This article was downloaded by: [University of Iowa Libraries] On: 11 December 2013, At: 13:54 Publisher: Routledge Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Child Neuropsychology: A Journal on Normal and Abnormal Development in Childhood and Adolescence Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/ncny20 Differences in cognitive control in children and adolescents with combined and inattentive subtypes of ADHD Merete Øieab, Erik Winther Skoglia, Per Normann Andersena, Kjell Tore Hovika & Kenneth Hugdahlc a Innlandet Hospital Trust Lillehammer, Division Mental Health Care, Lillehammer, Norway b Department of Psychology, University of Oslo, Oslo, Norway c Department of Biological and Medical Psychology, University of Bergen, and Division of Psychiatry, Haukeland University Hospital, and KG Jebsen Center for Neuropsychiatric Disorders, Bergen, Norway Published online: 09 Nov 2012. To cite this article: Merete Øie, Erik Winther Skogli, Per Normann Andersen, Kjell Tore Hovik & Kenneth Hugdahl (2014) Differences in cognitive control in children and adolescents with combined and inattentive subtypes of ADHD, Child Neuropsychology: A Journal on Normal and Abnormal Development in Childhood and Adolescence, 20:1, 38-48, DOI: 10.1080/09297049.2012.741224 To link to this article: http://dx.doi.org/10.1080/09297049.2012.741224 PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms- and-conditions Downloaded by [University of Iowa Libraries] at 13:54 11 December 2013 Child Neuropsychology, 2014 Vol. 20, No. 1, 38–48, http://dx.doi.org/10.1080/09297049.2012.741224 Differences in cognitive control in children and adolescents with combined and inattentive subtypes of ADHD Merete Øie1,2, Erik Winther Skogli1, Per Normann Andersen1, Kjell Tore Hovik1, and Kenneth Hugdahl3 1Innlandet Hospital Trust Lillehammer, Division Mental Health Care, Lillehammer, Norway 2Department of Psychology, University of Oslo, Oslo, Norway 3Department of Biological and Medical Psychology, University of Bergen, and Division of Psychiatry, Haukeland University Hospital, and KG Jebsen Center for Neuropsychiatric Disorders, Bergen, Norway The aim of the present study was to investigate the ability of children with attention deficit/hyperactivity disorder-combined subtype (ADHD-C) and predominantly inattentive subtype (ADHD-PI) to direct their attention and to exert cognitive control in a forced attention dichotic lis- tening (DL) task. Twenty-nine, medication-naive participants with ADHD-C, 42 with ADHD-PI, and 40 matched healthy controls (HC) between 9 and 16 years were assessed. In the DL task, two dif- ferent auditory stimuli (syllables) are presented simultaneously, one in each ear. The participants are asked to report the syllable they hear on each trial with no instruction on focus of attention or to explicitly focus attention and to report either the right- or left-ear syllable. The DL procedure is presumed to reflect different cognitive processes: perception (nonforced condition/NF), attention (forced-right condition/FR), and cognitive control (forced-left condition/FL). As expected, all three groups had normal perception and attention. The children and adolescents with ADHD-PI showed a significant right-ear advantage also during the FL condition, while the children and adolescents in the ADHD-C group showed a no-ear advantage and the HC showed a significant left-ear advantage in the FL condition. This suggests that the ADHD subtypes differ in degree of cognitive control impairment. Our results may have implications for further conceptualization, diagnostics, and treatment of ADHD subtypes. Keywords: Dichotic listening; Executive functioning; Attention deficit/hyperactivity disorder; ADHD Downloaded by [University of Iowa Libraries] at 13:54 11 December 2013 subtypes. The project has received financial support from Innlandet Hospital Trust (Grant Number 150170) and the Regional Resource Center for Autism, ADHD, Tourette syndrome and Narcolepsy, Oslo University Hospital (Grant Number 150182). The authors declare no conflict of interest with respect to authorship or publication