At baseline, lifetime patterns of substance use are assessed in detail. This interview was developed in order to comprehensively measure substances that may lead to substance use disorders, or neurocognitive, psychiatric or health consequences in youth. The lifetime interview (created by first author based on a previously published lifetime use interview (Lisdahl and Price, 2012)) assesses whether they ever used each drug. If they used a substance, then follow-up questions are given to assess 1) age of first use, 2) age of first regular use (defined at baseline as at least weekly use for 6 months), 3) lifetime total quantity in standard units, 4) lifetime maximum (max) dose in standard units, and 5) last date of use (to measure length of abstinence). For any drug used in the past 6 months, a detailed Timeline Followback interview is also administered (see below for details). Questions are only administered if the youth has heard of each substance.
