Browsing by Author "Smith, Eric"
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- ItemOpen AccessAdverse childhood experiences and health among indigenous persons experiencing homelessness(2021-01-07) Smith, Eric; Milaney, Katrina; Henderson, Rita I; Crowshoe, LyndonAbstract Background Current literature has established that adverse childhood experiences (ACEs) are associated with the onset of a variety of physical, mental, and behavioural illnesses. However, there are few studies that have thoroughly examined this association in low-income or marginalized groups. Methods To address this knowledge gap, this study used self-reported data on childhood experiences and adult health outcomes in a sample of 91 Indigenous persons experiencing homelessness. While the primary focus of the study was to assess the relationship between ACEs and health status, we also assessed reports on use and perceptions of health care services to test for potential illness-mitigating factors. Results Results indicated that reported number of ACEs was significantly associated with reported levels of mental illness (p < .001, d = 1.12). Significant associations were not observed for physical illness or patterns of substance use. We also found that the number of reported ACEs was significantly correlated with the number of formal health care services that an individual used (r = 0.32). Conclusions Our results reveal that the relationship between ACEs and adult illness is not as deterministic as the current literature suggests. Access to formal health care services may allow individuals to mitigate their adverse health, thereby eliminating some of the effects of ACEs. Conversely, current tools used to measure ACEs may not translate to an Indigenous population, which speaks to a need to revise ACE related surveys to include additional adversity categories.
- ItemOpen AccessBrain Mechanisms of Associative Memory Deficits in Mild Cognitive Impairment, With or Without Parkinson’s Disease(2021-06-14) Alrazi, Tazrina; Monchi, Oury; Goodyear, Bradley; Smith, Eric; Dunn, JeffreyMild cognitive impairment (MCI) is a condition of minor cognitive difficulties compared to age-matched healthy individuals. Independent activities of daily living are unaffected in MCI. MCI is a major risk factor for the development of dementia, including in patients with Parkinson’s Disease (PD). Individuals with and without PD with MCI might eventually develop dementia. MCI might give an opportunity to initiate interventional strategies to prevent dementia or prolong the duration to get dementia. A deficit in associative memory, the recollection of an association between two or more items, is a marker of early cognitive impairment in MCI. We hypothesized that the neural origins of associative memory deficits differ between MCI with and without PD, which is very important for understanding the MCI process. In this thesis, functional magnetic resonance imaging (fMRI) was used to investigate brain mechanisms of associative memory deficits in MCI with or without PD and compared with age-matched healthy controls. Study participants performed a face-scene associative memory task inside the MRI scanner. The results of this thesis demonstrate different mechanisms of associative memory deficits in MCI with and without PD. PD with MCI (PD-MCI) shows reduced activations in fronto-parietal, fronto-striatal and temporal regions compared to healthy and MCI without PD (non-PD-MCI) during the associative memory task. Non-PD-MCI shows increased activations in fronto-parietal, and temporal regions compared to healthy and both PD groups during the task. PD without MCI (PD-non-MCI) shows increased activations in fusiform gyrus compared to healthy and increased activations in fronto-striatal regions compared to PD-MCI. Both PD groups demonstrate reduced fronto-parietal activations compared to healthy. PD-non-MCI shows similar associative memory performance as healthy while MCI with or without PD groups show poorer performance on the task compared to healthy. Together, these results indicate that increased activations of specific brain regions in PD-non-MCI might be potentially compensatory, whereas increased aberrant activations in non-PD-MCI do not compensate for their underlying cognitive deficiency. Longitudinal follow-up of our subjects could indicate contribution of these brain regions in MCI and potential dementia. Our findings contribute to the understanding of brain functionality in MCI in the elderly with or without PD.
