Table 1. The characteristics of the study population.

	AD (n = 984)	HC (n = 1352)	P value
Age, years; mean±SD	75.15±6.08	75.50±6.49	0.185*
Gender, n (%)			0.074
Male	406 (41.3)	608 (45.0)
Female	578 (58.7)	744 (55.0)
MMSE score, mean±SD	11.99±6.20	28.49±1.09	<0.001
APOE ε4 status, n (%)			<0.001
APOE ε4 (+)	280 (28.5)	191 (14.1)
APOE ε4 (-)	704 (71.5)	1161 (85.9)

Abbreviations: AD, Alzheimer's disease; HC, healthy controls; MMSE, Mini-Mental State Examination; ApoE; apolipoprotein E; SD, standard deviation.

^*P value was calculated with the age of onset for late-onset AD and age at examination for control. Differences in the characteristics of age and MMSE score between the two groups were examined using Student's t test. Differences in gender and ApoE-ε4 frequency between AD patients and HC were assessed using the Pearson χ2 test.