Table 1. Characteristics of study groups.
| Characteristics | AD cases | Controls | Total | P value |
|---|---|---|---|---|
| N | 978 | 1,340 | 2,318 | – |
| Age at examination (mean ± SD), years | 79.830±6.70 | 75.500±6.50 | – | – |
| Age onset (mean ± SD), years | 75.141±6.07 | – | – | 0.181* |
| Sex (%) | 0.096 | |||
| Male | 404 (41.31) | 600 (44.78) | 1,004 (43.31) | |
| Female | 574 (58.69) | 740 (55.22) | 1,314 (56.69) | |
| MMSE (mean ± SD) | 12.016±6.19 | 28.478±1.09 | – | <0.001 |
| APOE ε4 carrier (%) | 278 (28.43) | 187 (13.95) | 465 (20.06) | <0.001 |
| APOE ε4 no carrier (%) | 700 (71.57) | 1,153 (86.04) | 1,853 (79.94) | – |
*, P value was calculated with the age of onset for late-onset AD cases and age at examination for control subjects. Differences in the characteristics of age and MMSE score between the two groups were examined using the Student’s t-test. Differences in sex and genotype frequencies of apolipoprotein E (APOE) between AD cases and control subjects were assessed using the Pearson χ2 test. Distributions of the APOE polymorphisms were in Hardy-Weinberg equilibrium in both patients and control subjects. AD, Alzheimer’s disease; SD, standard deviation; MMSE, Mini-Mental State Examination.