Over the last few decades, there has been an increase in cannabis potency and use in the United States. Researchers used data from the Michigan Longitudinal Study to determine whether higher average potency levels at initiation of cannabis use were associated with progression to regular use, daily use, and cannabis use disorder (CUD) symptoms. Cannabis potency was obtained from analysis of cannabis confiscated by the US Drug Enforcement Agency and reported as an annual average.
- The average potency of cannabis (%THC) increased from 4% to 12% between 1994 and 2012.
- Potency was not associated with progression to first use or to regular cannabis use.
- After adjusting for sex, regular use, and birth year, potency was associated with progression to first CUD symptoms (hazard ratio [HR], 1.4). For every 1% increase in cannabis potency, there was a 1.4 times increased risk of progression to CUD symptom onset.
- Progression to first CUD symptoms was associated with regular cannabis use (HR, 4.1) and daily cannabis use (HR, 3.14).
Comments: This study suggests that cannabis potency may be associated with CUD symptom progression. Study limitations included the use of a national measure of potency, which cannot account for local or individual cannabis potency differences. Nonetheless, this should raise concerns about potential harms. The increasing legalization of cannabis in the US should be viewed as an opportunity to potentially regulate potency to limit harms while this is studied further.
Jarratt Pytell, MD† & Darius A. Rastegar, MD
† Contributing editorial intern and Addiction Medicine Fellow, Johns Hopkins Medicine
Reference: Arterberry BJ, Treloar Padovano H, Foster KT, et al. Higher average potency across the United States is associated with progression to first cannabis use disorder symptom. Drug Alcohol Depend. 2019;195:186–192.