Socio-demographic variation of dementia subtypes in china: Methodology and results of a prevalence study in Beijing, Chengdu, Shanghai, and Xian.

OBJECTIVE: To characterize sociodemographic variations in the prevalence of AD and VaD in China. METHODS: Data were collected in a 1997-1998, cross-sectional, door-to-door prevalence survey of 34,807 community residents ages > or =55 years in Beijing, Shanghai, Chengdu and Xian. Initial diagnoses of AD and VaD were assessed by clinicians using standardized protocols, according to the NINCDS-ADRDA and NINDS-AIREN criteria; diagnoses were confirmed after 6 months by repeating neuropsychological evaluations. Prevalence odds ratios were estimated in logistic models adjusting for survey design, age, and other sociodemographic factors. RESULTS: We identified 732 prevalent cases of AD and 295 cases of VaD. Adjusting for all sociodemographic factors concurrently, prevalence odds of AD and VaD were higher in northern versus southern China. Age trends for AD appeared different in western and eastern China. AD also showed an age-adjusted elevation among women and, in the fully adjusted model, a gender education interaction indicating a female preponderance in the highest education group. North-south variation for VaD was age-dependent. In the fully adjusted model, for AD, widowed had significantly higher prevalence odds; for VaD, widowed persons and minorities had significantly lower prevalence odds; professionals had statistically significant and borderline lower prevalence odds for both VaD and AD; sales-service occupations had significantly lower odds for AD only. CONCLUSION: We observed variations in prevalence for AD and VaD in different regions and demographic groups in China that persisted after controlling for potential confounding factors. Sociodemographic factors are probable surrogates for conditions such as lifestyle, environment, comorbidities, and life expectancy.

Association between angiotensin-converting enzyme gene polymorphism and Alzheimer's disease in a Chinese population.

Angiotensin-converting enzyme has shown altered activity in patients with neurological diseases. An insertion/deletion (I/D) polymorphism of the DCP1 gene encoding angiotensin-converting enzyme has been reported to be associated with the risk for Alzheimer's disease (AD), but ambiguous results have also been presented. We conducted a case-control study in a sample composed of 192 sporadic AD patients and 195 age- and sex-matched controls from Chinese Han population in Beijing and Xi'an districts to investigate the possible effect of the polymorphism. Our data revealed no association between the DCP1 polymorphism and AD risk in the total sample. There was no significant difference in the DCP1 allele or genotype frequencies between cases and controls when stratified by gender and APOE epsilon4 status. However, the D allele and D/D genotype were more frequent among AD patients between 66 and 70 years compared with controls (D allele: OR=2.8, 95% CI=1.5-5.2, p=0.001; D/D genotype: OR=5.9, 95% CI=1.7-19.9, p=0.002). Our results provided new proof that the DCP1 D allele was a probable risk factor for late-onset AD. Its role was independent and was limited to the population at a certain age.

Dementia subtypes in China: prevalence in Beijing, Xian, Shanghai, and Chengdu.

BACKGROUND: Prevalences of Alzheimer disease (AD) and vascular dementia (VaD) in China reportedly differ from those in Western countries. OBJECTIVE: To estimate prevalence of AD and VaD in 4 regions of China. DESIGN: Cross-sectional, population-based prevalence survey with a stratified, multistage cluster sampling design. SETTING: Rural (n = 99) and urbanized (n = 71) communities of Beijing, Xian, Shanghai, and Chengdu. PARTICIPANTS: A sample of 34 807 community residents (94% of those eligible) 55 years or older. MAIN OUTCOME MEASURES: Participants were screened with the Chinese Mini-Mental State Examination. Those who screened positive (n = 3950) underwent a standardized diagnostic workup. Screening sensitivity was assessed in a 3.3% random sample (n = 1008 of the 30 857 who passed the screening). Diagnoses of AD and VaD were made according to National Institute of Neurological and Communicative Diseases and Stroke-Alzheimer Disease and Related Disorders Association and National Institute of Neurological Disorders and Stroke-Association Internationale pour la Recherche et l'Enseignement en Neurosciences criteria, respectively. Final diagnoses were made after a 6-month confirmation interval. RESULTS: We identified 732 AD cases and 295 VaD cases. Prevalence in persons 65 years or older was 3.5% (95% confidence interval, 3.0%-3.9%) for AD and 1.1% (95% confidence interval, 0.9%-1.1%) for VaD. After post hoc correction for negative screening errors, prevalence increased to 4.8% for AD and remained at 1.1% for VaD. CONCLUSION: Prevalence of dementia subtypes in China is comparable with that in Western countries.

