Depressive symptoms. The depression items from the Physicians Health Questionnaire (PHQ-9; Spitzer, Kroenke, & Williams, 1999), with the suicide item omitted, yielded an 8-item scale of current depressive symptoms (α = .84). Alcohol problem severity. Alcohol Use Disorders Identification Test (AUDIT; Bohn, Babor, & Kranzler, 1997) scores provided a continuous assessment of the severity of alcohol-related problems in the past year (α = .83). Primary substance of use. The item “Which drug, including alcohol, is your primary substance of use?” was asked to create three mutually exclusive categories of primary substance: alcohol, cocaine, and other. Supporting the item’s validity, primary substance of use correlated highly with items that ask which substance was used “most frequently (r= .79, p < .001)” and “caused the most problems” (r= .68, p < .001). Breadth of drug use. Using a list of drugs, participants reported their frequency of use of these substances on a 6-point range from “never” to “(nearly) every day.” The number of categories of substances used weekly or more were added to create a continuous measure of the breadth of drug
