance of this behavioral and cognitive overlap has been highlighted by changes to the DSM-5, which now allows co-diagnosis of ADHD and ASD (American Psychiatric Association, 2013). "
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    ABSTRACT: Attention Deficit/Hyperactivity Disorder (ADHD) and autism spectrum disorder (ASD) are highly comorbid, and both disorders share executive function deficits. Accumulating evidence suggests that ASD patients have significantly lower peripheral oxytocin (OXT) levels compared with their normal counterparts, and that the repetitive behavior seen in ASD is related to abnormalities in the OXT system. In this study, we investigated whether serum levels of OXT are altered in pediatric patients with ADHD. We measured serum OXT levels: drug naive ADHD (n=23), medicated ADHD (n=13), and age- and sex- matched, neurotypical controls (n=22). Patients were evaluated using the ADHD-RS. Serum levels of OXT in total subjects with ADHD were significantly decreased compared with those of neurotypical controls, and serum levels of OXT in drug naive ADHD patients were significantly lower than those in medicated ADHD patients. Interestingly, there was a significant negative correlation between serum OXT levels and ADHD-RS total scores, as well as ADHD-RS inattentive scores in all ADHD patients. In conclusion, this study suggests that decreased levels of OXT may play a role in the pathophysiology of patients with ADHD and its inherent inattentiveness. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.
    06/2015; 107. DOI:10.1016/j.psychres.2015.05.029
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    • "ADHD is a syndrome of hyperactivity, impulsivity, and impaired attention (American Psychiatric Association, 2013). Increasingly, ADHD is also recognized as a clinical problem related to underlying deficits in executive function (Willcutt et al. 2005; Mahone & Hoffman, 2007). Executive function is a developmental construct consisting of a combination of domains required for execution of purposeful actions; executive function has been defined as including attention control, cognitive flexibility, goal setting, and information processing (Anderson, 2002; Diamond, 2013). "
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    • "First, and most straight-forwardly, individuals with ADHD may simply fail to suppress the VLFO activity when transitioning from resting to waiting, as is suggested by the DMI hypothesis. This could be the result of failures in executive control (Willcutt et al., 2005) or to problems engaging brain mechanisms implicated in state-to-state switching, (i.e., salience network; Menon and Uddin, 2010). An alternative hypothesis is that, rather than a failure to suppress resting brain activity, excess VLFO activity during waiting represents a positive decision to engage in introspective and self-referential mental activity , such as mind wandering, typically associated with VLFO activity in the core DMN regions (Buckner and Carroll, 2007). "
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