The evidence suggesting Attention-Deficit/Hyperactivity Disorder (ADHD) has neurodevelopmental roots with specific impairment in executive functioning continues to grow. However, no known study to date has explored the relationship between adult males with a diagnosis of ADHD and performance on a measure of executive functioning, the Delis-Kaplan Executive Function System (DKEFS). The current investigation attempted to explore (1) whether adult males with ADHD show an overall pattern of executive dysfunction as measured by the DKEFS, (2) potential group differences on both level-of-performance and process-oriented measure scores, and (3) the clinical utility of the DKEFS in diagnosing ADHD in adult males. A sample of 37 adults with ADHD was compared to a community sample of equal size. Multivariate statistical analysis yielded significant group differences despite intellectual advantage by the study group. In addition, analysis of individual measures revealed patterns which were not initially predicted based upon current theories of ADHD. Overall, however, no clinically significant impairments emerged, as defined by scores at least one standard deviation below the mean. These findings and potential clinical implications are discussed with recommendations for future research.

Introduction: Executive functions (EFs) are a set of inter-related neurocognitive abilities, recruited for top-down, conscious control of thoughts, actions and emotions. EFs develop rapidly during the preschool period (age 3 to 6 years), which is the same time, during which the symptoms of Attention Deficit/Hyperactivity Disorder (ADHD), namely hyperactivity, impulsivity, and inattention, become evident. Furthermore, hyperactivity, inattention, and the EFs contribute to academic performance once children begin formal schooling. To clarify the interplay of these processes, this dissertation conducted 3 studies that used a longitudinal design (4 time-points) to investigate the development of EFs from age 3 to 6 years, the relations between EFs and hyperactivity across this same period of time, and their relative contributions to inattention and academic performance at 6 years of age. Study One: Children’s performance on EF tasks was examined across 4 time points, beginning at 36-48 months of age. Results indicated significant between-child variability for all EF component processes at 3 years of age, significant growth over time, and preliminary support for the theory that, among EFs, working memory may develop first. Furthermore, EF performance at 3 years of age made significant contributions to performance on complex tasks of problem solving and planning at 6 years of age. Study Two: The aim of study two was to evaluate the relations between EF, hyperactivity, and inattention. Results indicated significant between-child variability in EF task performance, with a decrease in variability from age 3 to 4.5 years. Hyperactivity at age 3 years reliably predicted hyperactivity at 6 years of age for females, who also had lower hyperactivity scores. In contrast, for males, child EF performance and parent-report of EF at age 3 years were the best predictors of hyperactivity at 6 years of age. Study Three: The aim of study three was to expand upon the relations between EF, hyperactivity, and inattention by evaluating their relative contributions to academic performance. There were limited relations between academic performance, hyperactivity, and inattention. However, EF performance at 3 years of age predicted age 6 reading and math, whereas parent-report EF only predicted reading. Furthermore, hyperactivity at 4.5 years of age moderated the relation between age 3 performance EF and age 6 academic performance, with this relation becoming stronger as hyperactivity increased. Conclusion: Together, these studies make several notable contributions to the field: (a) that initial EF abilities at 3 years of age are highly variable between children, but improve consistently over time, (b) that the relations between hyperactivity and EF appear to be different for males and females (or higher/lower levels of hyperactivity), and (c) that even in a community sample, hyperactivity moderates the EF-academic performance relation. These findings contribute to the early identification of hyperactivity and interindividual differences in EF abilities, in very young pre-schoolers, who may go on to have more difficulty in a formal schooling setting. / Graduate / 2023-08-09