- ItemOpen AccessIdentifying the Neuropsychological Profile of Cerebral Amyloid Angiopathy(2015-07-13) Case, Nevicia; Smith, EricCerebral amyloid angiopathy (CAA) occurs when the protein, beta-amyloid, deposits onto blood vessels in the brain, often resulting in cognitive impairment. This study aims to identify the neuropsychological profile of CAA by comparing CAA participants to the normal population and cognitively-similar patient populations, distinguishing between CAA syndromes, and determining whether white matter hyperintensity volume or APOE ε4 mediate cognitive impairment. Thirty-four CAA, 16 Alzheimer’s disease, 69 mild cognitive impairment, and 27 minor ischemic stroke participants underwent neuropsychological testing. Cross-sectional data revealed lower performance on tests of perceptual speed, episodic memory, and executive functioning in CAA participants when compared to the normal population (t(33) = -3.76, p = <0.001; t(32) = -2.45, p = 0.02; t(33) = -6.21, p = <0.001; respectively). Overall, CAA was most cognitively similar to vascular cognitive impairment. Larger sample sizes and longitudinal analyses in future will help to advance understanding of cognitive deficits associated with CAA.
- ItemOpen AccessNeuroimaging Biomarkers of Alzheimer’s Disease and Cerebrovascular Disease in Patients with Subjective Cognitive Concerns and Mild Cognitive Impairment(2015-09-02) Wang, Xinjue Rachel; Smith, Eric; Frayne, RichardIn these studies, patients with subjective cognitive concerns (SCC; n = 43) and mild cognitive impairment (MCI; n = 18), were compared using neuroimaging biomarkers for β-amyloid, white matter hyperintensities (WMH) of presumed vascular origin, and cerebral perfusion. Higher WMH burden was found in SCC compared to MCI (p = 0.02). In the whole cohort, there was a correlation between higher β-amyloid accumulation and lower left (p = 0.02) and right temporal gyrus perfusion (p = 0.05), while higher WMH burden was associated with lower perfusion in the cortical grey matter (p = 0.01), posterior cingulate cortex (p = 0.02) and right temporal gyrus (p = 0.01). Exploratory comparisons suggested lower perfusion in the left temporal gyrus and anterior cingulate cortex in amnestic MCI (n = 12) compared to non-amnestic MCI (n = 6). These findings suggest that pathologies consistent with dementia are evident in early cognitive decline.
- ItemOpen AccessPredicting Cognitive Decline in Patients with TIA and Minor Stroke(2016) Munir, Muhammad Amlish; Barber, Philip; Smith, Eric; Frayne, RichardDementia is an incurable neurocognitive disorder and recognizing early pathological biomarkers can help to predict future dementia. Transient Ischemic Attack (TIA) and minor stroke patients are at risk of dementia. We hypothesized that TIA and minor stroke patients experience higher brain atrophy rates and that baseline brain and hippocampal volumes may predict cognitive decline at 3 years. Our results suggest that TIA and minor stroke patients experienced a higher percent brain atrophy rate over 3 years compared to controls. Cognitive decline was observed at 3 years for tests assessing processing speed, and short and long delay free recall. Age was a predictor of decline in processing speed and time was a predictor for short and long delay free recall as well. Higher whole-brain atrophy and cognitive decline at 3 years suggests that TIA/minor stroke patients are a high-risk population for dementia.
- ItemOpen AccessRelationship between Blood Pressures and Brain Volumes: Systematic Review and Analysis of A Canadian Population-Based Study(2014-01-07) Batool, Saima; Smith, Eric; Frayne, RichardLong-standing hypertension has been associated with global and regional brain atrophy. Little is known regarding the timing of atrophy onset and its relationship with duration and severity of hypertension. A systematic literature review was performed to identify the relationships between hypertension and brain atrophy measured using neuroimaging, to summarize the existing knowledge and to identify areas for future investigation. Most studies identified that higher systolic blood pressure was associated with late-life brain atrophy; however, these studies did not include a concurrent assessment of brain imaging in mid-life, and participants in these studies were middle-aged in the 1980s when definitions of blood pressure (BP) were more permissive and population BP control was poorer. To investigate the relationship between BP and brain atrophy in mid-life in a contemporary cohort, brain magnetic resonance (MR) images were analyzed in 778 individuals participating in the population-based PURE-MIND study, a sub-study of the international Prospective Urban Rural Epidemiologic (PURE) Study designed to identify the risk factors for common non-communicable diseases. MR data were processed for global and regional brain volumes and cortical thickness. No significant association was seen between brain volume and hypertension, after controlling for age and gender. However, few participants had markedly elevated BP, probably due to improving population-wide control of hypertension due to lower thresholds for successful treatment than in past decades. Analysis showed that brain atrophy is not a common consequence of mid-life hypertension in today’s Canadians. It is possible that aggressive screening and control of mid-life BP might prevent atrophic changes.
