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  • 學位論文

認知正常中老年人大腦白質徑完整性與單一及雙重任務步態表現之關聯性:擴散頻譜造影研究

Relationships between Structural Integrity of Cerebral White Matter Tracts and Single- and Dual-Task Gait Performance in Cognitively Normal Middle-Aged and Older Adults: A Diffusion Spectrum Imaging Study

指導教授 : 湯佩芳

摘要


背景與目的:步態表現與腦白質徑皆會隨著年齡而退化,然而兩者間之關係尚未被完整探討。本研究旨在探討:在認知正常的中老年族群中,其單一與雙重任務下時間及空間步態參數是否可歸類為數個獨立的步態面向,且特定腦白質徑完整性是否與步態面向的表現有獨立的相關性。方法:本研究納入103名50歲以上(平均64.3 ± 5.6歲)認知功能正常之中老年人。受試者均接受心智與體能評估;單一、動作雙重、與認知雙重任務三種情境下舒適速度行走之步態評估;以及腦部磁振造影(Magnetic Resonance Imaging,MRI)影像掃描。腦部影像包含T1-權重、T2-權重及擴散頻譜造影(diffusion spectrum imaging)等影像資料。步態資料之收集與分析皆使用GaitMatIITM,分析得三種情境下之八個步態時間及空間參數以及其變異性。透過T1-權重影像及T2-權重影像資料分析,分別取得量化之腦體積及腦白質病變嚴重度目測評級;擴散頻譜影像資料則採以路徑為基礎之自動化分析(tract-based automatic analysis),得到76條腦白質徑之普擴散不等向性值(general fractional anisotropy),以代表纖維束之完整性。統計分析預計採用PASW 18.0軟體進行主成分分析(principle component analysis),分析三種情境下之步態面向,並以單變數迴歸分析先找出與各情境下各步態面向有關的腦白質徑完整性。最後以多變數迴歸分析,找出影響各情境下各步態面向之最重要腦白質徑完整性因子。所有迴歸分析中皆會控制八個共變項。 結果:主成分分析顯示,單一任務下之步態參數可歸類為步調、節律、相位、支撐底面積、步調變異、節律變異-相位變異等六個面向;動作與認知雙重任務下之步態參數則可歸類為節律、相位、支撐底面積、步調變異-節律變異、相位變異等五個面向。多變數迴歸分析結果顯示,單一任務下,影響步調、相位、與支撐底面積面向之腦白質徑完整性分別為右側皮質脊髓徑(β = 0.236, p = 0.018)、右側弓狀束(β =-0.205, p = 0.035)、與左側鉤束(β = 0.236, p = 0.015)。動作雙重任務下,影響相位、支撐底面積、步調變異-節律變異、與相位變異面向之腦白質徑完整性分別為左側額葉紋狀體徑(β = 0.216, p = 0.025)、左側皮質脊髓徑(β = 0.206, p = 0.049)、左側扣帶迴徑(β = 0.359, p = <0.001)、與胼胝體徑(β = -0.251, p = 0.006)。認知雙重任務下,影響相位、支撐底面積、與相位變異面向之腦白質徑完整性分別為右側上縱束(β = 0.241, p = 0.014)、右側扣帶迴徑(β = 0.234, p = 0.017)、與左側丘腦輻射徑(β =-0.309, p = 0.003)。 討論與結論:中老年人單一任務及兩種雙重任務下之步態參數可被歸類為數個但稍有不同的獨立步態面向。在單一任務下,步態表現與動作及邊緣系統相關之腦白質徑完整性較有關。動作雙重任務下,動作皮質區、基底核及胼肢體等負責動作協調之相關神經束完整性越高,步態表現越佳。認知雙重任務下,與整合認知、感覺與動作訊息相關之大腦皮質-大腦皮質或大腦皮質-大腦皮質下神經束完整性越高,步態表現越佳。

並列摘要


Background: Gait performance and white matter tracts both decline with age. However, the relationship between the degeneration of white matter tracts and gait performance in middle-aged and older adults has not been comprehensively studied. Therefore, the aims of this study were to investigate whether spatiotemporal gait parameters under single- and dual-task walking conditions in cognitively normal middle-aged and older adults could be classified into independent domains, and whether the integrity of specific cerebral white matter tracts independently correlated with the these gait domains. Methods: One-hundred-and-three cognitively normal middle-aged and older adults over the age of 50 years (mean 64.3 ± 5.6 years) participated in this study. All participants received assessments of mental status, motor function, gait performance of comfortable-speed walking under single-task, motor dual-task and cognitive dual-task conditions, and brain MRI scans, including the T1-weighted, T2-weighted, and diffusion spectrum imaging (DSI). The GaitMatIITM was used for collection and analysis of spatiotemporal gait parameters and their stride-to-stride variabilities under the three conditions. Quantified brain volume measures and the visual rating of white matter lesions were obtained from T1-weighted and T2-weighted imaging, respectively. Values of general fractional anisotropy (GFA), which indicated the microstructural integrity of white matter fiber tracts, of 76 white matter fiber tracts were obtained from the DSI, using a validated tract-based automatic analysis technique. Principle component analysis (PCA) was used to classify gait domains under the three conditions. Univariate regression analyses were used to determine the tracts independently correlated with scores of gait domains under each condition, and multivariate regression analyses were used to determine the most important tracts that independently affacted scores of gait domains. Eight covariates were used in all regression analyses. Results: The gait domains emerged from the PCA of single-task gait were: pace, rhythm, phase, base of support, pace variability, and rhythm variability-phase variability; and those emerged from the PCA of motor and cognitive dual-task gait were: rhythm, phase, base of support, pace variability-rhythm variability, and phase variability. Multivariate regression analyses showed that the integrity of the right corticospinal tract (β = 0.236, p = 0.018), right arcuate fasciculus (β =-0.205, p = 0.035), and left uncinate fasciculus (β = 0.236, p = 0.015) independently contributed to the pace, phase, and base of support domains of single-task gait performance, respectively. The integrity of the left frontostriatal tracts (β = 0.216, p = 0.025), left corticospinal tract (β = 0.206, p = 0.049), left cingulate bundle (β = 0.359, p = <0.001), and callosal tract (β =-0.251, p = 0.006) independently contributed to the phase, base of support, pace variability-rhythm variability, and phase variability domains of motor dual-task gait performance, respectively. The integrity of the the right superior longitudinal fasciculus (β = 0.241, p = 0.014), right cingulate bundle (β = 0.234, p = 0.017), and left thalamic radition (β =-0.309, p = 0.003) independently contributed to the phase, base of support, and phase variability domains of cognitive dual-task gait performance, respectively. Discussion & Conclusions: Spatiotemporal gait parameters of single-task and dual-task walking in middle-aged and older adults could be categorized into different independent domains. The single-task gait performance correlated mainly with the integrity of white matter tracts of the motor and limbic systems. The better the integrity of white matter tracts related to the motor cortex, basal ganglia, and corpus callosum was, the better the motor dual-task gait performance was. The better the white matter tracts integrity of cortico-cortical and cortico-subcortical tracts integrating cognitive, sensory, and motor systems, the better the cognitive dual-task gait performance was.

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