Frequent cannabis users comprised 6.58% (N=2,613) of the NESARC. Most used cannabis 5–7 days a week during heaviest use (Table 1). Over half (57.2%) were diagnosed with DSM-IV cannabis abuse, while 16.2% were diagnosed with DSM-IV cannabis dependence (≥3 of 6 dependence criteria, not including withdrawal). Mean age of first cannabis use was 16.3 (range, 5–53), and total mean years from first to most recent use of cannabis was 12.5 (range, <1–53 years). Mean period of heaviest use was 5.2 years. Over two-thirds smoked >1 joint/day on days they smoked during their period of heaviest use; mean joints smoked/day was 3.9 (s.e., 0.1). About one-fifth had primary major depression, 8.8% had generalized anxiety disorder, 12.6% had panic disorder and 39.4% had personality disorders.
