Table 1.
Demographic Characteristics of the Twin Samples.
| Number of twin pairs | Age | ||||||
|---|---|---|---|---|---|---|---|
| Study | N | % female |
MZ (M/F) |
SSDZ (M/F) |
OSDZ | M (SD) | Range |
| GENDER | 498 | 50 | 0/0 | 0/0 | 249 | 74.51 (2.63) | 69.7–80.7 |
| LSADT | 4,731 | 58.93 | 175/276 | 246/415 | 21 | 77.26 (5.65) | 70–102 |
| MADT | 4,314 | 49.05 | 335/329 | 312/183 | 617 | 56.43 (6.33) | 45–68 |
| MIDUS | 1,762 | 55.79 | 158/181 | 108/183 | 218 | 45.01 (12.06) | 25–75 |
| MTSADA | 1,237 | 59.4 | 103/203 | 111/135 | 0 | 58.18 (11.21) | 25.5–92 |
| OCTO-Twin | 702 | 66.67 | 56/93 | 61/141 | 0 | 83.58 (3.17) | 79.4–97.9 |
| SATSA | 1,914 | 58.52 | 116/145 | 177/291 | 0 | 60.12 (13.88) | 26.1–92.9 |
| TOSS | 1,739 | 62.97 | 121/254 | 196/282 | 0 | 44.86 (4.89) | 32–60 |
| VETSA | 1,233 | 0 | 348/0 | 262/0 | 0 | 55.43 (2.49) | 51–60 |
| Total | 18,130 | 52.70 | 1,412/1,481 | 1,473/1,738 | 1,105 | 61.64 (14.67) | 25–102 |
Note. N = number of individual twins; MZ = monozygotic; SSDZ = same-sex dizygotic; OSDZ = opposite-sex dizygotic; GENDER = Aging in Women and Men: A Longitudinal Study of Gender Differences in Health Behavior and Health Among Elderly; LSADT = Longitudinal Study of Aging Danish Twins; MADT = Middle-Aged Danish Twins; MIDUS = Midlife in the United States; MTSADA = Minnesota Twin Study of Adult Development and Aging; OCTO-Twin = origins of variance in the oldest-old; SATSA = Swedish Adoption Twin Study of Aging; TOSS = Twin and Offspring Study in Sweden; VETSA = Vietnam Era Twin Study of Aging.