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Executive functioning is a multidimensional concept encompassing higher-order adaptive abilities, such as judgment, decision-making, self-monitoring, planning, and emotional regulation. Disruption in executive functioning often results in devastating impairments in vitally-important areas of life, such as one's ability to hold employment and maintain social relationships. Executive functions have been associated primarily with the prefrontal cortex. However, the nature and degree of the association between frontal lobe damage and performance on executive functioning tests remains controversial. Research suggests that the association may vary based on the specific location of damage within the prefrontal cortex, as well as the used measure of executive functioning. Few investigations have systematically addressed these variables. The current study employed the lesion method to investigate the relationship between performance on a battery of executive functioning tests and damage to specific regions of the prefrontal cortex. Three groups of participants with lesions in one of the locations of interest [ventromedial prefrontal (VMPC, n = 14), dorsolateral prefrontal (DLPC, n = 14), and non-frontal (n = 18)] were administered the Delis-Kaplan Executive Function System (D-KEFS, 2001), a comprehensive battery of executive functioning tests. Results revealed no statistically-significant differences between group performances on the D-KEFS primary measures. However, a qualitative analysis of the results revealed several meaningful group differences. It appears that some relationship exists between frontal lobe damage, particularly in the DLPC, and decreased performance on several executive functioning tests but further research overcoming the methodological limitations of most existing literature on this topic is needed to clearly resolve this issue.

Executive functions (including attentional shifting/flexibility, working memory, and inhibitory control) are strong predictors of children's early school success (Blair & Razza, 2007; Espy et al., 2004). The current study explored questions related to measurement of executive functions in preschool-aged children. Convergent and predictive validity were assessed for two traditional executive function tasks (the Dimensional Change Card Sort and the Day-Night Stroop), a behavioral executive function task (the Head-Toes-Knees- Shoulders, HTKS), and teacher ratings of child classroom behavior (the Child Behavior Rating Scale, CBRS). All measures were low-to-moderately correlated for the full sample of preschoolers. The CBRS and the HTKS tasks were the most consistent predictors of emergent mathematics, vocabulary, and literacy, controlling for child age and Head Start status; however, all tasks were significantly related to each achievement outcome. Additionally, the convergent and predictive validity of the executive function tasks and teacher ratings were examined by Head Start status. Results show that the tasks were more closely related in non Head Start children. For predictive validity, the most notable difference was for the Day-Night Stroop, which was a strong consistent predictor of academic outcomes for non Head Start children but not for Head Start children. Together, these findings provide insight to the convergent and predictive validity of executive function tasks during early childhood and differences in executive function associated with Head Start status. / Graduation date: 2012

<p>In addition to the adverse effects of high blood pressure (HBP) on cardiovascular disease, HBP is also associated with increased risk of stroke, dementia, and neurocognitive dysfunction. Although aerobic exercise and dietary modifications have been shown to reduce blood pressure, no studies have examined the effects of a combined aerobic exercise and dietary intervention on neurocognition among individuals with HBP, a group at elevated risk for neurocognitive dysfunction. As part of a larger investigation, the ENCORE study, this study examined the effects of dietary modification alone and combined with aerobic exercise on neurocognitive function among individuals with HBP. One hundred twenty five individuals with high normal blood pressure were randomized to an aerobic exercise and dietary modification group (DASH + WM), dietary modification alone (DASH-A), or a usual care control group. Participants completed a battery of neurocognitive tests assessing executive function and vigilance at baseline and again following the four month intervention. Following the intervention, participants in the DASH + WM and DASH-A groups exhibited modest improvements in neurocognitive function relative to controls, and these changes appeared to be mediated by improved cardiovascular fitness and weight loss. A combined aerobic exercise and dietary intervention improves neurocognitive function among individuals with HBP.</p> / Dissertation