An evaluation of executive functioning is a critical component of a comprehensive assessment of higher cerebral functioning. The Tinker Toy Test (TTT) was introduced in 1982. This test allows an individual to demonstrate the extent of their executive capacities by permitting them to initiate, plan, and structure a potentially complex activity and carry it out independently in an unstructured fashion and administration is simple. This is a departure from more complex and structured tests of executive function. There is a dearth of research on the TTT and this study seeks to examine some of the psychometric properties of this instrument; i.e., working time minimum, gender effects, convergent and divergent validity, and potential intellectual correlates. Participants included 10 male and 30 female student volunteers from a large university in Central Florida. Participants had no history of neurologic disease/trauma or conditions that would affect motor functioning of the upper extremities. Participants completed a demographic questionnaire, the WASI-II, and the TTT. A two-way mixed-design ANOVA examining TTT scores as a function of work time and gender revealed a non-significant gender main effect, F(1, 21) = .09, p = .767. The work time main effect was not significant, , F(1, 21) = .324, p = .575. A significant work time x gender interaction was observed, F(1, 21) = 4.983, p = .037. Convergent validity was assessed by comparing the TTT scores with the Matrix Reasoning subtest, r(38) = .32, p = .044, and the Similarities, r(38) = .34, p = .03, subtest on the WASI-II. Divergent validity was assessed by comparing TTT scores to the Block Design subtest of the WASI-II, r(38) = .245, p = .127. No significant correlation was found between intelligence and TTT (VCI, r(38) = -.16, p = .335; PRI, r(38) = .15, p = .344; and FSIQ, r(38) = -.02, p = .928). The data supports the continued use of the 5-minute working time minimum presented by Lezak, as this temporal index was a more accurate representation of executive functioning. This study demonstrated no association between TTT scores and intellectual functioning. The findings of this study support the validity of this underutilized test of executive functioning and its inclusion in neuropsychological test batteries.

As the popularity of video games increases, a growing literature has begun to examine the association of video game play with cognitive processes. An advantage in cognitive control ability for video game players (VGPs) compared to nongamers (nVGPs) has been suggested by a number of recent studies. Miyake et al. (2000) identify three separable components of cognitive control: ability to shift mental set, updating and monitoring of working memory, and ability to inhibit automatic responses. In three sets of experiments, we investigated claims of a benefit in cognitive control for VGPs compared to nVGPs. Chapter 2 used two task switching paradigms to examine the ability to shift mental set, finding no difference in cognitive control between VGPs and nVGPs when baseline differences in response speed were accounted for. In Chapter 3, a series of nback experiments to investigate working memory demonstrated that VGPs display an advantage in spatial processing, but not in cognitive control. Chapter 4 assessed group differences using three measures of inhibitory control: flanker, Stroop, and go no-go tasks. The results of these experiments suggest that VGPs may rely more on automaticitybased response strategies than do nVGPs, but no group differences in cognitive control were evident. Overall, the results of this dissertation dispute a growing literature that assumes a cognitive control benefit for VGPs compared to nVGPs. Although VGPs reliably show faster performance on a range of tasks used to assess cognitive control (e.g., task switching paradigms), when examined with careful methods, these observed differences in performance are not attributable to differences in cognitive control ability. / Dissertation / Doctor of Philosophy (PhD) / Many people enjoy playing video games, and it is important to understand whether playing these games is associated with differences in the way we think, or our ability to complete tasks. Previous studies have claimed that playing video games is associated with increased control over our ability to selectively respond to our environment. This dissertation uses a series of experiments to compare the cognitive control ability of video game players (VGPs), and people who do not play video games (nVGPs). We tested their ability to switch between different tasks, to hold items in memory, and to withhold responses. Results of these experiments suggest that although VGPs may generally respond faster and process spatial information better than nVGPs, there are no differences in cognitive control between VGPs and nVGPs.

