Mechanisms underpinning inattention and hyperactivity: neurocognitive support for ADHD dimensionality. Issue 15 (November 2014)

• Record Type: Journal Article
• Authors: Salum, G. A.; Sonuga-Barke, E.; Sergeant, J.; Vandekerckhove, J.; Gadelha, A.; Moriyama, T. S.; Graeff-Martins, A. S.; Manfro, G. G.; Polanczyk, G.; Rohde, L. A. P.
• Is Part Of: Psychological medicine. Volume 44:Issue 15(2014)
• Page Start: 3189
• Page End: 3201
• Publication Date: 2014-11
• Subjects: Psychiatry -- Periodicals; Medicine and psychology -- Periodicals; Clinical psychology -- Periodicals; 616.89
• DOI: 10.1017/S0033291714000919
• Languages: English
• ISSNs: 0033-2917

Abstract

<abstract abstract-type="normal"> <title> <x content-type="archive" xml:space="preserve">Abstract</x> </title> <sec id="sec_a1"> <title>Background.</title> <p>Taxometric and behavioral genetic studies suggest that attention deficit hyperactivity disorder (ADHD) is best modeled as a dimension rather than a category. We extended these analyses by testing for the existence of putative ADHD-related deficits in basic information processing (BIP) and inhibitory-based executive function (IB-EF) in individuals in the subclinical and full clinical ranges. Consistent with the dimensional model, we predicted that ADHD-related deficits would be expressed across the full spectrum, with the degree of deficit linearly related to the severity of the clinical presentation.</p> </sec> <sec id="sec_a2" sec-type="methods"> <title>Method.</title> <p>A total of 1547 children (aged 6–12 years) participated in the study. The Development and Well-Being Assessment (DAWBA) was used to classify children into groups according to levels of inattention and hyperactivity independently: (1) asymptomatic, (2) subthreshold minimal, (3) subthreshold moderate and (4) clinical ADHD. Neurocognitive performance was evaluated using a two-choice reaction time task (2C-RT) and a conflict control task (CCT). BIP and IB-EF measures were derived using a diffusion model (DM) for decomposition of reaction time (RT) and error data.</p> </sec> <sec id="sec_a3" sec-type="results"> <title>Results.</title> <p>Deficient BIP was found in subjects with minimal, moderate and full ADHD defined in terms of inattention (in both tasks) and hyperactivity/impulsivity dimensions (in the 2C-RT). The size of the deficit increased in a linear manner across increasingly severe presentations of ADHD. IB-EF was unrelated to ADHD.</p> </sec> <sec id="sec_a4" sec-type="conclusion"> <title>Conclusions.</title> <p>Deficits in BIP operate at subclinical and clinical levels of ADHD. The linear nature of this relationship provides support for a dimensional model of ADHD in which diagnostic thresholds are defined in terms of clinical and societal burden rather than representing discrete pathophysiological states.</p> </sec> </abstract>