Substantial evidence emphasizing the importance of linguistic systems in reading acquisition, as well as emerging literature identifying the contribution of executive function to linguistic-based difficulties, underscores the importance of clarifying the neurocognitive mechanisms affecting reading performance. Research demonstrating the interrelationship between reading and spelling, coupled with neurocognitive theories of spelling, suggests that analysis of children’s spelling attempts may capture more subtle differences in their understanding of how to decode text. This study aimed to determine the utility of applying a spelling error analysis system as a method for differentiating between reading difficulties resulting from executive dysfunction or language deficits in a sample of children at risk for reading failure. The present study examined the relationship between executive function, language, and spelling achievement in a sample of 82 children aged 6-15 years identified as having a reading deficit and/or diagnosed with Attention-Deficit/Hyperactivity Disorder (ADHD). Hierarchical regression analyses indicated language-based skills, particularly word reading, and age significantly predicted the phonemic equivalency of misspellings. Tasks of executive functioning were not found to significantly contribute to performance on phonological spelling; however, analysis of group differences suggest that ADHD and Reading Deficit groups demonstrated unique cognitive profiles, including distinct performances on executive functioning tasks. Exploratory analyses also revealed that ADHD and Reading Deficit groups differed significantly in phonological spelling performance. Results from the current study provide evidence for the presence of two distinct underlying cognitive processes affecting spelling and, in effect, reading. Current findings have implications for the need to further examine characteristic deficits in language and executive functioning affecting children at risk for reading failure. Findings also provide support for the validity of further investigating the potential to infer differential diagnostic categories using a phonological spelling analysis. The use of an analysis of spelling errors as a diagnostic data source holds promise for a better understanding of reading failure and, ultimately, may contribute to more effective intervention practices. / text

Introduction: Idiopathic Parkinson's disease (PD) is a chronic and progressive neurodegenerative disorder that is characterised by motor symptoms. However, there is increasing awareness that a range of neuropsychiatric and cognitive problems also accompanys PD. The objective of this thesis was to examine the profile of neuropsychiatric and cognitive problems for patients with PD without dementia. Parkinson's disease patients who could be identified at the time of this study were invited to participate. Each patient was individually matched to a healthy control in terms of age, premorbid intelligence, and years of education. Results: Neuropsychiatric symptoms were common for this patient group, over 40% self reported symptoms consistent with depression, 40% with physical fatigue, 38% with mental fatigue, 38% with apathy and 32% with sleep problems. More than 77% of patients with PD reported symptoms associated with at least one problem and over 46% with 3 or more problems. Increased symptoms consistent with depression and anxiety and the presence of hallucinations also predicted poorer quality of life after controlling for motor symptoms. However, the of level agreement between patient report and that of a person who know them well was low: 40.9% for apathy, 28% for hallucinations, 39% for depression, 25% for sleep problems and only 7.7% agreement for the presence of anxiety. To obtain an accurate profile of cognitive impairments patients were assessed on measures of higher order language ability and a broad range of commonly used cognitive tests. Overall, PD patients were impaired on aspects of higher-order language. However, results indicated that these deficits were not a primary effect of PD, but could be explained in terms of deficits in speed of information processing associated with the disease. Compared to healthy controls, PD patients also showed deficits on measures of executive function, working memory, problem solving, and visuospatial skills. However, they were unimpaired on measures of planning, attention and memory/learning. Deficits in problem solving were only evident for tasks with a high visuospatial content and were no longer significant when visuospatial skills were controlled for. Further investigation indicated that planning in PD patients was not impaired in general and was dependent on the sensitivity of tests used. To further examine cognitive deficits, patients were divided into groups according to their cognitive performance. Three sub-groups of patients were identified that formed a continuum of cognitive impairment from none/mild to severe. Compared to controls, one subgroup showed no or minimal impairment (PD-NCI), a second group showed a more variable pattern of severe and mild impairments (PD-UCI), and a third group had evidence of severe impairment across most of the cognitive domains tested. This latter group was labelled PD-Mild Cognitive Impairment (PD-MCI). The PD-UCI and PD-MCI groups were also significantly different from their controls with respect to their ability to carry out functional activities of everyday living. The PD-MCI group had evidence of global cognitive decline, possibly reflecting a stage of pre-clinical dementia. The severity of cognitive deficits was not associated with other clinical and demographic characteristics such as motor impairments, age or disease duration. These results were confirmed when patients were retested one year later. Conclusions: Comorbid neuropsychiatric and cognitive problems are common for patients with PD prior to any overt signs of dementia. However, PD patients are heterogeneous with regard to their presentation and different subgroups of patients are identifiable based on cognitive performance. This information has both theoretical and clinical relevance.

