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. Author manuscript; available in PMC: 2017 Apr 1.
Published in final edited form as: Drug Alcohol Depend. 2016 Feb 12;161:163–170. doi: 10.1016/j.drugalcdep.2016.01.029

Table 1.

Demographic Characteristics of Research Participants.

All participants (n = 196) Participants in ASI (n =33) Participants in PET scan and ASI (n = 20)
Control group (n = 102) MA group (n = 94) Group difference: p-value Control group (n = 20) MA group (n = 27) Group difference: p-value MA group MA group
Age (years) 33.7 ± 8.94 34.2 ± 9.70 0.751 a 36.3 ± 7.09 31.5 ± 8.65 0.048 a 33.2 ± 9.62 30.0 ± 8.10
Sex (Male/ Female) 48 / 54 56 / 38 0.079 b 10 / 10 14 / 13 0.900 b 20 / 13 11 / 9
Ethnicity 45 Caucasian, 31 Hispanic, 13 African American, 5 Asian, 8 other 45 Caucasian, 28 Hispanic, 7 African American, 3 Asian, 11 other 0.264 b 12 Caucasian, 3 Hispanic, 1 African American, 2 Asian, 2 other 16 Caucasian, 7 Hispanic, 2 Asian, 2 other 0.604 b 15 Caucasian, 11 Hispanic, 2 Asian, 5 other 9 Caucasian, 7 Hispanic, 2 Asian, 2 other
Education (years) 12.9 ± 1.91 12.1 ± 1.67 0.001 a 13.9 ± 2.03 12.3 ± 1.69 0.005 a 12.1 ± 2.12 11.7 ± 2.17
Tobacco Smokers 32 76 < 0.001 b 11 23 0.045 b 29 17
Regular marijuana userc 12 41 < 0.001 b 0 12 < 0.001 b 15 10
Self-report of methamphetamine use
Days abstinent before administration of DERS - 4.5 ± 3.37 - 4.0 ± 2.59 4.6 ± 3.62 4.1 ± 2.69
Days abstinent before administration of PET scan - - 6.9 ± 2.24 7.0 ± 2.45
Days of use in month before testing - 21.2 ± 8.46 - 21.3 ± 8.06 21.9 ± 7.73 22.7 ± 7.39
Age of first use (years) - 21.0 ± 6.77 - 21.4 ± 6.97 19.0 ± 5.50 19.5 ± 5.00
a

Group difference evaluated by Student’s t-test.

b

Group difference in likelihood evaluated by Pearson’s Chi-square test.

c

Used marijuana within 1 month of enrolling in the study.

Data is shown as mean ± SD.

MA: methamphetamine.