評估口腔健康狀態與認知功能之時序性關係： 社區無失智症老年人口腔健康狀態不佳預測認知功能下降

Abstract

背景：以往探討口腔健康狀態和認知功能的研究多著重於牙周疾病或缺齒與整體認知功能之關係。然而長者通常同時會有不只一種的口腔健康問題，這些問題也可能會影響不同的認知範疇。再者，在過去研究當中，探討牙齒缺損與認知功能之關聯性的縱貫性研究較為缺乏，因此本研究旨於填補這些研究的空缺。 研究方法：本研究為一項前瞻性世代研究“台灣老年認知功能流行病學研究”（2011至今）的一部分，共368位65歲以上的台灣社區老人納入本研究。研究資料包括基線（2011-2013年）及第一次和第二次追縱的總體認知功能（蒙特利爾認知評估量表：總分低於24分者定義為認知障礙）以及四種認知範疇（邏輯記憶：魏氏記憶量表第三版（Wechsler Memory Scale-Third Editions, WMS-III）中的I回憶及主題測驗、II回憶及主題測驗；執行功能：路徑描繪測驗A及B；專注力：順向及反向記憶廣度測驗測驗；語言流暢度：語言流暢度測驗-水果、魚類及蔬菜）。九項認知功能領域測驗分別依其平均值和標準差計算出相對應的Z值，接著依照基線時這些Z值的排序，將受試者人數進行三切，Z值為最低三分之一的長者（T1）定義為該領域認知功能表現較差，Z值為較高之三分之二（T2+T3）則定義為認知功能表現較佳，第一次追蹤和第二次追蹤的認知功能則根據上述基線之切點來定義）。基線時之口腔健康狀態則包括牙齒缺損、牙周疾病及咀嚼能力三項。牙齒缺損定義為有齲齒、殘根、牙齒磨損、牙齒頸部磨損或牙齒斷裂，這些牙齒狀況均無者則為無牙齒缺損。牙周疾病的定義分為兩種，第一種依嚴重程度分為三組，無牙周疾病為沒有牙齦炎、牙結石或牙周病任一項，中度牙周疾病則為有牙齦炎或牙結石，但沒有牙周病，重度牙周疾病則為有牙周病；第二種定義則將中度及重度牙周疾病合併為有牙周疾病組，無牙周疾病定義同上。咀嚼能力的定義分為二種，第一種定義正常咀嚼能力為沒有牙齒磨損、牙齒頸部磨損、牙齒斷裂、殘根或缺齒，中度咀嚼能力為有牙齒磨損、牙齒頸部磨損或牙齒斷裂，低度咀嚼能力為有殘根或缺齒；第二種定義正常咀嚼能力為沒有牙齒磨損、牙齒頸部磨損、牙齒斷裂、殘根或缺齒；異常咀嚼能力為有牙齒磨損、牙齒頸部磨損、牙齒斷裂、殘根或缺齒。廣義線性混合模型則用來評估基線口腔健康狀態與基線、兩年及四年追蹤的認知功能之關聯性，模型中另調整重要的共變項（例如：性別、年齡、教育年數及載脂蛋白E e4帶原狀態）。 結果：與無牙齒缺損的長者相比，有牙齒缺損的長者的邏輯記憶（II回憶測驗：勝算比=1.65，95%信賴區間=1.10至2.49）和執行功能（路徑描繪測驗B：勝算比=1.63，95%信賴區間=1.07至2.48）的表現較差。有重度牙周疾病的長者在執行功能（路徑描繪測驗A：勝算比=2.01，95%信賴區間=1.05至3.87）的表現較無牙周疾病的長者差，中度牙周疾病的長者比起無牙周疾病者則無顯著差異。 結論：基線時之口腔健康狀態不佳會有較差認知功能表現（牙齒缺損與邏輯記憶功能和執行功能；重度牙周疾病與執行功能）。由於本研究的受試者於基線時都尚未失智，口腔健康狀態不佳為認知功能障礙的危險因子，因此可以藉由失智症疾病前期的口腔健康狀態預測長者日後的認知功能的狀態，除了需積極推廣口腔保健知識，也需提倡各年齡層的民眾養成定期檢查牙齒的習慣。

Background: Previous studies exploring the association between oral health and cognitive function mainly focused on the relationship between periodontal diseases or teeth loss and global cognitive function. However, the older adults usually have various oral health conditions, which have known to affect different cognitive domain. Moreover, few studies have explored the relationship between tooth defect and cognitive function. Therefore, this study aimed to fill out these research gaps. Method: This is a prospective cohort study, which is part of “Taiwan Initiative for Geriatric Epidemiological Research” (2011-present). A total of 368 community-dwelling elders (65+) were included for analysis. The dependent variables included global cognition (Montreal cognitive assessment-Taiwan version, MoCA-T. MoCA-T score less than 24 point indicated cognitive impairment) and domain specific cognition (logical memory was assessed by I&II–recall and thematic (Wechsler Memory Scale-Third Edition, WMS-III); executive function was assessed by trail making test A and B; attention was assessed by digit span-forward and backward; verbal fluency was assessed by verbal fluency test-fruit, fish and vegetable. For nine cognitive function tests, the Z-score was calculated according to the mean and standard deviation at baseline, poor performance of cognitive function was defined as the lowest tertile (T1) of score in cognitive functions over 4 years. Independent variables were baseline oral health status, which included tooth defect, periodontitis and chewing ability. Tooth defect was defined as the existence of any of dental conditions (caries, residual root, tooth wear, cervical abrasion or tooth break). No tooth defect was defined as lack of the dental conditions list above. Periodontitis was grouped based on disease severity. No periodontitis was defined as no gingivitis, calculus or periodontal disease. Moderate periodontitis was defined as the existence of any of the dental conditions (gingivitis or calculus). Severe periodontitis was defined as having periodontal diseases. Chewing ability was grouped based on the degree of chewing ability. Normal chewing ability indicated lack of the following dental condition: tooth break, tooth wear, cervical abrasion, residual root or teeth loss. Moderate chewing ability was defined as the existence of any of the dental conditions (tooth break, tooth wear or cervical abrasion). Poor chewing ability was defined as the existence of any of the following dental conditions (residual root or teeth loss). The generalized linear mixed models were used to estimate the association between oral health and cognitive function adjusting for important covariates (age, sex, years of education, Apolipoprotein E e4 status, depressive symptoms, diabetes mellitus, hypertension, hyperlipidemia, higher income and time). Results: We found elders with tooth defect had poor performance of cognitive function (logical memory II–recall test assessed by WMS-III: odds ratio = 1.65, 95% confidence interval = 1.10 - 2.49; executive function assessed by trail making test B: OR = 1.63, 95% CI = 1.07 - 2.48). In addition, the elders with severe periodontitis was associated with increased risk of poor performance of cognitive function (executive function assessed by trail making test A: OR = 2.01, 95% CI = 1.05 - 3.87). However, the elders with moderate periodontitis was not associated with increased risk of poor performance of cognitive function (executive function assessed by trail making test A: OR = 1.28, 95% CI = 0.73 - 2.27). Conclusion: Over 4-years follow up, the elders with tooth defect or severe periodontitis were associated with poor performance of cognition (logical memory and executive function). Our study participants had normal cognition at baseline. Poor oral health is a risk factor for poor performance of cognition. Therefore, baseline dental health status allow us to predict following cognitive function in the pre-clinical phase of dementia. In addition to actively promote of oral hygiene, it is recommended to have regular dental check-up.