The purpose of this study was to examine the contribution of different aspects of executive function (EF) and social understanding to emotion regulation (ER), and the influence of these aspects of self-regulation on temper tantrums. A model of self-regulation is presented in which ER, EF, and social understanding contribute to self-regulatory competence. General cognitive (i.e., language) and emotional (i.e., temperamental emotional reactivity) measures are included to increase the specificity of the relation between ER and other aspects of self-regulation. ER, EF, and social understanding were also examined in relation to temper tantrums. One hundred twenty seven preschool children and their parents completed batteries of ER, EF, and social understanding, as well as measures of verbal ability, temperament, and temper tantrums. This study extends previous research by including multitrait, multimethod assessment of EF, ER, and social understanding, and controlling for verbal ability and emotional reactivity. Exploration of temper tantrums offers a unique illustration of the manner in which aspects of self-regulation contribute to everyday displays of strong emotion in preschoolers. Overall, the results of this investigation provided evidence that aspects of EF and social understanding are related to ER and that these aspects of self-regulation are also related to temper tantrums. More specifically, this study makes three main contributions to understanding children’s ER. First, there was evidence that EF and social understanding were related to ER even after individual differences in emotional reactivity and verbal ability had been removed. Affective social understanding, but not cognitive social understanding, was a useful predictor in the regression model. Among the EF variables, there was evidence that individual differences in both response and delay inhibition contributed significantly to ER. This finding replicates and extends Carlson and Wang’s (2007) findings of partial correlation (controlling for verbal ability) between inhibitory control and ER. Second, individual differences in both delay inhibition and ER contributed to the prediction of temper tantrums, even after controlling for emotional reactivity. Social understanding variables were not included in this analysis because correlations between social understanding and temper tantrums were low. Finally, mediation analysis provided evidence that ER significantly buffers the effect of emotional reactivity on temper tantrums. That is, the effect of emotional reactivity on temper tantrums was significantly reduced by ER. This effect remained even after controlling for age. These findings suggest that inhibitory control and affective social understanding make unique contributions to understanding ER and that temper tantrums are related to inhibitory control and ER.

The experiments in this thesis explored the development of executive function in 5- to 11-year-old children. Developmentally-appropriate versions of the task-switching paradigm, go/no-go task and self-ordered pointing test were used to measure shifting, inhibition and working memory respectively. These executive skills were examined independently and within-task experimental manipulations were used to explore both the executive and non-executive processes that influenced children’s performance. These allowed the investigation of not only when, but also how executive function develops. It was found that shifting development, as measured by the task-switching paradigm was highly influenced by the specific tasks switched between and the conflict created by the overlap of the tasks, as well as by previous task experience. Working memory for pictures was also influenced by previous experience and task difficulty, however the predicted relationship between memory for nameable objects and language ability was not found. Inhibition on the go/no-go paradigm appeared to be driven by an improvement in the efficiency of response inhibition enabling older children to inhibit a response at an earlier stage during the movement. Shifting, inhibition and working memory all showed developmental improvements during mid-childhood, demonstrating the protracted development of executive function. Shifting and working memory showed a similar pattern of development whereas inhibition reached a stable level of performance at an earlier age. There were no correlations between the three executive skills studied in this thesis, supporting the fractionation of executive function.

