As the potency of weed has increased, so too have addictions

Story at a glance

  • Use of higher-potency cannabis products is associated with increased risks of addiction and psychosis, according to new research.

  • Previously, advocates have called for mental health warning labels for products sold in California.

  • Authors of the new research suggest policy makers carefully assess THC levels in products on the market.

New research published in The Lancet details an association between high cannabis potency – or concentration of THC– and an increased risk of psychosis and cannabis use disorder (CUD). 

“THC concentrations in cannabis have increased globally in recent decades,” authors wrote. “In the USA and Europe, the concentration of THC has more than doubled over the past 10 years, and new legal markets have facilitated the rapid development of cannabis products with higher potencies than earlier products, such as concentrated extracts.” 

THC is the psychoactive component in cannabis and its effects are dose-dependent. In the past, researchers have proposed a standardized unit of 5 mg of THC for all cannabis products. Low-potency was classified as between 5 mg and 10 mg of THC per product in the current review. 

Around three in 10 marijuana users in the United States currently have marijuana use disorder, Centers for Disease Control and Prevention data show.

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As of May, a total of 19 states, Washington, D.C., and Guam have legalized marijuana, while a bill aimed at decriminalizing the substance at the federal level was passed by the Democratic-majority House of Representatives in April.

Increasing state tax revenue and expunging prior criminal convictions are just a couple of the arguments proponents make in favor of decriminalization or legalization.

But several regulation concerns have been raised around these efforts, including by some who advocate for mental health warnings on product labels due to the potential risk of developing psychiatric disorders.

“Policy makers should carefully consider cannabis potency when regulating cannabis in legal markets, such as through limits or taxes based on THC concentration,” researchers wrote. 

To carry out their research, investigators assessed 20 studies comparing outcomes of high-potency cannabis users and low-potency users. Eight of the included studies focused on psychosis; eight on anxiety; seven on depression; and the remainder on CUD, they wrote. 

A total of 119,581 participants were included in the review. One study revealed those who used high potency cannabis daily were five times more likely to be diagnosed with a psychotic disorder compared with never-users. 

The same study found “daily use of lower potency cannabis was not associated with risk of psychotic disorder compared with people who never used cannabis.” 

The research marks the first review of its kind to take a wide look at addiction and mental health risks associated with highly potent cannabis use. 

“The findings support recommendations to discourage the use of higher potency cannabis products for low risk use. This recommendation should be incorporated into education tools and in the management of cannabis use in clinical settings,” authors concluded.