Parkinson's disease in China: prevalence in Beijing, Xian, and Shanghai.

A cross-sectional prevalence study of Parkinson's disease in China was undertaken in 1997-98. We assessed 29?454 residents aged > or =55 years from 79 rural and 58 urban communities in Beijing, Xian, and Shanghai, who were selected through stratified, multistage, cluster sampling. With a standardised diagnostic protocol, we identified 277 people with the disease. Prevalence of Parkinson's disease for those aged > or =65 years was 1.7% (95% CI 1.5-1.9). We estimate that 1.7 million people in China have the disease (aged > or =55 years). Our findings suggest that prevalence of Parkinson's disease in China is similar to that in developed countries.

Association between cathepsin D polymorphism and Alzheimer's disease in a Chinese Han population.

Cathepsin D (CTSD) is an intracellular aspartyl protease, which is active in the endosomal/lysosomal system. CTSD may play a role in Alzheimer's disease (AD) through cleaving the amyloid precursor protein into beta-amyloid peptide and degrading tau protein into fragments. A functional polymorphism in exon 2 of the cathepsin D gene (C-->T, Ala224Val) has recently been reported to increase the risk for AD in some of the Caucasian populations, with a significant overrepresentation of the T allele, but these reports have not been universally duplicated. We performed an association study between CTSD polymorphism and AD in 156 sporadic AD patients and 183 controls of Chinese Han ethnicity. Our data revealed that the distribution of CTSD genotypes and alleles was similar in patients and controls. No direct association was found between CTSD polymorphism and AD risk. There might be a weak synergistic interaction between CTSD T and APOEepsilon4 allele in increasing the risk for developing AD.

Association of alpha 2-macroglobulin polymorphisms and Alzheimer disease in Mainland Han Chinese.

This study used case-control method to investigate roles of two alpha 2-macroglobulin (A2M) polymorphisms, a 5-bp insertion/deletion (A2M-I/D) and an A-->G substitution (A2M-A/G), in the development of sporadic Alzheimer disease (AD) in Mainland Han Chinese. Our results showed a trend of lower D-carrying genotype frequency in APOE-epsilon 4 carrying AD patients than in corresponding control subjects (chi(2)=3.67, p=0.055). The ID/AA genotype frequency was lower in AD patients comparing with controls (chi(2)=4.04, p=0.044). In AD patients, the G-carrying genotype frequency was significantly higher in APOE-epsilon 4 carrier subgroup than in APOE-epsilon 4 non-carriers (chi(2)=7.38, OR=2.99, 95% CI: 1.33-6.71, p=0.007). These results indicated that A2M-D allele was probably a weak AD protective factor, and there was a possible interaction of APOE-epsilon 4 and A2M-G alleles to increase AD risk in Mainland Han Chinese.

[Apolipoprotein E gene polymorphisms and Alzheimer disease].

PCR-RFLP was used to investigate the distribution differences of apolipoprotein E (APOE) alleles and genotypes between sporadic Alzheimer disease (AD) patients (n = 160) and healthy control individuals (n = 195) in Chinese Han population. The results showed that the allelic frequencies of APOE epsilon 2, epsilon 3 and epsilon 4 were 0.056, 0.713 and 0.231 in AD group respectively, and 0.082, 0.844 and 0.074 in control group respectively. The frequency of epsilon 4 allele was significantly higher in AD cases than in control subjects and epsilon 4 allele was associated with AD by an odds ratio (OR) of 3.82 (chi 2 = 28.70, P < 0.001). The probability for APOE epsilon 4-carriers to suffer from AD after 65 years old was 5.38 times of that for APOE epsilon 4 non-carriers (chi 2 = 29.76, P < 0.001), suggesting that age might affect the interaction between APOE epsilon 4 and AD. In addition, our results showed that the distributions of APOE alleles and genotypes were comparable among mild, moderate and severe dementia patients (P > 0.05), suggesting that APOE gene polymorphism was not likely to contribute to dementia severity of AD patients. The frequency of APOE epsilon 4 genotype in female patients was higher than that in male patients(43.0% vs. 36.5%) and females carrying APOE epsilon 4 allele had higher OR value than corresponding males (4.3 vs. 3.3), but the differences were not statistically significant (P > 0.05). As to epsilon 2 allele, its frequency was significantly lower in male subgroup than in female subgroup of AD patients and also than in male subgroup of normal control (P < 0.05), suggesting that epsilon 2 allele was possibly an AD protective factor in Chinese male population.