Table 1.
Characteristics of the sample
| Characteristic | COGEND | COGA | FSCD | Total |
|---|---|---|---|---|
| Sample size (N) | 2575 | 1347 | 1170 | 5092 |
| Sex, N (%) | ||||
| Males | 978 (38.0%) | 713 (52.9%) | 581 (49.7%) | 2319 (44.8%) |
| Females | 1597 (62.0%) | 634 (47.1%) | 589 (50.3%) | 2852 (55.2%) |
| Age, years | ||||
| Mean ± SD | 36.6 ± 5.5 | 42.9 ± 10.3 | 37.0 ± 8.8 | 38.4 ± 8.3 |
| Range | 23 – 47 | 18 – 77 | 18 – 60 | 18 – 77 |
| Ancestry, n (%) | ||||
| European-American | 1899 (73.7%) | 974 (72.3%) | 558 (47.7%) | 3498 (67.6%) |
| African-American | 676 (26.3%) | 373 (27.7%) | 612 (52.3%) | 1673 (32.4%) |
| Diagnoses, n (%) | ||||
| Nicotine dependence | 1423 (55.3%) | 634 (47.1%) | 448 (38.3%) | 2505 (49.2%) |
| Alcohol dependence | 574 (22.3%) | 855 (63.5%) | 548 (46.8%) | 1977 (38.8%) |
| Cocaine dependence | 209 (8.1%) | 384 (28.5%) | 555 (47.4%) | 1148 (22.6%) |
| Marijuana dependence | 295 (11.5%) | 289 (21.5%) | 300 (25.6%) | 884 (17.4%) |
COGEND: Collaborative Genetic Study of Nicotine Dependence
COGA: Collaborative Study on the Genetics of Alcoholism
FSCD: Family Study of Cocaine Dependence