輕度阿茲海默症患者視覺組織能力與大腦葡萄糖代謝之關聯

The Relation between Visual Organization Ability and the Metabolism of Cerebral Glucose in Mild Alzheimer disease.

吳懿真(Yi-Zhen Wu)

指導教授 ： 劉景寬

高雄醫學大學/人文社會科學院/心理學系碩士班/碩士(2015年)

摘要

背景與目的：失智症是一種臨床症候群，這種症候群會影響到大腦高級皮質功能，導致患者出現多項心智功能的退化與異常，嚴重影響原已發展完成的智能狀態。阿茲海默症(Alzheimer Disease, AD)是最常見的失智症類型，目前也是一種不可逆的神經退化疾病，早期最常見的症狀是記憶力變差，無法記起新事物，隨著病程的進展，許多認知功能開始受到影響，例如視覺組織能力的缺損。本研究主要探討Hooper視覺組織測驗(Hooper Visual Organization Test, HVOT)與大腦葡萄糖代謝之關聯，並進一步檢視AD患者與健康人執行HVOT時，大腦葡萄糖代謝量的差異。本研究假設：(1)AD患者在HVOT得分顯著較健康人的得分低；(2)因正子電腦斷層(PET/CT)時間解析度相對較差，無法獲取立即性的大腦葡萄糖改變量，因此本研究推論在健康人身上，大腦視覺相關路徑(背流與腹流)葡萄糖代謝差異量與HVOT得分的關聯性較不明顯；(3)AD患者因基準期大腦葡萄糖代謝量較低，執行HVOT時會有更明顯的活化，但受到疾病病理影響，腹流路徑損傷較嚴重，因此在代償機制的作用下，背流路徑的葡萄糖代謝差異量與HVOT分數會有較明顯的正相關。
方法：研究對象分為兩組：實驗組與對照組。實驗組包括10位輕度AD患者(CDR=0.5或1)，對照組則是11位健康人。本研究以HVOT作為視覺組織能力之指標，大腦葡萄糖代謝量則使用FDG PET/CT測得，每位研究對象均接受兩次測量：基準期與測驗期，基準期測量休息狀態之大腦葡萄糖代謝，測驗期則給予HVOT作為刺激物，觀察大腦葡萄糖活化程度。
結果：相較於健康人，AD患者在HVOT的表現顯著較差。一般狀態下，AD相較於健康人，在額葉、顳葉、視覺關聯皮質、後扣帶迴、橋腦、左側前扣帶迴、左側布洛卡區的葡萄糖代謝量都顯著較低。此外，比較AD與健康人在接受HVOT測驗之前(baseline階段)與之後(testing階段)的大腦葡萄糖代謝差異量，結果發現AD測驗前後大腦葡萄糖代謝差異量與HVOT得分有顯著正相關，這些腦區包括左腦額中葉皮質、頂下葉皮質、布洛卡區、後扣帶迴皮質、顳頂葉皮質以及右腦初級視覺皮質與雙側視丘，而健康人的腦區與HVOT得分則沒有任何相關。
結論：AD具有視覺組織能力缺損。AD在執行HVOT時，所運用到的能力包括空間定位、語言、視覺、工作記憶等，以及其他高階之訊息統合能力。本研究主要貢獻在於使用FDG PET/CT探討AD患者執行HVOT時，大腦相關參與處理與運作功能的腦區。

關鍵字

阿茲海默症 ； 視覺組織能力 ； Hooper視覺組織測驗（HVOT） ； 正子電腦斷層造影

並列摘要

Background and Goal: Dementia is a clinical syndrome, which affects the patient’s cortical function and causes the degeneration and abnormality of lots of cognitive functions, influencing severely the intelligence that has finished being developed. Alzheimer disease is the most common type of dementia, and also a kind of neurodegenerative disease that is irreversible for now. The commonest earlier symptom is that it will worsen the patient’s memory, making him or her unable to memorize new things. And with the progression of disease, many cognitive functions will be influenced, such as the deficit of the ability of visual organization. In this study, we mainly discuss the relation between Visual Organization Test and the metabolism of cerebral glucose, and examine the differences in the metabolism of cerebral glucose between AD patients and the normal control when they were doing the test. The hypothesis of the study includes: (1) in the HVOT, the scores which the AD patients get are significantly lower than those which the normal control get; (2) due to the temporal resolution of PET/CT, it cannot acquire the immediate difference in metabolic rate of cerebral glucose between before the stimulation and after it; therefore, the study speculate the normal control’s relation between the difference of metabolic rate of glucose in visual pathway (dorsal and ventral) and the scores they get in the HVOT is not significant; (3) because of AD patients’ metabolism of cerebral glucose in baseline is lower than normal control, there would be significant activation of it when AD patients are doing the HVOT; ventral pathway is impaired more severely than dorsal pathway is, so the difference of metabolic rate of glucose in dorsal pathway would be significantly positively related to the scores of the HVOT.
Method: We divided the participants into two groups: the experiment group and the control group. The experiment group included 10 mild Alzheimer patients (CDR=0.5 or 1), while the control group was composed of 11 normal control. In the study, the ability of visual organization was measured by Hooper Visual Organization Test, and we used FDG Positron Emission Tomography (FDG PET/CT) to measure the metabolism of cerebral glucose, in which each participant required to be evaluated twice: baseline and testing. The baseline was to measure the metabolism of cerebral glucose during the resting state, while the testing was to be given to Visual Organization Test as stimulation so that we could see the activating degree of cerebral glucose.
Result: Compared to normal control, AD patients performed significantly worse in the Visual Organization Test. In baseline, compared to normal control’s, AD patients’ metabolic rates of glucose in frontal, temporal, associative visual cortex, posterior cingulated cortex, pons, left anterior cingulate cortex, left Broca’s region were significantly lower. In addition, after comparing the difference of metabolic rates of cerebral glucose between AD patients and normal control before doing the HVOT (baseline) and after doing it (testing), we found that AD patients’ difference of metabolic rates of cerebral glucose between before and after the HVOT was positively related to the scores of the test. These cerebral regions include left middle frontal cortex, left inferior parietal cortex, left Broca’s region, left posterior cingulated cortex, left parietotemporal cortex, right primary visual cortex, right and left thalamus, whereas the normal control’s did not relate to the metabolism of cerebral glucose in all brain regions.
Conclusion: In the study, we found out that the AD patients’ ability of visual organization positively related to the brain regions mentioned previously. Therefore, we presume when the patients were doing Hooper Visual Organization Test, the ability they were utilizing included spatial location, language, vision, working memory, and other high-order information integration. This study is a pilot for the AD patients’ condition of metabolism of cerebral glucose when they are doing the visual organization test through FDG Positron Emission Tomography (FDG PET/CT).

並列關鍵字

Alzheimer Disease ； visual organization ability ； Hooper Visual Organization Test ； Positron Emission Tomography (PET/CT)

參考文獻

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