| Background: Mild Cognitive Impairment (MCI) is presently the most widely cited concept, which refers to non-demented aged persons with a mild memory or cognitive impairment that cannot be accounted for by any recognized medical or psychiatric condition. Elderly individuals with MCI are judged to have a high probability of evolving towards AD. Recognization of the cognitive manifestations of MCI, as well as their early diagnostic methods, is of great value for the identification of people at potential risk of AD with a view to early therapeutic intervention. Objective: In this paper we took a cross-sectional study on the memory and cognitive functions in elderly individuals with subject memory complaints. The purpose of this study included: ?To discuss the diagnostic criteria of MCI and its feasibility; (2) To evaluate the heterogeneity of cognitive functions in elderly individuals with subject memory complaints, and its relationship with MCI. (3) To evaluate the characteristics of the cognitive impairments of MCI. ?To find more sensitive cognitive variables for the detection of MCI. Methods: 34 consecutively evaluated subjects with memory complaints wereselected, and 15 of them were diagnosed as MCI according to 17 neuropsychological tests from Clinical Memory Scale, WAIS-RC and other batteries, while the others were classified as control group. The difference of these neuropsychological variables between MCI and control group was compared by using t test or analysis of covariance. Q-type cluster analysis was applied on 17 neuropsychological variables. Finally a discriminatory analysis was applied for selecting the best tests in differentiating MCI from control group. Results: The primary distinction between control subjects and subject with MCI was in the area of memory. Although the MMSE and PIQ of MCI group were significantly lower when compared with control group (pO.Ol), the general cognitive function of these subjects was still normal. 13 records out of 17 items of the performance were poorer in MCI group when compared with control group (p<0.05). Six clusters were extracted, one representing cognitively successfully aged, another representing individuals at risk for dementing diseases and all of them were diagnosed having MCI. One cluster was characterized by a bit lower of the overall cognitive functions but significantly reduced in memory, and all of subjects had a diagnosis of MCI. The other three clusters had a wide range of cognitive performance, representing normal or usual aging related to forgetfulness and slowness of elders. Our criteria of MCI received a sensitivity of 100% and specificity of 67.86%, respectively, when results of cluster were taken as an objective method. Three of the five Clinical Memory Scale items were discriminated as the best tests to differentiate MCI from control group, which got a total accurate rate of 100%. In another discriminatory function analysis, imaging free recall, human picture recall and Tail Making A, which were selected from9 cognitive variables, received a total accurate rate of 96.67%. Tail Making A and Clock Drawing Test, whose sensitivity and specificity was 83.33% and 84.21%, respectively, received a total accurate rate of 83.77% in differentiating at-risk individuals from non-risk individuals. Conclusion: (1): The MCI criteria we had established in this study was reasonable in items setting and operating. Both the sensitivity and P error reached our requirement of the study design, indicating that it is feasible clinically. (2): Subjects with MCI exhibited a decline in multi-cognitive function and had a similar changes in episodic memory, visuospatial skill, and psychomoter speed with early stage of AD. (3): In the transitional zone from normal aging to the very early stage of AD, the cognitive profiles is heterogeneity, which consisted of successful aging and usual or normal aging, as well as more serious cognitive impairment at risk for dementing diseases. Samples of elderly individuals should not be treated as homogeneous in c... |
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