Browsing by Author "Alrazi, Tazrina"

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    Brain 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, Jeffrey
    Mild 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.