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<p>This thesis presents research documenting the effectiveness of computer-assisted cognitive remediation for patients with mood disorders. The first chapter provides an overview of cognitive impairment in patients with bipolar disorder (BD) and major depressive disorder (MDD), and a concise review of cognitive remediation in patients with schizophrenia, where the efficacy of these interventions has been reasonably well studied. The results of an analysis comparing neuropsychological test performance in patients with BD, MDD, and healthy controls is presented in Chapter 2, where we show a similar degree of deficit in both patient groups on processing speed, working memory, and mental flexibility tasks, and a greater degree of deficit in patients with BD on delayed recall and verbal fluency tasks. In Chapter 3 we present the results of our primary analysis examining the effectiveness of CACR for patients with BD and MDD; we show significant improvement on neuropsychological tests of working memory and delayed memory following remediation, and positive associations between improvement in neuropsychological test performance, and improvement in subjectively-rated cognitive and psychosocial functioning. Finally, in Chapter 4 we present functional neuroimaging evidence that shows increased activation following cognitive remediation in frontal control regions supporting working memory and in the right hippocampus supporting recollection memory. Although behavioural performance on the corresponding tasks was stable, the observation of increased activation in frontal and medial temporal brain regions following remediation is in line with our finding of improvement on neuropsychological tests of working memory and delayed recall post-training. Taken together, the results presented in this thesis provide convergent behavioural and neural evidence to demonstrate the efficacy of computer-assisted cognitive remediation for patients with mood disorders. These novel findings contribute to a growing body of literature that shows cognitive remediation to be an effective cognitive management strategy across a range of psychiatric and neurological disorders.</p> / Doctor of Philosophy (PhD)

Executive functioning (EF) problems may serve as vulnerability or maintenance factors for Binge-Eating Disorder (BED). However, it is unclear if EF problems observed in BED are related to overweight status or BED status. The current study extends this literature by examining EF in overweight-BED (n=32), normal-weight BED (n=23), overweight healthy controls (n=48), and normal-weight healthy controls (n=48). Participants were administered an EF battery which utilized tests from the National Institutes of Health (NIH) toolkit and Delis-Kaplan Executive Function System (D-KEFS). After controlling for years of education and minority status, overweight individuals with and without BED performed more poorly than normal-weight individuals with and without BED on a task of cognitive flexibility (p &lt; 0.01) requiring generativity and speed and on psychomotor performance tasks (p &lt; 0.01). Normal-weight and overweight BED performed worse on working memory tasks compared to normal-weight healthy controls (p = 0.04). Unexpectedly, normal-weight BED individuals out-performed all other groups on an inhibitory control task (ps &lt; 0.01). No significant differences were found between the four groups on tasks of planning. Our findings support a link between poorer working memory performance and BED status. Additionally, overweight status is associated with poorer psychomotor performance and cognitive inflexibility. Replication of the finding that normal-weight BED is associated with enhanced inhibitory control is needed. / Psychology

It is now well established that children with sickle cell disease (SCD) demonstrate cognitive deficits even in the absence of clinical stroke, but studies in children who have not experienced a stroke or other neurological event are lacking. Systemic processes that occur in SCD, like chronic inflammation and hypoxia, have been associated with hippocampal damage and episodic memory deficits in a range of clinical populations and animal models. However, studies examining episodic memory performance in children with SCD and in relation to systemic processes are largely absent. The present study addressed these gaps in young children with SCD (Mage = 7.37 years, SD = 1.51) who had not experienced a clinical stroke. Participants (N = 31) completed various memory measures as part of a larger neuropsychological protocol and participated in routine clinical blood draws. Latent class analysis (LCA) was used to empirically define SCD groups based on measures of specific visual memory processes, and results revealed two distinct visual memory groups, characterized by (1) visual memory deficits, specifically in delayed recognition abilities, and (2) intact visual memory. Follow-up analyses revealed that the two classes did not significantly differ on verbal memory performance. The relation between memory processes and both biomarkers of inflammation and adaptive functioning also were examined with variable-centered analyses. Results showed only one significant relation between C-reactive protein (CRP) and a measure of verbal delayed recognition. In sum, young children with SCD demonstrate variable episodic memory performance, with most notable deficits in visual delayed recognition. Higher levels of CRP, a biomarker of inflammation, were associated with poorer verbal delayed recognition. The results indicate that young children with SCD experience deficits in memory, even in the absence of a neurological event, and specific memory processes should be assessed in these children to guide targeted interventions. / Psychology

