There were statistically significant differences in mean age and the distributions of sex, education, smoking, alcohol intake, ischemic heart disease, and stroke among the three groups of people with SCD, MCI, and normal cognition (P < 0.05), but the three groups did not differ significantly in the distributions of occupation, physical exercise, body mass index (BMI), hypertension, diabetes, hyperlipidemia, and APOE ε4 status (Table 1). The gene discussed is APOE; the disease is Schnyder corneal dystrophy.