Background: Patients with non-penetrating traumatic brain injuries (TBI) are at high risk for damage to ventral prefrontal brain regions, due to the brain’s acceleration into the bony ridges of the anterior portions of the skull. Current neuropsychological assessments of these patients focus mainly on the assessment of so-called “executive functions,” which are associated with dorsolateral prefrontal regions. Ventral prefrontal pathology is more likely to disrupt social and emotional functions, but assessments of these abilities using objective measurements that require patients to demonstrate their competence are rare. Mounting evidence suggests that chronic social and emotional deficits are common in TBI, and that these difficulties result in significant functional impairments post-injury, making clear the need to develop and use objective assessment tools during clinical neuropsychological assessments. Methods: In the current project, the Global Interpersonal Skills Test (GIST), a questionnaire measure of social skills with both a self-rated and an informant-rated version, was developed, along with three novel or adapted performance-based measures of social and emotional functioning. The first novel measure was the Assessments of Social Context (ASC), a video-based task examining comprehension of social context using non-verbal cues, including the identification of emotions, intensions and positive or negative attitudes of one person towards another. The second task was the Awareness of Interoception Test (AIT), a heartbeat detection paradigm adapted from previous literature that measures participants’ sensitivity to their cardiac function, which is implicated in basic emotional functioning. The third task was the Social Interpretations Task (SIT), an animation-based task adapted from previous literature examining participants’ ability to apply a social interpretation to stimuli that are not inherently social in nature. All novel tasks were developed and piloted with healthy undergraduates. A group of patients with moderate to severe TBI (N = 16), and a group of non-brain damaged controls (N = 16) underwent neuropsychological testing. Standard neuropsychological measures including the Wechsler Test of Adult Reading, Digit Span and Digit Symbol Coding from the Wechsler Adult Intelligence Scale, phonemic (FAS) and semantic fluency (Animals) from the Verbal Fluency Test, and the Trail Making Test, as well as the novel measures to both patients with TBI and controls were administered. The following predictions were made: vi 1) The novel performance-based measures of social abilities would be more sensitive to the presence of moderate and severe TBI than the standard neuropsychological measures of cognition; 2) On the informant version of the GIST, but not the self-report version, patients would have scores than controls; 3) Patients’ performance on the ASC would be less accurate than controls’, and this difference would be associated with real-world social skills, measured by the informant-version of the GIST; 4) Patients’ AIT performance would be less accurate than controls’, and this would be related to their self-rated emotional changes; 5) Patients’ SIT performance would be less accurate than controls’, and this difference would be associated with real-world social skills, again measured by the informant-version of the GIST. Findings: Findings were consistent with these hypotheses: 1) A statistically significant logistic regression revealed that a Social composite variable comprising the ASC, AIT and SIT was more sensitive to the presence of TBI (β = 9.59, p < .05) than a Cognitive composite variable comprising Digit Symbol Coding, Trails B completion time, and Phonemic Fluency (β = 0.006, p = .466). 2) A multivariate analysis of variance (MANOVA) revealed that informants of patients gave lower GIST scores to patients than the informants of controls (F(1,28) = 22.2, p < 0.0001), whereas there were no differences between groups on the self-rated version of the GIST (F(1,28) = .35, p = .56); 3) Patients’ ASC performance was significantly poorer than controls’ on a MANOVA (F(1,31) = 21.7, p < .0001), and ASC total scores were significantly correlated with GIST informant scores, using Spearman’s rank-order correlations (ρ(31) = .624, p < .0001). 4) Patients’ AIT performance was significantly poorer than controls’ using an independent samples t test (t(13) = 1.43, p < 0.005), and qualitative investigation of subjective reports of emotional change among patients suggested a potential relationship between emotional changes and AIT performance. vii 5) Patients’ SIT performance was significantly poorer than controls on an independent samples t test (t(30) = -2.12, p < 0.05), and SIT scores were significantly correlated with GIST informant scores, using Spearman’s rank-order correlations (ρ(31) = .460, p < .0001). Interpretation: This research represents a preliminary step in the development of clinically useful measures of social and emotional difficulties following TBI. Given the small sample size of the patient group, and the presence of co-morbid difficulties among some of the participants in this research, further testing of these measures in larger, more homogeneous samples would strengthen the current results, as would using a comparison group of people with milder TBI, rather than neuro-typical controls. The complexity of social behaviour requires that the current measures be further validated against other real-world assessments of social ability, and that assessments of other aspects of social behaviour be conducted. Nonetheless, the measures described here are a promising start to supplementing the neuropsychological toolkit in an area that requires further development at the present time.

