Table 1: Sample characteristics ( pairs).

Cases ()Controls ()

Age (years)1 (65–92) (65–92)
Women89 (56.7)82 (52.2)
Men68 (43.3)75 (47.8)
Education (years) (2–16) (0–16)
Physical activity2 (0–3) (0–3)
Zygotic status
 Monozygotic39 (24.8)
 Same-sex dizygotic67 (42.7)
 Opposite sex dizygotic49 (31.2)
 Indeterminate2 (1.3)
Clinical diagnoses
 Dementia104 (66.2)
 Cognitive impairment 53 (33.8)
 Cognitively intact157 (100)

Data are n (%) or means ± SD (range).
1Mean age excludes pairs where control was not assessed in person due to death ( pairs).
2Physical activity was assessed using a 0–3 scale, where 0 is no activity and 3 is frequent activity.