While the neural underpinnings of concrete semantic knowledge have been studied extensively, abstract conceptual knowledge remains enigmatic. In the first experiment, participants underwent a functional MRI scan while thinking deeply about abstract and concrete words. A functional connectivity analysis revealed a cortical network, including portions of the left temporal parietal cortex (TPC), that showed coordinated activity specific to abstract word processing. Alternatively, concrete words led to cooperation of a network in the inferior, middle and polar temporal lobes. In a second experiment, participants with focal lesions in the left TPC, as well as matched control participants, were tested on a spoken-to-written word matching task, in which they were asked to select either an abstract or concrete word, from an array of words that were related or unrelated to the target. The results revealed an interaction between concreteness and relatedness. Participants with lesions did not have an overall deficit for abstract words, relative to concrete words, in this task. However, their accuracy was significantly lower for abstract words in related arrays, compared to words in unrelated arrays. These results confirm that the TPC plays an important role in abstract concept representation, and that it is part of a larger network of functionally cooperative regions needed for abstract word processing. These results also provide converging evidence that abstract concepts rely on neural networks that are independent from those involved in concrete concepts, and have important implications for existing accounts of the neural representation of semantic memory. / Psychology

Cannabis use is becoming increasingly prevalent in Canada and the United States, where legality and public perception have recently shifted to be more permissive of recreational use. Despite established negative health consequences associated with persistent use, there remains considerable debate in the scientific community surrounding the potentially harmful effects of cannabis use on human cognition. Evidence exists that heavy cannabis use predicts diminished performance within several neurocognitive domains and also predicts greater risk of having ADHD. Further evidence suggests that earlier age of first cannabis use strengthens these associations, however the findings in these literatures are mixed and in need of further delineation. This thesis sought to examine continuous associations among current cannabis use severity, age of first use, neuropsychological performance, and ADHD symptomatology. Two studies using large samples of community adults were conducted. Study 1 analyzed data from the Human Connectome Project, and examined performance on a battery of neuropsychological measures among young adults, and found recent use to be the strongest predictor of differences in episodic memory and processing speed, and CUD predicted lower fluid intelligence. Lifetime exposure to cannabis was not associated with any outcome measures. Study 2 examined similar associations in a sample of adults representative of the Hamilton community, and also included self-reported symptoms of ADHD. Study 2 found current cannabis use severity to be predictive of more impulsive reward preferences, and also of both hyperactive-impulsive and inattentive symptoms of ADHD. Both studies found a lack of support for the role of age of first cannabis use in differential cognitive performance, and also failed to find associations between cannabis involvement and several cognitive domains such as working memory, behavioural inhibition, executive function, and psychomotor dexterity. These findings challenge some of the current literature, and highlight the necessity of further investigation to better understand interrelationships among cannabis use, cognition, and ADHD. / Thesis / Master of Science (MSc) / It is unclear to what extent cannabis use effects mental functions such as memory, attention, and intelligence. The goal of this research was to investigate how recent and early-life cannabis use is related to these cognitive functions and real-life problems with attention and impulse control as seen in ADHD. Two studies were performed to investigate these relationships, and together found recent cannabis use rather than lifetime use to be predictive of performance on select cognitive abilities and ADHD symptoms. Age of first cannabis use and lifetime use were not associated with differences in cognition, suggesting that cannabis use in adolescence may not necessarily cause lasting detrimental changes. Rather, people who have symptoms of ADHD may be more likely to use cannabis earlier and in more problematic ways.

Objectives: The first objective of this research was to examine whether symptom dimensions in obsessive-compulsive disorder (OCD) are associated with unique neuropsychological performance profiles. The second objective of this research was to further understand the strengths and weaknesses of two models of symptom dimensions in OCD from a quantitative perspective—conventional subtyping by overt symptom, and the core dimensions model. Finally, the third objective of this research was to investigate the efficacy and treatment acceptability of a cognitive remediation program targeting neurocognitive deficits associated with OCD. Methods: Study 1 reviewed critically studies describing the assessment of differences in neuropsychological functioning between symptom dimensions of OCD, the results of which informed succeeding studies examining: i) the characterization of symptom dimensions in OCD and; ii) the remediation of neuropsychological domains commonly affected in OCD. Accordingly, study 2 compared the suitability of two common statistical approaches, factor analysis and cluster analysis, commonly used in the existing literature to define symptom dimensions based on responses collected from the industry-standard symptom questionnaire, the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), in characterizing symptom dimensions in OCD. Neuropsychological task data were then used to examine the validity of an alternative model of symptom dimensions in OCD (Study 3). Finally, we conducted a feasibility study (Study 4) examining the use of an established cognitive remediation protocol, Goal Management Training (GMT), to target the deficits in neurocognitive function identified in the preceding studies. Results: Much of the existing literature on neuropsychological task performance differences between symptom dimensions of OCD is limited by methodological issues, primarily those concerning methods for defining symptom dimensions. Here, a comparison of the two most common methods for defining dimensions revealed that neither cluster analysis nor factor analysis produced conceptually meaningful subgroups. By exemplifying differences in neuropsychological task performance between those with harm avoidance and those with incompleteness symptoms, however, concrete evidence was provided to support the core dimensions model of OCD. Pilot data point towards the feasibility and efficacy of GMT as a cognitive remediation program for OCD. Conclusions: Pursuing the definition of meaningful, distinct symptom dimensions of OCD is not recommended with the combination of current statistical practices and symptom measures. The early evidence presented here shows promise for the validity of the core dimensions model. Preliminary evidence suggests that the neuropsychological impairments observed in this population, although subtle, may be effectively addressed using Goal Management Training. / Thesis / Doctor of Philosophy (PhD)

