Clinical significance was addressed with two variables. One was significant distress or impairment due to the cannabis withdrawal symptoms in social, occupational, or other important areas. The second was use of another substance to avoid or alleviate the withdrawal symptoms. We investigated the relationship of cannabis withdrawal to demographic characteristics (gender, age, race/ethnicity, marital status and education) and to psychiatric and drug use history, including lifetime primary diagnoses of major depressive, generalized anxiety and panic disorders, since these share symptoms with cannabis withdrawal. Substance-induced disorders were excluded. We also included personality disorders assessed in the NESARC (avoidant, dependent, obsessive-compulsive, paranoid, schizoid, histrionic and antisocial). The reliability and validity of these diagnoses are fair to excellent, 31, 36–38 comparing favorably to other research diagnostic interviews. Cannabis history variables included duration of period of heaviest use (≥1 one year vs. others), usual number of joints smoked during period of heaviest use (≤1 vs. 2 [the median] or more), and age at onset of use <16 years. Period of heaviest use was dichotomized as <52 weeks (1st quartile) vs. ≥52 weeks. Additional predictors included family history of drug problems (parent or sibling positive).
