Time since first cannabis use and 12-month prevalence of cannabis use disorder among youth and emerging adults in the United States

Aim This study estimated whether and how the 12-month prevalence of cannabis use disorder among US youth aged 12-17 and emerging adults aged 18-25 varied by time since first cannabis use. Design Repeated cross-sectional survey data from the 2015-17 National Surveys on Drug Use and Health (NSDUH). Setting United States. Participants A total of 101 000 NSDUH participants aged 12-25. Measurements Past 12-month cannabis use disorder was assessed using DSM-IV criteria. Findings Among youth, the life-time prevalence of cannabis use was 15.3% [95% confidence interval (CI) = 14.86-15.65%]. Among emerging adults, the life-time prevalence of cannabis use was 52.4% (95% CI = 51.77-53.01%). The adjusted 12-month prevalence of cannabis use disorder among youth with life-time cannabis use was 10.9% (95% CI = 9.24-12.75%) in the first year after starting cannabis use, 15.3% (95% CI = 13.68-17.12%) in the second year, 17.7% (95% CI = 15.55-19.97%) in the third year and 20.6% (95% CI = 18.23-23.17%) in the fourth year and beyond, which was consistently higher after the first year (linear trend only: P < 0.0001). The adjusted 12-month prevalence of cannabis use disorder among emerging adults with life-time use ranged from 5.6% (95% CI = 4.26-7.23%) in the first year after starting cannabis use, 7.7% (95% CI = 6.45-9.17%) in the second year and 9.1% (95% CI = 7.81-10.57%) in the third year to 10.5% (95% CI = 9.87%-11.12%) in the fourth year and beyond, which was consistently higher after the first year (linear trend only: P < 0.0001). Within each time-frame since first cannabis use, the adjusted 12-month prevalence of cannabis use disorder was higher among youth life-time users than their emerging adult counterparts. Conclusions Among youth and emerging adults in the United States, the prevalence of cannabis use disorder appears to increase with time since initiation of use and is higher among youth than among emerging adults during each examined time-frame.