Table 2.
Distribution of population characteristics by early psychoactive drug usea among Add Health participants, baseline in 1994, follow-up in 1996–2008.
| Drug use at respective wave of data collection |
|||||||||
|---|---|---|---|---|---|---|---|---|---|
| Wave 2 |
Wave 3 |
Wave 4 |
|||||||
| Marijuana |
Illegal drugsb |
Cocaine |
Marijuana |
Illegal drugsb |
Cocaine |
Marijuana |
Illegal drugsb |
Cocaine |
|
| Mean %†† | Mean %†† | Mean%†† | Mean %†† | Mean %†† | Mean %†† | Mean %†† | Mean %†† | Mean %†† | |
| Demographics | |||||||||
| Mean age, years | 16.6c 30.25 | 16.7c 6.2 | 16.9c 1.9 | 22.0c 66.9 | 21.8c 54.0 | 22.0c 52.0 | 28.6c 47.9 | 28.6c 18.1 | 28.6c 18.8 |
| Age of baseline drug use | |||||||||
| Tobacco (n = 2887; %††) | |||||||||
| Wave 1 non-users | 14.1 (408) | 8.3 (55) | 12.9 (19) | 17.9 (338) | 23.9 (72) | 12.8 (39) | 18.7 (253) | 15.3 (195) | 14.0 (187) |
| ≤ 10 | 18.2 (411) | 18.9 (93) | 10.7 (21) | 16.1 (271) | 9.5 (67) | 22.5 (56) | 18.8 (261) | 17.2 (234) | 17.3 (237) |
| 11–15 | 59.2 (1792) | 66.0 (440) | 71.8 (151) | 67.6 (1232) | 54.0 (264) | 60.2 (275) | 57.1 (935) | 63.5 (972) | 64.4 (988) |
| 16–18 | 9.8 (96) | 6.7 (34) | 3.9 (5) | 7.2 (146) | 3.6 (31) | 4.5 (26) | 5.3 (123) | 3.8 (89) | 4.3 (92) |
| Alcohol (n = 2129; %††) | |||||||||
| ≤ 10 | 13.3 (273) | 13.2 (69) | 15.1 (34) | 11.8 (160) | 5.1 (34) | 10.9 (47) | 10.9 (115) | 10.8 (115) | 11.6 (122) |
| 11–15 | 78.0 (1628) | 80.4 (395) | 83.0 (126) | 81.6 (1049) | 89.7 (241) | 81.0 (224) | 81.0 (814) | 84.5 (858) | 82.9 (840) |
| 16–19 | 8.7 (228) | 6.4 (38) | 1.9 (3) | 6.5 (110) | 5.3 (34) | 8.1 (25) | 11.0 (115) | 4.7 (80) | 5.5 (82) |
| Marijuana (n = 3330;%††) | |||||||||
| Wave 1 Non-users | 30.5 (834) | 23.5 (112) | 13.0 (24) | 43.8 (818) | 42.5 (163) | 34.1 (127) | 37.7 (608) | 38.7 (558) | 37.3 (525) |
| ≤ 10 | 3.4 (108) | 3.5 (38) | 8.5 (22) | 3.2 (78) | 3.1 (27) | 2.5 (27) | 3.2 (52) | 3.4 (49) | 3.7 (49) |
| 11–15 | 53.8 (1534) | 62.5 (413) | 63.5 (130) | 44.8 (893) | 51.1 (209) | 55.3 (197) | 47.6 (714) | 47.4 (717) | 47.8 (757) |
| 16–18 | 12.3 (396) | 10.5 (59) | 15.0 (17) | 8.2 (196) | 3.3 (34) | 8.1 (44) | 11.4 (195) | 10.5 (161) | 11.2 (169) |
| Any illegal drugs (3326; %††) | |||||||||
| Non-users | 79.6 (2632) | 53.8 (323) | 58.8 (106) | 83.9 (2079) | 86.0 (435) | 79.5 (346) | 86.4 (1710) | 77.2 (1364) | 80.8 (1388) |
| ≤ 15 | 15.8 (523) | 32.8 (263) | 34.1 (80) | 12.7 (313) | 11.8 (101) | 17.8 (99) | 11.0 (219) | 17.8 (347) | 14.4 (311) |
| 16–18 | 4.6 (51) | 13.4 (98) | 7.1 (19) | 3.4 (108) | 2.2 (16) | 2.7 (15) | 2.6 (67) | 5.0 (105) | 4.8 (98) |
