Table 1.
Demographic and clinical characteristics of study participants
| Characteristics | Adolescent group (n = 111) | Adult group (n = 114) | ||||||
|---|---|---|---|---|---|---|---|---|
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|
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| FH−controls (n = 30) | FH+controls (n = 30) | FH−MA users (n = 26) | FH+MA users (n = 25) | FH− controls (n = 30) | FH+controls (n = 30) | FH− MA users (n = 27) | FH+MA users (n = 27) | |
| Demographics | ||||||||
| Age (years) | 18.0 ±1.4 | 18.1 ±1.0 | 18.1 ±1.4 | 18.0 ±1.3 | 41.2 ±5.5 | 41.8 ±6.3 | 41.3 ±4.1 | 41.8 ±6.8 |
| Male sex, no. (%) | 24 (80.0) | 24 (80.0) | 20 (76.9) | 20 (80.0) | 24 (80.0) | 24 (80.0) | 22 (81.5) | 22 (81.5) |
| Education (years) | 11.4 ±1.2 | 11.5 ±1.0 | 10.6 ±1.9 | 11.2 ±1.4 | 13.8 ±2.1 | 13.7 ±2.4 | 12.6 ±2.1* | 11.7 ±2.0a |
| Right handedness, no. (%) | 25 (83.3) | 26 (86.7) | 22 (84.6) | 22 (88.0) | 25 (83.3) | 26 (86.7) | 23 (85.2) | 24 (88.9) |
| Race/ethnicity, no. (%) | ||||||||
| East Asian | 30 (100) | 30 (100) | 26 (100) | 25 (100) | 30 (100) | 30 (100) | 27 (100) | 27 (100) |
| SES, no. (%) | ||||||||
| Low | 3 (10.0) | 4 (13.3) | 5 (19.2) | 2 (8.0) | 5 (16.7) | 5 (16.7) | 9 (33.3) | 9 (33.3) |
| Middle | 24 (80.0) | 24 (80.0) | 18 (69.2) | 19 (76.0) | 21 (70.0) | 20 (66.7) | 14 (51.9) | 12 (44.4) |
| High | 3 (10.0) | 2 (6.7) | 3 (11.5) | 4 (16.0) | 4 (13.3) | 5 (16.7) | 4 (14.8) | 6 (22.2) |
| Smoking, no. (%) | ||||||||
| Current smoker | 7 (23.3) | 6 (20.0) | 20 (76.9)a | 18 (72.0)a | 12 (40.0) | 12 (40.0) | 22 (81.5)a | 22 (81.5)a |
| Former smoker | 0 (0.0) | 0 (0.0) | 1 (3.9) | 2 (8.0) | 7 (23.3) | 11 (36.7) | 3 (11.1) | 1 (3.7) |
| Never smoked | 23 (76.7) | 24 (80.0) | 5 (19.2) | 5 (20.0) | 11 (36.7) | 7 (23.3) | 2 (7.4) | 4 (14.8) |
| Clinical characteristics | ||||||||
| Onset age of MA use (years) | NA | NA | 15.1 ±1.0 | 14.7 ±1.1 | NA | NA | 24.9 ±5.4 | 26.2 ±7.9 |
| Lifetime cumulative dose (g) | NA | NA | 105.5 ±92.4 | 131.8 ±96.1 | NA | NA | 381.4 ±304.8 | 375.9 ±303.8 |
| Duration of regular use (months)b | NA | NA | 24.0 ±14.5 | 26.1 ±14.0 | NA | NA | 78.1 ±37.3 | 88.1 ±48.4 |
| Route of MA administration, no. (%) | ||||||||
| Intravenous injection | NA | NA | 17 (65.4) | 16 (64.0) | NA | NA | 26 (96.3) | 24 (88.9) |
| Smoking | 7 (26.9) | 9 (36.0) | 1 (3.7) | 3 (11.1) | ||||
| Oral ingestion | 2 (7.7) | 0 (0.0) | 0 (0.0) | 0 (0.0) | ||||
| Subjects reported ever having used cannabis, no. (%)c | 0 (0.0) | 0 (0.0) | 8 (30.8) | 7 (28.0) | 0 (0.0) | 0 (0.0) | 10 (37.0) | 13 (48.2) |
| Subjects having a past history of alcohol abuse, no. (%)d | 0 (0.0) | 0 (0.0) | 0 (0.0) | 2 (8.0) | 0 (0.0) | 0 (0.0) | 2 (7.4) | 2 (7.4) |
| Weekly alcohol consumption-standard drinks | 1.52 (2.56) | 2.20 (2.98) | 3.26 (3.78)* | 5.20 (5.24)a | 4.40 (5.36) | 4.41 (5.75) | 9.28 (9.13)* | 9.73 (9.91)* |
| SDS—total sores | NA | NA | 6.00 (3.64) | 5.76 (3.57) | NA | NA | 7.30 (3.23) | 7.00 (2.20) |
| AWQ—total sores | NA | NA | 9.73 (7.83) | 10.36 (8.67) | NA | NA | 14.89 (8.49) | 13.15 (6.66) |
| VASe—scores | NA | NA | 3.42 (1.06) | 3.32 (1.35) | NA | NA | 3.70 (1.38) | 3.48 (1.12) |
| ACQf—total sores | NA | NA | 114.3 (33.7) | 117.1 (38.1) | NA | NA | 127.4 (39.4) | 125.4 (36.1) |
| Stroop interferencea | 0.394 (0.155) | 0.451 (0.217) | 0.439 (0.202) | 0.589 (0.313)a | 0.473 (0.1 90) | 0.490 (0.214) | 0.546 (0.210) | 0.584 (0.303) |
Means and standard deviation values are denoted as mean ±s.d. FH − stands for a negative family history of drug-related problems. FH+ stands for a positive family history of drug-related problems. A positive family history was defined as having (i) at least one parent who had alcohol or drug dependence and (ii) one or more first- or second-degree relatives with alcohol or drug abuse.
Significant at P<0.05 and significant at **P<0.01 when compared with FH − controls in the respective adolescent or adult group using the Student’s t-test for continuous variables and the χ2 tests or the Fisher’s exact tests for categorical variables.
Abbreviations: ACQ, Amphetamine Craving Questionnaire; AWQ, Amphetamine Withdrawal Questionnaire; MA, methamphetamine; NA, not applicable; SDS, Severity of Dependence Scale; SES, socioeconomic status; VAS, visual analog scale.
Stroop interference was calculated by subtracting time per item of Color task from time per item of Color-Word task. A lower score means less susceptibility to interference thus higher task performance.
Duration was calculated by summing up the time when MA was used more frequently than weekly.
None of MA users had a history of lifetime and current cannabis dependence or abuse.
MA users had a past history of alcohol abuse but did not have a current one.
Subjective craving for MA was measured using a visual analog scale that ranges from 0 to 10.
A modified version of the Cocaine Craving Questionnaire, which substitutes the word ‘MA’ for ‘cocaine,’ was used.