The Role of Effortful Control And Cortisol In The Emergence of ADHD, ASD, And Anxiety In Boys

97 Pages·2017·0.75 MB·English

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Theses and Dissertations
2015
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Marissa L. Robinson
University of South Carolina
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Robinson, M. L.(2015). The Role of Effortful Control And Cortisol In The Emergence of ADHD, ASD, And
Anxiety In Boys With FXS. (Doctoral dissertation). Retrieved from https://scholarcommons.sc.edu/etd/
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THE ROLE OF EFFORTFUL CONTROL AND CORTISOL IN THE EMERGENCE OF
ADHD, ASD, AND ANXIETY IN BOYS WITH FXS

by

Marissa L. Robinson

Bachelor of Science
North Greenville University, 2010

Master of Arts
University of South Carolina, 2012

Submitted in Partial Fulfillment of the Requirements

For the Degree of Doctor of Philosophy in

School Psychology

College of Arts and Sciences

University of South Carolina

2015

Accepted by:

Jane E. Roberts, Major Professor

Lindsay M. McCary, Committee Member

Svetlana Shinkareva, Committee Member

Fred Greer, Committee Member

Lacy Ford, Senior Vice Provost and Dean of Graduate Studies
© Copyright by Marissa L. Robinson, 2015
All Rights Reserved
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ABSTRACT
ADHD, ASD, and anxiety are three of the most common co-occurring disorders
in children with FXS leading to increased social, academic, and behavioral difficulties (Bailey,
Raspa, Olmsted, & Holiday, 2008). Early identification and treatment of these co-occurring
mental health disorders is essential to promote optimal outcomes; therefore, the study of early
precursors and underlying mechanisms of these disorders within a developmental framework is
warranted. The current dissertation includes two sequential and related studies investigating
impaired effortful control as a precursor and HPA axis dysfunction (measured through salivary
cortisol) as an underlying mechanism to the emergence of ADHD, ASD, and anxiety in young
boys with FXS. Results indicate that boys with FXS exhibit lower levels of effortful control and
higher levels of cortisol compared to typically developing controls; however, no significant
relationship between effortful control and cortisol was found. Additionally, significantly higher
levels of ASD symptoms were found in the FXS group. Due to significant variability in
individual ADHD, ASD, and anxiety trajectories across FXS and typically developing young
boys, no specific trend in developmental trajectories was found. Impaired effortful control did not
significantly relate to ADHD, ASD, or anxiety symptoms; however, increased cortisol levels
were found to relate to increased anxiety symptoms. Future research is necessary to better
understand the development of these disorders within FXS throughout childhood to assist with
early detection and treatment efforts.

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TABLE OF CONTENTS
ABSTRACT..........................................................................................................................iii
LIST OF TABLES....................................................................................................................v
LIST OF FIGURES..................................................................................................................vi
LIST OF ABBREVIATIONS....................................................................................................vii
CHAPTER 1: INTRODUCTION.................................................................................................1
CHAPTER 2: STUDY 1..........................................................................................................22
2.1 METHODS............................................................................................................22
2.2 RESULTS.............................................................................................................28
CHAPTER 3: STUDY 2..........................................................................................................32
3.1 METHODS............................................................................................................32
3.2 RESULTS.............................................................................................................43
CHAPTER 4: DISCUSSION....................................................................................................63
REFERENCES.......................................................................................................................74
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LIST OF TABLES
Table 1.1 Description of anxiety disorders in childhood ..................................................19
Table 1.2 Labels and definitions of scales comprising effortful control...................................20
Table 2.1 Study 1 descriptives...........................................................................................29
Table 2.2 Linear regression results, Outcome: effortful control.......................................30
Table 3.1 Overview of observation totals by predictor variable.......................................48
Table 3.2 Study 2 descriptives at first observation............................................................49
Table 3.3 Linear model of growth in ADHD symptoms...................................................50
Table 3.4 Linear regression results of cortisol predicting ADHD symptoms...................51
Table 3.5 Linear model of growth in ASD symptoms......................................................52
Table 3.6 Linear regression results of cortisol predicting ASD symptoms.......................53
Table 3.7 Linear model of growth in anxiety symptoms...................................................54
Table 3.8 Linear regression results of cortisol predicting anxiety symptoms...................55
Table 3.9 Descriptives of group comorbidities .................................................................56