| Age of cocaine use (n = 3330; %††) | |||||||||
| Wave 1 Non-users | 91.7 (2985) | 80.0 (513) | 72.6 (124) | 92.0 (2290) | 92.4 (487) | 89.9 (400) | 93.3 (1870) | 89.0 (1614) | 86.9 (1557) |
| ≤ 15 | 5.9 (236) | 12.3 (125) | 17.1 (60) | 6.3 (175) | 5.9 (50) | 7.7 (44) | 5.0 (101) | 8.2 (148) | 9.1 (163) |
| 16–18 | 2.4 (109) | 7.7 (45) | 10.3 (23) | 1.7 (48) | 1.8 (15) | 2.4 (17) | 1.7 (33) | 2.8 (52) | 4.0 (72) |
| Sex (n = 3359; %††) | |||||||||
| Male | 38.6 (1260) | 34.6 (254) | 38.6 (97) | 46.7 (1106) | 48.9 (261) | 53.9 (235) | 51.9 (1024) | 48.5 (888) | 50.8 (870) |
| Female | 61.4 (2099) | 65.4 (435) | 61.4 (114) | 53.3 (1425) | 51.1 (295) | 46.1 (229) | 48.1 (1004) | 51.5 (947) | 49.2 (939) |
| Race (n = 3357;%††) | |||||||||
| Black | 17.1 (753) | 1.9 (24) | 2.3 (17) | 19.4 (72) | 8.7 (120) | 5.1 (54) | 20.6 (593) | 5.6 (153) | 4.4 (154) |
| White | 60.9 (1683) | 82.4 (487) | 68.7 (121) | 64.8 (360) | 72.2 (54) | 77.7 (290) | 62.3 (993) | 77.7 (1273) | 72.1 (1161) |
| Hispanics | 22.0 (921) | 15.7 (178) | 29.0 (73) | 15.8 (124) | 19.1 (120) | 17.2 (120) | 17.1 (439) | 16.7 (407) | 23.5 (492) |
| CES-D (2709; %††) | |||||||||
| < 24 | 41.6 (1126) | 42.4 (233) | 49.0 (72) | 44.9 (1355) | 47.3 (300) | 43.5 (252) | 41.7 (1201) | 45.5 (1141) | 44.3 (1094) |
| ≥ 24 | 58.4 (1583) | 57.6 (317) | 51.0 (75) | 55.1 (1311) | 52.7 (278) | 56.5 (225) | 58.3 (1127) | 54.5 (996) | 55.7 (974) |
| Access to mental health (3359; %††) | |||||||||
| Wave 1 non-users | 80.0 (2722) | 74.4 (532) | 65.4 (136) | 83.0 (2096) | 83.1 (445) | 83.0 (380) | 83.8 (1707) | 79.3 (1447) | 81.3 (1436) |
| Users | 20.0 (637) | 25.6 (157) | 34.6 (75) | 17.0 (435) | 16.9 (111) | 17.0 (84) | 16.2 (321) | 20.7 (388) | 18.7 (371) |
Add Health = National Longitudinal of Adolescent to Adult Health; CES-D = The Center for Epidemiologic Studies Depression Scale.
n = Sample distribution of main variables and other covariates. Figure in parentheses refers to unweighted distribution and %†† describes weighted per cent distribution.
Significant differences between groups at α = 0.05, tested using χ2 tests for categorical variables and analysis of variance for continuous variables.
Per cent are weighted to account for sampling weights.
Categories shown above are not mutually exclusive.
Illegal drugs include any type of illicit drug such as LSD, PCP, ecstasy, mushrooms, speed, ice, heroin or pills without a doctor's prescription.
Mean age of respective drug used across different wave of data collection.