Although the genetic polymorphism of the APOE has been associated with Alzheimer’s disease and cognitive function in elderly people, very few studies have been per- formed in subjects aged 100 and older. In a study of 47 Japanese centenarians, no significant difference was found in the frequency of the e4 allele between Alzheimer’s dis- ease and nondemented centenarians (22).

examinations, and laboratory tests. General physical exam- ination was performed by a doctor specializing in geriatric medicine, and cognitive function was assessed by a clinical psychologist. Fasting venous blood was obtained from each subject and collected into tubes containing ethylenediamine- tetraacetic acid [EDTA]. Genomic DNA was extracted from peripheral white blood cells using a Wizard Genomic DNA Purification kit (Promega, Madison, WI). The APOE genotyping was done with an INNO-LiPA Apo E Kit (Innogenetics N.V., Belgium) following the manufacturer’s instruction. The ACE gene polymorphism was identified as previously described (23) by polymerase chain reaction (PCR) assay with primers flanking the polymorphic region. PCR products of the two alleles of 490 and 190 bp were separated on 1.5% agarose gel and visualized by ethidium bromide staining. The number of alleles was estimated by a gene-counting method.

The purpose of this study was to investigate the dis- tributions of the ACE and APOE gene polymorphisms in Korean centenarians and to evaluate the association of these genes with dementia in such extreme old age.

M ETHODS

Subjects

A total of 103 centenarians (13 men and 90 women) were included in this study. They ranged in age from 100 to 115 years. The mean age 6 standard deviation (SD) was 102.4 6 2.6 years. The Korean Centenarian Study was begun in December 1999. Persons born in 1900 or earlier were identified from the national registry of centenarians of the Ministry of Health and Welfare. Fifty-eight centenarians were living in the Seoul metropolitan area and 11, 22, and 12 centenarians were recruited from Kyungsang, Chunra, and Cheju provinces, respectively. Our medical team obtained consent from each subject or close relatives and visited their homes. The ACE and APOE genotype of the control group was drawn from the data of individuals who visited the Health Promotion Center at Samsung Medical Center for periodic health examination. The control population for the ACE genotyping was 7232 apparently healthy adults, of mean age 48.5 6 9.6 years and ranged from age 20 to 85 years. There were 4100 men (mean age 48.6 6 9.6 years, range 23–81 years) and 3132 women (mean age 48.3 6 9.7 years, range 20–85 years). The control population for the APOE genotyping was 6435 apparently healthy adults, of mean age 50.7 6 7.9 years and age range from 30 to 79 years. There were 5008 men (mean age 50.6 6 7.9 years, age range 30–79 years) and 1427 women (mean age 51.1 6 8.1 years, age range 30–78 years).

Dementia status was appropriately assessed in 89 cen- tenarians (men 11, women 78) with the following Clinical Dementia Rating (CDR) scores (24): 0, no dementia; 0.5, dementia suspected; 1, mild dementia; 2, moderate dementia; and 3, severe dementia. Subjects were divided into two groups according to their dementia status. A CDR score of 0 or 0.5 was considered to indicate the absence of defini- tive dementia, while a score of 1, 2, or 3, the presence of dementia (25).

To compare the difference in frequency between the groups, the chi-square test was performed. A p value of less than .05 was considered to indicate a significant difference. All results are expressed as mean 6 SD. Statistical analysis was carried out using SAS (Statistical Application System, Version 6.10; SAS, Inc., Cary, NC).

R ESULTS

The frequencies of the genotypes and alleles of the ACE and APOE genes in Korean centenarians and control groups are compared in Tables 1 and 2. The genotype distributions

Centenarian subjects underwent medical examination, which consisted of an interview, physical and mental

100% -Ageay   Eee] a: =eee ae84 a3 895 eat ear  30-39an40-49(2897)  50-59(2270) fale102 a2  60-69(esa)     eee]72 6a8641 86867 6370-78 100-115(104) (103)jetme

Table 3. Dementia Status According to Clinical Dementia Rating in Centenarians

Number Men Women Dementia status CDR score 0 2 4 Without definitive dementia (n 5 34) 0.5 4 24 Mean CDR score .4 6 .2* 1 4 20 With dementia (n 5 55) 2 1 12 Mean CDR score 1.9 6 .9* 3 0 18

Notes: Dementia status was assessed with clinical dementia rating (CDR) scores: 0, no dementia; .5, dementia suspected; 1, mild dementia; 2, moderate dementia; and 3, severe dementia. Subjects were divided into two groups ac- cording to their dementia status. A CDR score of 0 or .5 indicated the ab- sence of definitive dementia, while a score of 1, 2, or 3 indicated the presence of dementia.

Figure 1. Distribution of apolipoprotein E alleles according to age in a Korean population. The frequency of the e4 allele gradually decreases after the eighth decade and tends to be lower in the centenarians. However, the e2 allele does not show any age-dependent change in its proportion.

*Mean 6 standard deviation p value ,.001 from t test.