Ball S L, Holland A J, Huppert F A, Treppner P, Watson P, Hon J
Section of Developmental Psychiatry, Department of Psychiatry, University of Cambridge, Douglas House, 18b Trumpington Road, Cambridge CB2 2AH, UK.
J Intellect Disabil Res. 2004 Sep;48(Pt 6):611-20. doi: 10.1111/j.1365-2788.2004.00630.x.
Dementia because of Alzheimer's disease (AD) commonly affects older adults with Down's syndrome (DS). Methods are needed, with established concurrent and predictive validity, to facilitate the diagnostic assessment of dementia, when it is complicated by pre-existing intellectual disabilities (ID). We report on the reliability and validity of a modified version of the Cambridge Examination for Mental Disorders of the Elderly (CAMDEX) informant interview, for use when assessing people with DS suspected as having dementia.
As part of a previous epidemiological study of older people with DS, the CAMDEX informant interview was used to determine the prevalence of dementia. The 74 people with DS included at that time (Time 1) had also completed the Cambridge Cognitive Examination (CAMCOG), the neuropsychological assessment from the CAMDEX schedule. Fifty-six were assessed again 6 years later (Time 2). Based on the CAMDEX informant interview, nine of the 74 at Time 1, and 11 of the 56 at Time 2, were found to meet clinical criteria for AD. Forty-one scored above floor on the CAMCOG at Time 1 and were included in the analysis of cognitive decline. Concurrent validity was established by comparing diagnosis at Time 2 with independent evidence of objective decline on cognitive tasks since Time 1. Predictive validity was established by examining how accurately diagnosis at Time 1 predicted both cognitive decline and future diagnosis. Inter-rater reliability was determined by comparing the level of agreement between two raters.
CAMDEX-based diagnosis of AD was shown to be consistent with objectively observed cognitive decline (good concurrent validity) and to be a good predictor of future diagnosis. Although numbers are small, some support is also provided for the accuracy with which diagnosis predicts cognitive decline. Inter-rater reliability was good with Kappa > 0.8 for 91% of items and > 0.6 for all items.
The use of the modified CAMDEX informant interview enables the structured collection of diagnostic information, so that a valid and a reliable diagnosis of dementia can be made in those with pre-existing ID, using established diagnostic criteria.
阿尔茨海默病（AD）所致痴呆症通常影响患有唐氏综合征（DS）的老年人。当痴呆症并发先前存在的智力障碍（ID）时，需要具有既定同时效度和预测效度的方法来促进痴呆症的诊断评估。我们报告了修订版的《剑桥老年人精神障碍检查表》（CAMDEX）知情者访谈的信度和效度，该访谈用于评估疑似患有痴呆症的DS患者。
作为先前对老年DS患者进行的一项流行病学研究的一部分，使用CAMDEX知情者访谈来确定痴呆症的患病率。当时纳入的74名DS患者（时间1）也完成了《剑桥认知检查表》（CAMCOG），这是CAMDEX检查表中的神经心理学评估。6年后（时间2）对其中56人再次进行了评估。根据CAMDEX知情者访谈，时间1的74人中9人，时间2的56人中11人被发现符合AD的临床标准。41人在时间1的CAMCOG上得分高于地板效应分数，并被纳入认知衰退分析。通过将时间2的诊断与自时间1以来认知任务客观衰退的独立证据进行比较，确立了同时效度。通过检查时间1的诊断对认知衰退和未来诊断的预测准确性，确立了预测效度。通过比较两名评估者之间的一致程度来确定评估者间信度。
基于CAMDEX的AD诊断与客观观察到的认知衰退一致（良好的同时效度），并且是未来诊断的良好预测指标。尽管样本量较小，但也为诊断预测认知衰退的准确性提供了一些支持。评估者间信度良好，91%的项目卡方值>0.8，所有项目卡方值>0.6。
使用修订版的CAMDEX知情者访谈能够有组织地收集诊断信息，从而可以根据既定的诊断标准，对先前存在ID的患者进行有效且可靠的痴呆症诊断。
