!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"#$#%!&#'$%#(!)'!*+#(,-&,'$!*+.+! ! MOTOR PERFORMANCE IN ADOLESCENTS WITH ADHD by Emma McIlveen-Brown A thesis submitted in conformity with the requirements for the degree of the Master of Arts Department of Human Development and Applied Psychology Ontario Institute for Studies in Education / University of Toronto Copyright 2010 ! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"#$#%!&#'$%#(!)'!*+#(,-&,'$!*+.+! Motor Performance in Adolescents with ADHD Emma McIlveen-Brown Master’s of Arts, 2010 School and Clinical Child Psychology Program Department of Human Development and Applied Psychology, University of Toronto / Ontario Institute for Studies in Education Abstract This thesis presents two manuscripts on motor control in ADHD. The first is a literature review that identifies fine motor control and postural stability as areas of robust abnormality in ADHD. Further, the review suggests that motor performance in adolescence has been understudied, and reveals a paucity of data on sex differences. The second study is an empirical assessment of postural control and fine motor skills in an adolescent ADHD sample, which investigated potential sex differences. This latter study revealed that males with ADHD were especially impaired on fine motor tasks, whereas females with the disorder were particularly impaired on tasks of postural stability. Deficits were most prominent under conditions where visual information was removed, across genders. It is unclear whether motor performance deficits are central features of ADHD or instead artifacts of overlap with Developmental Coordination Disorder and other psychiatric comorbidities. ! ! //! ! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"#$#%!&#'$%#(!)'!*+#(,-&,'$!*+.+! Acknowledgements I would like to thank Dr. Rosemary Tannock for all of her advice on the many successive drafts of this manuscript. She is an inspirational role model of as both an astute scientist and a consistently thoughtful and lovely human being. I feel very privileged to have had her advise my research. I would also like to thank Dr. Maureen Dennis, another important mentor, for volunteering her comments at the early stages of data analysis. As well, thank you to Dr. Rhonda Martinussen for acting as a second reader on the manuscript. I would also like to thank Doctors Maggie Toplak, Karen Ghelani and Umesh Jain for their work on the YEARS data set on which this research is based. As well, I would a like to thank all of the adolescents who volunteered their time in support of this research. Finally, to my friends and family, thank you for being yourselves and for being there to inspire me. ! ! ///! ! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"#$#%!&#'$%#(!)'!*+#(,-&,'$!*+.+! Table of Contents Page Table of Contents i Acknowledgements ii Abstract iii Chapter One: Rationale and Overview of Thesis Research 1-8 1.1. Overview of Research 2 1.1. Clinical Phenotype of ADHD and DCD 2-5 1.1.1 ADHD 2-3 1.1.2 DCD 3-4 1.1.3 ADHD and DCD: Areas of Overlap 4-5 1.1.4 Clinical Significance of Motor Dysfunction 5 1.2 Theoretical Perspectives 6 1.2.1 Beyond Executive Dysfunction 6 1.2.2 Insights from Brain Imaging Studies of Motor 7 Function in ADHD 1.3 Rationale for the Present Study 7-8 Chapter Two: Motor Performance in Attention Deficit/Hyperactivity 9-33 Disorder (ADHD): A systematic review 2.1 Abstract 10 2.2 Rationale 11-12 2.3 Systematic Review 12-15 2.4. Conclusions 15 2.5 Figures 16 2.6 Supplemental Material: Systematic Review Table 17-33 Chapter Three: Poor Fine Motor Control and Postural Stability in 34 Adolescents with ADHD 3.1 Abstract 35 3.2 Introduction 36-37 3.3 Methods 37-42 3.4 Results 42-43 3.5 Discussion 43-47 3.6 Tables 48-53 3.7 Supplemental Material: Perinatal Risk Index 53-55 Chapter Four: General Discussion 56-58 4.1 General Conclusions 57-58 4.2 Future Directions 60 References 61-71 ! ! /0! ! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"#$#%!&#'$%#(!)'!*+#(,-&,'$!*+.+! CHAPTER ONE Rationale and Overview of Thesis Research ! ! 1! ! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"#$#%!&#'$%#(!)'!*+#(,-&,'$!*+.+! 1.1 Overview of Research My research investigates sex differences in motor skills in adolescents with Attention Deficit/Hyperactivity Disorder (ADHD). Notably, motor skills are defining features of Developmental Coordination Disorder (DCD), with which ADHD is frequently comorbid. Accordingly, in this chapter which provides the background for my research, I first describe the ADHD and DCD phenotypes, and their comorbidity. Next I provide a theoretical perspective for my research and conclude by summarizing the rationale for my studies. ! 