The Etiology of Long-Term Stable Mild Cognitive Impairment
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2020-06-26
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Abstract
Mild cognitive impairment (MCI) is referred to as the prodromal phase of a progressive disease (i.e., neurodegeneration) that results in dementia, however a substantial portion (ranging from 5-30%) remain cognitively stable over the long term (sMCI). The etiology of sMCI is unclear but may be due to cerebrovascular disease (CVD) and/or neuropsychiatric symptoms. The purpose of this study is to empirically determine whether CVD and neuropsychiatric symptoms are significant contributors to cognitive impairment, in the absence of neurodegenerative pathology, in individuals with sMCI. A retrospective analysis was performed on neurodegenerative and CVD data acquired at autopsy and in vivo measures of neuropsychiatric symptoms from the National Alzheimer’s Coordinating Center data repository. Individuals with sMCI (n = 28) were compared to those with MCI who declined over a 5 to 9-year period (dMCI; n = 139) on measures of neurodegenerative pathology, CVD, and neuropsychiatric symptoms. Neurodegenerative pathology (i.e., amyloid plaques, neurofibrillary tangles, and cerebral amyloid angiopathy) was significantly higher in the dMCI group compared to the sMCI group. Microinfarcts were the only CVD pathology that was associated with group membership; these were more frequent in the sMCI group compared to the dMCI group. Neuropsychiatric symptoms, measured using the Geriatric Depression Scale and the Neuropsychiatric Inventory Questionnaire, showed no difference between groups. In conclusion, the findings suggest that the etiology of sMCI is not primarily due to neurodegenerative disease, and CVD (excluding microinfarcts) and neuropsychiatric symptoms contribute to cognitive impairment similarly in both the sMCI and dMCI groups. Microinfarcts appear to contribute significantly to the cognitive impairment in sMCI and may be occurring in isolation.
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Sharma, M. J. (2020). The Etiology of Long-Term Stable Mild Cognitive Impairment (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.