不同時期失智症之認知功能

Cognitive Function in Different Stages of Dementia

台灣地區的失智症以阿茲海默症最為常見，而認知功能在診斷失智症方面是一項相當重要的工作。近年來學者所發展出的認知功能障礙篩檢量表（Cognitive Abilities Screening Instrument, CASI），目地是希望能做為失智症的篩檢工具，同時可以監測疾病的進行，並提供認知功能障礙的模式，然而目前尚未有文獻提到有關這方面的研究。中文版的CASI則經過正式的英翻中與中翻英兩階段翻譯手續以確認其內容與原施測題目相當，並經過中文的信效度分析證實可用於失智症病人的評估。本文就這個工具應用於不同時期失智症的病人所得的結果作分析，並與MMSE做比較。共有97位病人進入研究，其中非失智症病人佔16位，而失智症病人佔81位，CASI與MMSE的得分均可有意義的區別失智症與非失智症病人，然而CASI比MMSE更能有效區別失智症的嚴重度。就不同嚴重度的失智症病人而言，CASI的認知功能細項缺損也有不同的表現，這當中以定向感最能做有意義的區分。我們的結果的與臨床上的觀察和以其他工具所測得的結果類似，顯示CASI可以監測疾病的進行，並依不同嚴重度的失智症提供不同認知能功障礙的模式。

The Cognitive Abilities Screening Instrument (CASI) provides quantitative assessment in 10 cognitive domains which includes long-term memory, orientation, attention, concentration/mental manipulation, short-term memory, list-generating fluency, language, abstraction, judgement and drawing ability. This test is specifically designed for cross-cultural applicability and is useful in screening for dementia, in monitoring disease progression and in providing profiles of cognitive impairment. However, the cognitive profiles in different stages of dementia are not evaluated. We present the pattern of cognitive dysfunction in Alzheimer's disease from early to moderate severity. There are 16 non-dementia controls and 81 patients of Alzheimer's disease (AD). The diagnosis of AD was made by the diagnostic criteria of DSM-IV. The severity of the disease was staging by Clinical Dementia Rating scale (CDR). Patients and non-dementia controls were all evaluated by CDR, CASI and MMSE. We used multiple variances regression method to correct age and education effect. The corrected scores were analysis by t-test and the level of significant was setup to 0.01. Eighty-one AD patients, 28 males and 53 females, were classified by CDR into the early stage (CDR=0.5, 20 patients), mild stage (CDR=1, 37 patients) and moderate stage (CDR=2, 24 patients) of the dementia. The result of CASI in each category showed significant difference between AD and controls. Patients with early dementia showed significantly inferior to the control groups in orientation, short-term memory and language (p≦0.01). In mild dementia patients, list-generating fluency, abstraction, judgement drawing, long-term memory and concentration/mental manipulation also show significantly decline as compared with normal control (p≦0.01). Attention shows significant decline (p≦0.01) in CDR stage 2 as compared with non-dementia controls. Orientation is the only cognitive item that shows significant decline during three stages of dementia. Our study shows that CASI can provide different patterns ot cognitive impairment from early to moderate stage of the dementia. It shows more prominent and more global cognitive dysfunction as the disease become worse. The findings are compatible with the pathological changes in AD. reflecting the progression loss of neuron from medial temporal region to other regions and their connections. However, our data are cross-sectional and it is inappropriate to extrapolate these data to indicate patterns of progression in AD. Longitudinal follow up these patients will solve the issues.