Background: Patients with non-penetrating traumatic brain injuries (TBI) are at high risk for damage to ventral prefrontal brain regions, due to the brain’s acceleration into the bony ridges of the anterior portions of the skull. Current neuropsychological assessments of these patients focus mainly on the assessment of so-called “executive functions,” which are associated with dorsolateral prefrontal regions. Ventral prefrontal pathology is more likely to disrupt social and emotional functions, but assessments of these abilities using objective measurements that require patients to demonstrate their competence are rare. Mounting evidence suggests that chronic social and emotional deficits are common in TBI, and that these difficulties result in significant functional impairments post-injury, making clear the need to develop and use objective assessment tools during clinical neuropsychological assessments. Methods: In the current project, the Global Interpersonal Skills Test (GIST), a questionnaire measure of social skills with both a self-rated and an informant-rated version, was developed, along with three novel or adapted performance-based measures of social and emotional functioning. The first novel measure was the Assessments of Social Context (ASC), a video-based task examining comprehension of social context using non-verbal cues, including the identification of emotions, intensions and positive or negative attitudes of one person towards another. The second task was the Awareness of Interoception Test (AIT), a heartbeat detection paradigm adapted from previous literature that measures participants’ sensitivity to their cardiac function, which is implicated in basic emotional functioning. The third task was the Social Interpretations Task (SIT), an animation-based task adapted from previous literature examining participants’ ability to apply a social interpretation to stimuli that are not inherently social in nature. All novel tasks were developed and piloted with healthy undergraduates. A group of patients with moderate to severe TBI (N = 16), and a group of non-brain damaged controls (N = 16) underwent neuropsychological testing. Standard neuropsychological measures including the Wechsler Test of Adult Reading, Digit Span and Digit Symbol Coding from the Wechsler Adult Intelligence Scale, phonemic (FAS) and semantic fluency (Animals) from the Verbal Fluency Test, and the Trail Making Test, as well as the novel measures to both patients with TBI and controls were administered. The following predictions were made: vi 1) The novel performance-based measures of social abilities would be more sensitive to the presence of moderate and severe TBI than the standard neuropsychological measures of cognition; 2) On the informant version of the GIST, but not the self-report version, patients would have scores than controls; 3) Patients’ performance on the ASC would be less accurate than controls’, and this difference would be associated with real-world social skills, measured by the informant-version of the GIST; 4) Patients’ AIT performance would be less accurate than controls’, and this would be related to their self-rated emotional changes; 5) Patients’ SIT performance would be less accurate than controls’, and this difference would be associated with real-world social skills, again measured by the informant-version of the GIST. Findings: Findings were consistent with these hypotheses: 1) A statistically significant logistic regression revealed that a Social composite variable comprising the ASC, AIT and SIT was more sensitive to the presence of TBI (β = 9.59, p < .05) than a Cognitive composite variable comprising Digit Symbol Coding, Trails B completion time, and Phonemic Fluency (β = 0.006, p = .466). 2) A multivariate analysis of variance (MANOVA) revealed that informants of patients gave lower GIST scores to patients than the informants of controls (F(1,28) = 22.2, p < 0.0001), whereas there were no differences between groups on the self-rated version of the GIST (F(1,28) = .35, p = .56); 3) Patients’ ASC performance was significantly poorer than controls’ on a MANOVA (F(1,31) = 21.7, p < .0001), and ASC total scores were significantly correlated with GIST informant scores, using Spearman’s rank-order correlations (ρ(31) = .624, p < .0001). 4) Patients’ AIT performance was significantly poorer than controls’ using an independent samples t test (t(13) = 1.43, p < 0.005), and qualitative investigation of subjective reports of emotional change among patients suggested a potential relationship between emotional changes and AIT performance. vii 5) Patients’ SIT performance was significantly poorer than controls on an independent samples t test (t(30) = -2.12, p < 0.05), and SIT scores were significantly correlated with GIST informant scores, using Spearman’s rank-order correlations (ρ(31) = .460, p < .0001). Interpretation: This research represents a preliminary step in the development of clinically useful measures of social and emotional difficulties following TBI. Given the small sample size of the patient group, and the presence of co-morbid difficulties among some of the participants in this research, further testing of these measures in larger, more homogeneous samples would strengthen the current results, as would using a comparison group of people with milder TBI, rather than neuro-typical controls. The complexity of social behaviour requires that the current measures be further validated against other real-world assessments of social ability, and that assessments of other aspects of social behaviour be conducted. Nonetheless, the measures described here are a promising start to supplementing the neuropsychological toolkit in an area that requires further development at the present time.