1.2 Clinical Phenotype of ADHD and DCD 1.2.1 Attention Deficit Disorder Attention-Deficit/Hyperactivity Disorder, (ADHD; American Psychiatric Association, 2000) is a prevalent psychiatric disorder that occurs in approximately 5% of children and 4% of adults (Polanczyk & Jensen, 2008), and is linked with poor academic, social, and occupational outcomes (Bussing, Mason, Bell, Porter, & Garvan, 2010; Loe & Feldman,2007 ). The disorder is more commonly diagnosed in boys than girls with sex ratios varying form 9:1 to 2:1 depending on subtype, age, and referral source (Ramtekkar, Reiersen, Todorov & Todd, 2010). To meet diagnostic criteria for ADHD, the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV TR; American Psychiatric Association, 2000) requires the individual to show at least six symptoms of either inattention (i.e. seems not to listen when spoken to, has difficulty organizing tasks) or hyperactivity (i.e. is often “on the go, talks excessively) which have persisted over a period of at least six months and cause clinically significant impairment in at least two settings (e.g. home and school). Further, these symptoms must have first ! ! 2! ! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"#$#%!&#'$%#(!)'!*+#(,-&,'$!*+.+! presented before the age of 7. Although excessive motor activity is a defining feature of ADHD, there is no reference made to either fine or gross motor skills in the DSM-IV. ADHD symptoms, especially those of hyperactivity, tend to decline through late childhood and adolescence (American Psychiatric Association, 2000). However, according to a longitudinal follow-up study of childhood ADHD diagnoses, almost half of the teens assessed retained their ADHD diagnoses (Bussing et al., 2010). Moreover, regardless of later diagnosis, childhood ADHD was associated with poor educational outcomes, increased probability of later diagnosis with another DSM-IV disorder and reduced quality of life. ADHD diagnosis is associated with high rates of comorbity with mood disorders (e.g. Anxiety Disorder, Depression); disruptive behaviour disorders (e.g. Oppositional Defiant Disorder, Conduct Disorder) and other neurodevelopmental disorders including those of learning, language and motor coordination (Biederman, Newcorn & Sprich, 1991). Comorbidity between ADHD and Developmental Coordination Disorder has important clinical and research implications and is discussed in the following sections. 1.2.2 Developmental Coordination Disorder Developmental Coordination Disorder (DCD) is prevalent disorder of motor coordination most commonly diagnosed in childhood (American Psychiatric Association, 2000). While prevalence rates are estimated to be as high as 6%, they vary greatly according to the definition of the disorder. For instance, one study cited prevalence rates for moderate DCD at 8.9% (Kadesjo & Gillberg, 1999), whereas another using a more stringent 5th percentile cutoff, cited rates at 1.8% (Lingam, Hunt, Golding, Jongmans, & Emond, 2009). DCD is diagnosed when motor coordination skills are significantly below ! ! 3! ! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"#$#%!&#'$%#(!)'!*+#(,-&,'$!*+.+! those expected for one’s age and developmental level and deficits interfere with the performance of activities of daily activities living. Diagnosis of DCD typically involves clinical observation and direct assessment of motor skills using a standardized tool, such as the Movement Assessment Battery for Children (Henderson & Sugden, 1992; also see reviews of tools by Slater, Hillier & Civetta, 2010). Questionnaires, such as the Developmental Coordination Disorder Questionnaire (DCD-Q; Wilson et al. 2009) are often used as a screening tool. The presentation of the disorder varies across the life span. In early years deficits may present as delays in achieving motor milestones (e.g., walking, crawling), whereas in later years the may present as "clumsiness" poor handwriting or lack of sport ability. In order to receive DSM-IV diagnosis motor coordination deficits must cause significant impairment and must not result from another more general medical condition. While most children outgrow motor coordination deficits (American Psychiatric Association, 2000), the trajectory of the disorder is variable and may persist through adolescence and adulthood (Cairney, Hay JA, Veldhuizen, Missiuna & Faught, 2010). Moreover, its deleterious impact on participation in organized and free-play activities appears to be more serious and persistent in females compared to males (Cairney et al., 2010). 