of this article. Address correspondence to Merete Øie, PhD, Innlandet Hospital Trust Lillehammer, Division Mental Health Care, Anders Sandvigsgate 17, 2609 Lillehammer, Norway. E-mail: [email protected] © 2012 Taylor & Francis COGNITIVE CONTROL IN ADHD SUBTYPES 39 Following the Diagnostic and Statistical Manual of Mental Disorders, text revision (DSM- IV-TR; American Psychiatric Association, 2000), attention deficit/hyperactivity disorder (ADHD) is categorized into three subtypes, including the predominantly inattentive sub- type (ADHD-PI), the predominantly hyperactive/impulsive subtype (ADHD-H), and the combined subtype (ADHD-C). The ADHD-PI subtype shares the inattentiveness of the ADHD-C subtype but lacks the accompanying hyperactivity-impulsivity. The validity of DSM-IV-TR ADHD-H, ADHD-PI, and ADHD-C has been debated for decades (Milich, Balentine, & Lynam, 2001). Children with the ADHD-PI subtype often have later age of referral, are less likely to respond to methylphenidate treatment and are often more easily bored, hypoactive, self-conscious, unmotivated, and shy in contrast to children with ADHD-C (see Adams, Derefinko, Milich, & Fillmore, 2008). Reading and lan- guage deficits are more commonly comorbid with ADHD-PI than with ADHD-C (Weiss, Worling, & Wasdell, 2003). Children with ADHD-PI are significantly less likely to dis- play disruptive behavior compared to children with ADHD-C (Willcutt, Pennington, Chhabildas, Friedman, & Alexander, 1999). They are also more likely than children with ADHD-C to be drowsy, sluggish, and daydreamy; characteristics termed “sluggish cogni- tive tempo” (Hartman, Willcutt, Rhee, & Pennington, 2004). ADHD-PI is more prevalent than ADHD-C in community-based studies but constitutes only 30% of clinic-referred children with ADHD-C, suggesting it may be underrecognized and undertreated (Solanto et al., 2007). It has been proposed that the subtypes are best differentiated by ratings, observations, and tests of cognitive tempo and behavioral impulsivity because traditional neuropsychological methods have not identified critical differences (Solanto et al., 2007). Executive functions (EF) refer to higher order cognitive functions relating to con- trol of thought, action, and emotion (Zelazo & Cunningham, 2007) and are considered key impairments in ADHD (Doyle, 2006). EF encompasses specific neuropsychological functions such as inhibition (cognitive control), working memory, cognitive flexibility, planning, and verbal fluency (Pennington & Ozonoff, 1996). Despite the centrality of EF in ADHD, distinct EF profiles for the two main ADHD subtypes have not been established. In a meta-analytic review of 83 studies with sufficient group sizes and numerous EF tasks, Willcutt, Doyle, Nigg, Faraone, and Pennington (2005) did not find support for reliable EF differences between ADHD-C and ADHD-PI subtypes. The lack of reliable EF differences between ADHD-C and the ADHD-PI subtypes across studies could be due to psychometric methodological aspects, such as a low test specificity characteristic of the typical neuropsychological test and test battery. Further, the traditional neuropsychological test approach typically applies tests that differ in difficulty and require a general understanding of the test situation; two factors that may differentially Downloaded by [University of Iowa Libraries] at 13:54 11 December 2013 affect test scores in clinical groups (Westerhausen & Hugdahl, 2010). Another possible factor is that many prevalent EF tests are highly complex and implicate many differ- ent subprocesses (both EF and non-EF), the so called “task impurity problem” (Miyake, Emerson, & Friedman, 2000). Due to the fact that reading problems, language deficits, and reduced cognitive tempo are more common in ADHD-PI than in ADHD-C, it is important not to use tests or methods that involve multiple executive processes when examining possible EF differences between clinical subtypes. The Dichotic Listening (DL) forced-attention paradigm may reflect different cognitive processes: perception (nonforced condition), attention (forced-right