Concussions impact the cognitive abilities and emotional wellbeing of adolescents. More specifically, adolescents exhibit signs of executive dysfunction and depressive symptoms following concussion. Evidence suggests a link between cognitive performance and depressive symptoms in concussed populations; however, concussion research has focused mostly on cognitive deficits and emotional dysregulation in singularity, rather than as an integrated system. Therefore, the purpose of this thesis is to explore the clinical and biological relationship between depressive symptoms and executive dysfunction following mild traumatic brain injury (mTBI) or concussion in pediatric populations. Chapter 1 provides an overview of the literature surrounding children and youth with concussive injury as it pertains to executive dysfunction and depressive symptoms. Chapter 2 describes the clinical nature of the relationship between depressive symptoms and executive dysfunction. The results demonstrate that individuals with elevated depressive symptoms had comparable performance to individuals with normal levels of depressive symptoms on executive function scores. This included their performance on an inhibitory control task in which emotional distractors were presented. Regardless of levels of depressive symptoms, adolescents with concussive injury displayed impaired executive functioning compared to normative data, which emphasizes the importance of evaluating executive function following concussion. Chapter 3 involves the use of functional brain imaging to explore the physiological differences between adolescents with average and elevated depressive symptoms on emotion-mediated inhibitory control processes. The group as whole did not display activity in the frontostriatal regions that are associated with inhibitory control, which suggests a potential impairment in this network. Adolescents with elevated depressive symptoms displayed fewer areas of activity compared to adolescents with average levels of depressive symptoms. As a number of individuals (particularly those with elevated depressive symptoms) were injured in the occipital region of the skull, the coup-contrecoup impact may have resulted in frontal lobe injury. Faces were used to evoke emotional processing throughout the inhibitory control task. The results revealed that adolescents with elevated depressive symptoms were more likely to engage in brain regions subserving evaluative processing of social interactions. This might suggest that depressive symptoms display differences in physiology when emotional stimuli are present. These findings provide insight into the role the environment plays in contributing to the cognitive demands placed on adolescents recovering from concussion. Chapter 4 reviews the key messages derived from these results and describes their clinical relevance. This exploration may lead to a more holistic understanding of concussion and a better approach to injury management, particularly for adolescents who express higher levels of depressive symptoms following concussion. / Thesis / Master of Science (MSc)

As motor learning in individuals with intellectual disabilities (ID) has been poorly elucidated, this study aimed to apply an acute aerobic exercise (AE), well-known intervention favorable to motor learning in typically developing individuals, to assist people with ID in motor learning, and examine its underlying mechanisms via EF and EEG assessments. 17 adults with ID (11 males, aged 31.41 ± 9.7, & mental aged 7.69 ± 3.06) participated in this within-group counterbalanced study. They participated in 2 interventions, a vigorous treadmill walking (AE) or seated rest (CON) condition, with having a month of wash-out period in between interventions. The pre-test, post-test, 24-hour retention test, and 7-day retention test was administered, and each testing phase administered a golf putt performance under both original (i.e., with guideline) and transfer putt tasks (i.e., without guideline), EF (i.e., Knock and Tap test, forward and backward Digit span test, forward and backward Corsi block test), and resting EEG assessment. Golf putting accuracy in post-test was not significantly different from the pre-test; however, the putt accuracy under the transfer putt task indicated an interaction effect at 24-hour retention test phase compared to pre-test, F(1, 32) = 5.26, p = .03, ηp2 = .14, and paired t-test indicated a near significant improvement in putt accuracy in AE (p = .07), but not in CON condition (p = .23). The pre-test and 7-day retention phases did not indicate a significant effect on golf putt skill. As EF variables and resting EEG temporal alpha asymmetry (TAA) remained unchanged throughout the procedure, underlying mechanisms of change in putt skill need to be further investigated. This study revealed a trend that the AE positively influenced golf putt accuracy and offline motor memory consolidation at 24-hour retention phase, but the effects were not statistically significant. Given that the study procedure did not include practice blocks, the observed positive impact of AE on golf putt accuracy is promising; thus, a future study is recommended to further verify the benefit of AE on motor learning in individuals with ID, as well as with rigorous EF and EEG measures to elucidate possible underlying mechanisms of AE-dependent improvement in motor skill.

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