Table 5.
Prevalence of early substance involvement (by age 15) in European ancestry twins from intact and separated families, by quintile of predicted probability of parental separation.
| Predicted Probability of Parental Separation |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 0-20%ile | 21-40%ile | 41-60%ile | 61-80%ile | >80%ile | ||||||
| Intact (n = 313) | Separated (n = 35) | Intact (n = 285) | Separated (n = 62) | Intact (n = 227) | Separated (n = 109) | Intact (n = 165) | Separated (n = 214) | Intact (n = 81) | Separated (n = 284) | |
| Alcohol use, n (%) | 67 (21) | 11 (31)ns | 62 (22) | 26 (42) | 59 (26) | 40 (37)† | 61 (37) | 42 (20) | 14 (17) | 119 (43) |
| Alcohol Intoxication, n (%) | 24 (8) | 5 (14)ns | 17 (6) | 16 (26) | 18 (8) | 15 (14)ns | 14 (7) | 30 (18) | 3 (4) | 59 (21) |
| Cigarette use, n (%) | 78 (25) | 17 (49) | 103 (36) | 37 (60) | 95 (42) | 65 (60) | 87 (41) | 101 (61) | 51 (63) | 191 (68)ns |
| Regular smoking, n (%) | 17 (6) | 5 (15)ns | 24 (9) | 14 (23) | 22 (10) | 16 (15)ns | 22 (10) | 29 (18)† | 13 (16) | 76 (27)† |
| Cannabis use, n (%) | 12 (4) | 4 (12)ns | 11 (4) | 13 (22) | 12 (5) | 11 (10)ns | 13 (6) | 19 (12)ns | 5 (6) | 53 (19) |
| Other illicit drug use, n (%) | 6 (2) | 1 (3)ns | 0 (0) | 4 (7) | 1 (< 1) | 4 (4)† | 2 (1) | 10 (6) | 2 (3) | 10 (4)ns |
Note. Within quintile, intact and separated families differ significantly at p < .05, unless otherwise noted
†
p < 0.10
ns
p ≥ 0.10.
Because of imperfect matching on paternal alcoholism in the highest quintile, logistic regression analyses were conducted predicting each substance use variable from parental separation, unadjusted and adjusted for paternal alcoholism, with comparable effects of parental separation observed across all substance use variables.