Study: In the USA, problematic cannabis use declines among daily users

A study published last month in the journal Drug and Alcohol Dependence appears to show a decrease in the proportion of daily cannabis users who are diagnosed with cannabis use disorder (CUD, for cannabis use disorder).

According to the document, «The prevalence of cannabis use disorders decreased significantly among all age groups reporting daily or nearly daily cannabis use between 2002 and 2016. The prevalence of cannabis dependence, meanwhile, decreased among adolescents and young adults and remained stable only among adults aged 26 and older who reported using cannabis daily or almost daily.”

Recent studies have yielded mixed results on the prevalence of problematic cannabis use, a diagnosis that includes misuse and/or dependence, over the past two decades. Because people who use cannabis daily or nearly daily are at the highest risk for problematic use, researchers at the Mailman School of Public Health Researchers at Columbia University have worked to better understand the health of this group.

The study authors used data from national surveys on drug use and health for the period 2002–2016. The final sample, comprising 22,651 individuals, included participants aged 12 and older who reported having used cannabis on at least 300 days during the past year.

To measure problematic consumption of Cannabis, the authors used the criteria from the Diagnostic and Statistical Manual of Mental Disorders (4th edition, DSM-IV), such as:

• Having spent a significant amount of time over the course of a month obtaining, using, or dealing with the effects of cannabis
• The inability to set limits for oneself
• The inability to reduce one's cannabis use
• Recurring spending that prevents one from fulfilling one's obligations
• Continued use despite persistent or recurring social or interpersonal problems

Other factors considered in the study included whether participants felt they needed mental health treatment, whether a doctor had indicated that they had other health problems, and whether or not they had driven while under the influence of illicit drugs, with or without alcohol.

During the study period, the authors found that the prevalence of CUD decreased across their entire sample in all age groups: for adolescents aged 12 to 17, the rate had decreased by 26.8%; for those aged 18–25, by 29.7%; and for adults aged 26 and older, by 37.5%.

«Among those who had used cannabis daily or almost daily in the past year, the prevalence of cannabis abuse decreased across all age groups, with reductions observed for all individual cases of abuse among adolescents and young adults,» the study states. «The prevalence of cannabis dependence also decreased among adolescents and young adults, but not among adults aged 26 and older. Decreases in most DSM-IV criteria for dependence were observed among young adults, while decreases were observed in only a few adolescents and among older adults.»

Researchers offer several possible explanations for this decline in problematic use, including the impact of various legalization measures.

«First, the new national policy environment regarding cannabis—with 33 states having legalized medical use and 10 states permitting recreational use—may have played a role in reducing the stigma and perceived risks associated with cannabis use,», according to Silvia Martins, one of the study’s authors. «Second, increasing legalization may also be associated with changes in social attitudes, which reduces the number of conflicts with parents and friends over cannabis use.»

Consequently, according to the document, «this could explain reductions in the item »Continued use despite persistent or recurrent social or interpersonal problems,» which reflects difficulties interacting with others due to cannabis use.»

It is also possible that a «segment of the population that is generally healthier» may begin to use more cannabis due to legal access, which «may have diluted the prevalence of cannabis abuse/dependence over time.» They might be using «less potent» cannabis or smaller daily amounts, the researchers note. Furthermore, respondents are now less hesitant to admit in a federal survey that they frequently use cannabis.

Finally, Martins stated that the study’s findings «would contradict the prevailing assumption that the prevalence of DSM-IV-defined cannabis use disorder is stable or increasing among those who use cannabis regularly.».