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LIST OF FIGURES
Figure 1.1 The neuroconstructivistic approach.................................................................21
Figure 2.1 Group comparisons of mean levels of effortful control and cortisol...............31
Figure 3.1 Individuals trajectories of ADHD symptoms...................................................57
Figure 3.2 Group comparison of ADHD trajectories .......................................................58
Figure 3.3 Individuals trajectories of ASD symptoms......................................................59
Figure 3.4 Group comparison of ASD trajectories ...........................................................60
Figure 3.5 Individuals trajectories of anxiety symptoms..................................................61
Figure 3.6 Group comparison of anxiety trajectories .......................................................62
Figure 4.1 Comparison of prevalence rates among the general population, FXS
populations, and the current FXS sample..........................................................................72
Figure 4.2 Comparison of prevalence rates in preschool-aged children and the current
FXS sample........................................................................................................................73
vi
LIST OF ABBREVIATIONS
ADHD..................................................................Attention-Deficit Hyperactivity Disorder
ASD............................................................................................Autism Spectrum Disorder
FXS.......................................................................................................Fragile X Syndrome
TD.......................................................................................................Typical Development
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CHAPTER 1
INTRODUCTION
Fragile X Syndrome (FXS) is the most common inherited cause of intellectual
disability affecting as many as 1 in 2,500 males (Fernandez-Carvajal et al. 2009;
Hagerman, 2008). An expanded number of CGG trinucleotide repeats at the FMR1 gene
(Xq27.3) on the X chromosome causes FXS. The consequence of expanded CGG repeats
is a reduction of the expression of the fragile X mental retardation protein (FMRP),
leading to atypical brain development (Crawford, Acuna, & Sherman, 2001). The full
mutation of fragile X occurs when the expansions of CGG reach 200 or more while the
FX premutation occurs with 55-199 CGG repeats (Yu et al., 1991). Cognitive impairment
is one of the core features of FXS as IQ scores typically fall in the moderate range of
intellectual disabilities (IQ scores between 45 and 60; e.g. Loesch et al., 2002; Hall et al.,
2008; Hooper et al., 2008). Gender differences exist within the full mutation as females
typically experience less severe impairment compared to males due to the second X
chromosome available to produce the FMRP protein. Diagnoses can be made via pre- or
post-natal genetic testing; however, in the absence of a family history, FXS is not
typically diagnosed in boys until 37 months (Bailey, Raspa, Bishop, & Holiday, 2009).
While intellectual disabilities are almost hallmark in fragile X syndrome, nearly
80% of individuals with FXS have one or more co-occurring condition (Bailey, Raspa,
Olmstead, and Holiday, 2008). Attention-deficit hyperactivity disorder (ADHD; 84%),
autism spectrum disorder (ASD; 46%), and anxiety (70%) are three of the most
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commonly identified comorbid conditions within FXS (Bailey, Raspa, Olmstead, and
Holiday, 2008; Cordeiro, Ballinger, Hagerman, & Hessl, 2011). Individuals with FXS
and other co-occurring conditions tend to have poorer outcomes including greater
behavior problems, more restrictive school placements, lower levels of personal
independence, reduced language skills, and poorer social skills (e.g. Faraone, Biederman,
& Zimmerman, 2005; Handen, Janosky, & McAuliffe, 1997; Bailey et al., 2000; Hatton
et al., 2002; Kau et al, 2004). Additionally, many individuals with FXS experience sub-
threshold symptoms of ADHD, ASD, and anxiety and experience some of these negative
outcomes due to the symptom manifestations (Bailey et al., 2008). For example, more
than 80% of children with FXS have been treated for attention problems, 90% of children
with FXS exhibit one or more symptoms of ASD, and 56-70% of children with FXS
receive treatment for anxiety problems (Bailey et al., 2008; Clifford et al., 2007). Due to
the greater negative outcomes associated with comorbidities in FXS as well as sub-
threshold symptom manifestations, there is a greater need for early identification and
further research on the study of symptom severity to facilitate treatment efforts.
In children without FXS, ADHD typically emerges before the age of 5 with an
average diagnosis age of 7 (CDC, 2010) while ASD typically emerges between the ages
of 2 and 3 years with an average diagnosis age of 4 (Lord et al., 2006; CDC, 2012).
Anxiety disorders typically emerge during middle childhood before the age of 12
(Beesbo, Knappe, & Pine, 2009). While children with FXS exhibit higher rates of these
comorbid disorders, it is not known when comorbid conditions emerge in children with
FXS. In order to better understand the emergence of these disorders, a study of the
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