Table 1.

Participant characteristics

Sociodemographic variables	Mean (SD) or percentage
Gender
Male	74.2%
Female	25.8%
Ethnicity
Caucasian	50.9%
African-American	45.4%
Hispanic, Asian, or multiethnic	3.7%
Age (years)	42.1 (11.1)
Education	12.2 ( 1.6)
Heroin use characteristics
Age of initial heroin use (years)	25.4 ( 8.3)
Age of regular heroin use (years)	26.9 ( 8.6)
Lifetime duration of regular heroin use (years)	14.9 (11.1)
Past-month heroin use (days)	28.1 ( 4.9)
Lifetime attempts to quit heroin use	9.8 (19.5)
Lifetime injection use (% yes)	67.5%
Lifetime heroin-use consequences	7.8 ( 4.4)
Study variables
BIS-11 Attentional impulsivity	15.6 ( 3.3)
BIS-11 Motor impulsivity	23.8 ( 4.0)
BIS-11 Non-planning impulsivity	28.8 ( 4.9)
BDI-II depression	15.3 (10.2)
DASS Stress	5.1 ( 4.0)
Perception of life events	18.1 (34.9)