1.1.3 ADHD and DCD: Rates of Comorbidity Rates of co-morbidity between ADHD and DCD are cited to be as high as 50% (Kadesjo & Gillberg, 1999) and genetic findings indicate shared heritable neuropsychological characteristics between the two disorders (Fliers et al., 2009). According to the DSM-IV TR (American Psychiatric Association, 2000) however, motor coordination and attention deficits are viewed as unrelated and distinct constructs. It is ! ! 4! ! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"#$#%!&#'$%#(!)'!*+#(,-&,'$!*+.+! suggested that: “individuals with Attention-Deficit/Hyperactivity Disorder may fall, bump into things, or knock things over, but [that] this is usually due to distractibility and impulsiveness rather than to a motor impairment” (American Psychiatric Association, 2000; pg 57). However, recent findings question this assumption and indicate that motor coordination deficits observed in ADHD cannot be completely accounted for by deficient attentional processes ((Miyahara, Piek, & Barrett, 2008). This evidence suggests that motor deficits, at least in a subset of the ADHD population, are core features associated with the disorder. 1.1.4 Clinical Significance of Motor Dysfunction The co-occurrence of motor and attention dysfunction has been associated with negative clinical outcomes above and beyond those associated with either disorder in isolation (Gillberg & Kadesjo, 2003). Motor coordination problems are likely important factors mediating links between ADHD and poor physical activity outcomes. Children with ADHD tend to have more adipose tissue and poorer cardiovascular performance than controls (Harvey & Reid, 2003). Motor skill deficits in children and adolescents are also associated self-perceptions of with reduced physical and academic competence and with feelings of unhappiness with one’s appearance (Piek, Baynam, & Barrett, 2006). Motor coordination problems may also play a role in the increased risks for personal injury and adverse driving outcomes that are associated with the disorder. Children with ADHD are more than twice as likely than their non-ADHD peers to have sustained a severe injury requiring hospitalization (DiScala, Lescohier, Barthel, & Li, 1998) and adults with the disorder are two to four times more likely than controls to have serious motor vehicle accidents (Barkley, 1997). ! ! 5! ! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"#$#%!&#'$%#(!)'!*+#(,-&,'$!*+.+! 1.2 Theoretical Perspectives 1.2.1 Beyond Executive Dysfunction Individuals with ADHD tend to have difficulty with aspects of higher-order cognitive functioning. For instance, they often have trouble regulating their levels of affect, arousal and motivation and organizing their thoughts and behavior (Barkley, 1997). As such, most research on the disorder has assessed abnormalities in higher-order thought processes. These processes, which can be broadly grouped under the rubric of executive function (EF), are suggested to exert cognitive control over multiple domains (e.g. language, visuospatial functions, memory, emotion and motor skills) in service of achieving a given goal (Zelazo et al., 2003). While there is extensive evidence of executive impairment in ADHD (Barkley, 1997), a recent meta analysis (Willcutt, Doyle, Nigg, Faraone, & Pennington, 2005) suggests that patterns of impairment are variable. Of a set of thirteen EF tasks studied, ADHD groups exhibited significant levels of impairment, with moderate effect size, for all tasks. However, only 16-51% of ADHD children were impaired on any single measure. Further, a substantial portion (21%) of children with ADHD did not show deficits on any of the measures. These findings led the authors to suggest that executive deficits are “neither necessary nor sufficient to cause all cases of ADHD (p. 1336)”. Thus, an important goal in ADHD research is to examine abnormalities in lower-order, more ‘basic’ brain processes as these may contribute to the heterogeneous pattern of behavioral symptoms observed clinically. As described in the previous sections, motor skills are frequently deficient in ADHD and it is possible that basic motor deficits may contribute to higher-order dysfunction. As such, motor functioning in ADHD constitutes an important area of research. ! ! 6! !