Table 1. The characteristics of the study population.

Characteristic	Patients with AD (n = 984)	Control subjects (n = 1354)	P value	OR (95% CI)
Age at examination, years; mean ± SD	79.81±6.71	75.50 ± 6.49	0.186*
Age at onset, years; mean ± SD	75.15 ± 6.08
Gender, n (%)
Male	406 (41.26%)	610 (45.05%)	0.068
Female	578 (58.74%)	744 (54.95%)
MMSE score, mean±SD	11.99 ± 6.20	28.49 ± 1.09	<0.001
APOE ε4 status, n (%)
APOE ε4 (+)	280 (28.46%)	191(14.11%)	<0.001	2.422 (1.970-2.977)
APOE ε4 (−)	704 (71.54%)	1163 (85.89%)

Abbreviations: AD, Alzheimer disease; APOE, apolipoprotein E; CI, confidence interval; MMSE, Mini Mental State Examination; OR, odds ratio; SD, standard deviation.

^*P value was calculated with the age of onset for late-onset AD and age at examination for control subjects. APOE ε4 (+) refers to subject carrying at least one APOE ε4 allele; APOE ε4 (−) refers to subject carrying no APOE ε4 allele. Differences in the characteristics of age and MMSE score between the two groups were assessed using the Student's t test. Differences in gender and APOE ε4 status between AD patients and control subjects were estimated using the Chi-square test.