- ItemOpen AccessSEED: A Mixed-Methods Study of Stroke-related Experiences and Priorities of Elderly Living with Dementia or Disability, their Family Caregivers, and Physicians.(2024-06-13) Betzner, William; Ganesh, Aravind; Smith, Eric; Demchuk, Andrew; Lashewicz, Bonnie; Dukelow, SeanAcute ischemic stroke (AIS) results from blood flow loss to part of the brain and is a leading cause of disability worldwide. Pre-stroke dementia is defined as evidence of substantial cognitive decline from a previous performance level, resulting in the person needing help with activities of daily living. This cognitive disorder is associated with higher AIS risk with around 10% of AIS patients have pre-existing dementia. A further 30% of stroke patients have pre-stroke disability. Little is known about the use of stroke therapies in PLWD, as these patients have been conventionally excluded from randomized-controlled trials. We aim to develop a broad picture of the current state of AIS management for PLWD by engaging with the key stake holders–patients, caregivers, and physicians–on the matter. This is accomplished through a systematic review and meta-analysis of reperfusion outcomes in persons with pre-existing dementia, followed by a mixed-methods approach focusing on PLWD. SEED A explores the experiences of PLWD who have a stroke and their primary caregiver. SEED B investigated physician approaches toward the acute stroke management of PLWD. The representative case style survey has been disseminated worldwide to physicians to reveal trends in the stroke management of PLWD, with data collection still ongoing. The use of reperfusion therapies in PLWD has no substantial safety concerns, although there is a need for more robust data, with tailored outcomes. Perspectives shared by patients and caregivers emphasize the importance of preserving independence, and the variety of challenges of navigating dementia and disability in the acute setting and daily life after stroke. Insights from physicians highlight the complexities and nuanced decision-making involved in managing acute stroke in PLWD. These opinions highlight an acute stroke care environment where research evidence, resources and tailored treatment strategies are limited. This thesis underscores the need for including PLWD in future clinical trials and creating tailored stroke treatment strategies. Findings will be used to develop better criteria for stroke therapies and contribute to better definitions of good outcomes after stroke for PLWD. This will inform future study designs, and is relevant to clinicians, researchers, policy makers, patients, and caregivers.
- ItemOpen AccessVascular Reactivity by Blood Oxygen Level Dependent Functional MRI in Cerebral Amyloid Angiopathy: Comparison with Alzheimer's Disease and Assessment of Longitudinal Change(2014-08-15) Switzer, Aaron; Smith, Eric; Goodyear, BradleyCerebral amyloid angiopathy (CAA) refers to the deposition of Abeta (Aβ) peptides in the brains small blood vessels leading to hemorrhagic stroke and cognitive impairment. Aβ is toxic to smooth muscle cells and impairs blood flow regulation. Reduced blood oxygen level dependent (BOLD) signal amplitude in response to a visual fMRI task has recently been implicated as a surrogate marker for impaired vascular reactivity in CAA. There have been no studies investigating how the BOLD amplitude changes in other Aβ diseases that present with CAA (Alzheimer’s disease (AD) or mild cognitive impairment (MCI)), or how it changes over time in CAA. BOLD amplitudes were lowest in CAA compared to controls but were not lower in MCI or AD. BOLD amplitudes decreased over 1-year in CAA but not in controls. These results provide more evidence for the use of BOLD amplitudes as a measure of impaired vascular reactivity in CAA.