Within the field of psychology, hostility has historically been a heavily researched affective construct. The purpose of this experiment was to test hypotheses derived from a neuropsychological model of hostility utilizing two common research paradigms from the extant literatures on hostility's cognitive and physiological correlates. This was accomplished by testing an integral component of a previously proposed neuropsychological model of hostility (Herridge & Harrison, 1994). The purpose of the model was to aid in understanding the chronicity and pervasiveness of a hostile disposition. The model describes a system where physiological arousal level is mediated by systems which also mediate accuracy of an individual's interpretation of affective cues. It was at this level (physiological arousal and perception) that the experimental test was developed. It was predicted that hostile men would show different levels of perceptual accuracy than non-hostile men in both a cold pressor (CP) and no CP condition when tachistoscopically presented with three categories of affective facial configurations (happy, angry, and neutral) in either their left (LVF) or right visual field (RVF). In this sample of college men (N = 56), a four-factor, repeated measures, analysis of variance (ANOVA) produced a significant three-way interaction which indicated that hostile subjects were less accurate than non-hostile subjects in the assessment of happy, angry, and neutral faces in their LVF. However, they were more accurate than subjects classified as non-hostile in the assessment of happy and angry facial configurations in their RVF. Subjects were classified as hostile and non-hostile using joint criteria; the Cook-Medley hostility scale (Ho) and cardiovascular reactivity levels to the arousing stimulus, a CP task. Additionally, a non-significant trend was noted where nonhostile subjects in a no CP state showed more accuracy in the assessment of faces presented to them in their LVF than all other group and CP levels. However, they showed less accuracy than all others when faces were presented in their RVF. These findings are discussed in regard to the proposed model of hostility. Confirmatory and contradictory evidence is discussed relative to current neuropsychological hypotheses on the lateralization of affective function in the cerebral cortex and the role of physiological arousal in affective facial perception. Clinical implications of results are further discussed in relation to anger management interventions in hostile men. Recommendations for future research on hostility, relative to design and new directions, are made. / Ph. D.

Sixty right-handed men, half classified as anxious without depressive symptoms, the other half as nonanxious, participated in a tachistoscopic study of the influence of anxiety without depression on hemispheric processing of Ekman and Friesen's (1976) happy, angry, and neutral emotional faces. Results were counter to hypotheses, where anxious subjects' reaction times to affective valences were slower than nonanxious subjects. Additionally, anxious subjects failed to demonstrate a negative affective bias for neutral stimuli. Results are discussed in terms of arousal theory, where anxious subjects may be considered overaroused for the tachistoscopic task, thereby exhibiting slower reaction times to affective stimuli. More specific neuropsychological hypotheses for anxious individuals without depression versus nonanxious individuals in terms of concurrent anterior dysfunction and posterior hyperarousal are discussed. / Master of Science

Based on Luria's notion of functional neuronal systems, reading has been hypothesized to require the adequate functioning of both the anterior and posterior cerebrum. Failure to be able to read has been hypothesized to be the result of dysfunction occurring anywhere throughout those functional units. In adults, anterior and posterior language problems have been established by assessing verbal fluency. Nonfluent output has been associated most often with anterior dysfunction, while fluent output has occurred with posterior dysfunction. The primary purpose of the present exploratory study was to evaluate the utility of verbal fluency as a dimension on which to classify children with the language problem of dyslexia. Subjects first were identified as dyslexic readers (DR) or normal readers (NR) based on a statistical formula which determined whether IQ and reading achievement scores were significantly discrepant. A traditional measure of verbal fluency then was used to determine that the DR children were less fluent than NR children. DR children subsequently were classified into nonfluent (NF) and fluent (F) subgroups. Initial validation for die fluency construct then was established by examining children's performance on other language and motor tasks associated with anterior and posterior functioning. As predicted, the DR-NF children performed more poorly or displayed specific deficits on tasks purported to tap anterior functioning (e.g. verbal memory, motor perseveration, and vigilance) while DR-F and NR children did not. A dual processing model was proposed to explain the findings for the DR-NF children. Limitations, implications for the treatment of DR children, and directions for future research are outlined / Ph. D.