Validity of clock drawing test (CDT), scoring by Chula clock-drawing scoring system (CCSS) in screening dementia among Thai elderly in community.

OBJECTIVE: The present paper was to study the validity of screening dementia among Thai elderly by clock drawing test (CDT). MATERIAL AND METHOD: The scoring method selected to apply with CDT was Chula clock-drawing scoring system (CCSS) that was originally developed as clinically-based in Thai elderly patients. The 669 elderly subjects gathered from "Rom Klao" community in Bangkok, Thailand were asked to perform CDT and be examined by a neurologist, using NINCDS-ADRDA diagnosis criteria for probable Alzheimer's disease (AD). CDT was scored by psychiatrists using CCSS. RESULTS: The authors found the demented by clinical diagnosis in 25 cases. Using a CCSS cutoff score of 7, CDT produced positive test results in 191 subjects. Sensitivity was 88%, the specificity was 74% and the area under receiver operation characteristics (ROC) curve was 0.91. The results also showed that comparatively to cutoff point 7, a cutoff point 6 would contribute the higher specificity of 82% and have a similar sensitivity of 88% in this community-based sample. CONCLUSION: The present study provided strong support that CDT scoring by CCSS is efficient to screen dementia in the general community with satisfactory sensitivity and specificity. However modifying the CCSS cutoff score from 7 to 6 increases the specificity and is proposed to be applied in the community.

Rapid detection of apolipoprotein E genotypes in Alzheimer's disease using polymerase chain reaction-single strand conformation polymorphism.

Apolipoprotein E (APOE) gene on chromosome 19q13.2 is encoded by three common alleles designated as epsilon2, epsilon3 and epsilon4. In Alzheimer's disease (AD) the epsilon4 allele is over-represented and is considered to be a major genetic risk factor. Several methods have been developed to determine APOE genotypes. Among them, polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) appears to be highly reliable. In this study, we improved the nonisotopic PCR-SSCP method for determining APOE genotypes in 42 cases of AD patients, 40 cases of non-AD dementia patients, and 49 cases of age-matched controls. DNA from the target sequence on APOE was amplified by PCR from peripheral blood genomic DNA. PCR products were electrophoresed in a non-denaturing polyacrylamide gel and visualized by silver staining. We found that the epsilon4 allele had a significantly high frequency of occurrence in AD patients (33.3%) compared with age-matched controls (13.3%) (chi(2) = 10.43, p = 0.001) and non-AD dementia (10%) (chi(2) = 13.02, p<0.001) whereas the epsilon3 allele was of high frequency in non-AD dementia (90%) compared with age-matched controls (85.7%) and AD patients (66.7%). APOE epsilon4 homozygotes were found only in AD groups. On the other hand, the epsilon2 allele was found only in an age-matched control. This study confirmed that the APOE psilon4 allele is a risk factor in Thai AD subjects and that the PCR-SSCP method is a rapid and useful means of detecting the APOE genotype in AD.