Tags: Cannabis; Legalization; Psychosis;

 

Thumbnail: This viewpoint, written by psychiatrists, addresses the public health concerns of cannabis use as related to the risk of developing psychosis. Summarizing reports from across the field and taking into account several important factors, the authors conclude that there is a real concern that legalizing cannabis will increase the risk of psychosis across the general population, and suggest that governments should consider preventative or monitoring measures to minimize this.

 

The problem: There is a global trend toward legalizing cannabis use and commercializing its sale. As cannabis use has been linked to some psychiatric risks, psychiatrists have played a prominent role in policy discussions in many countries, however this has not necessarily been the case in the US.

 

The study: This study provides a perspective from psychiatrists on current and anticipated impacts of the changing cannabis policies in the US. This study reviews publications across the field and consolidates the growing evidence that there is a link between cannabis use and the development of psychosis. Factors including cannabis potency, frequency of use, and genetic predisposition are referenced for the role they play in contributing to the development of psychosis. The authors also take into account the impact that increased legalization, availability and commercialization of cannabis will have on this psychiatric risk, and make recommendations on how policy could be structured to minimize it.

 

Main Points:

• As more states have legalized cannabis in the US, the availability has increased and the price has fallen, resulting in increased use.

• Cannabis potency, defined as percentage of Tetrahydrocannabinol (THC), has increased dramatically; from <3% in traditional forms to 10-15% in modern strains, or up to 70% in some cannabis extracts.

• Moderate use of high-potency cannabis (THC >10%) doubles the risk of developing psychosis, while heavy use increases it 5-fold, and daily use increases it up to 9-fold

• Cannabis dependence among young adults, as well as unintentional overdoses and driving while intoxicated have all significantly increased.

• 10 out of 13 studies that monitored cannabis use over time found that those who used cannabis had a significantly increased risk of psychosis.

• Patients diagnosed with psychosis who continue to use cannabis have more frequent episodes and longer hospitalizations, than those who stop using it.

• Alternative explanations for this relationship have been investigated, but study data does not support any of these.

• The trajectory of cannabis availability and popularity is remarkably similar to that of tobacco when it was initially commercialized- where the significant health risks were not realized or appreciated until years later, at significant detriment to public health.

• The authors recommend that cannabis legalization be implemented in a way that includes careful monitoring (price, potency, consumption) to mitigate potential risks.

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Conclusions: The price and availability of cannabis is expected to play an important role in its use among the general population as legalization becomes more widespread. Increased availability and decreased price will likely lead to increased consumption, which, in turn, is expected to increase in number of both new and chronic cases of psychosis in the US.

 

Why this is a good study:

• This report is supported by multiple, independent studies which share the same. conclusion- that cannabis use is linked to an increased risk for developing psychosis

• The authors acknowledge and consider alternative explanations for the link between cannabis and psychiatric disorders.

• It compares the current, burgeoning, trends in cannabis use and policy to those of tobacco- providing a well-studied historical reference that allows an informed prediction of the future impact of cannabis.

• The authors make informed recommendations on policies that may help reduce risks.

 

Why this isn’t a perfect study:

• This study relies on data reported from other studies, and is therefore restricted by the limits of each of those studies.

 

What this study adds:

• This study consolidates the conclusions from a number of studies regarding cannabis use and the development of psychosis.

• This study provides informed recommendations about how the US can implement cannabis-monitoring policies alongside increased legalization.

 

What it doesn’t:

• This study is not a comprehensive overview of all studies related to cannabis and developing psychosis, and does not tell us whether all cannabis products present the same risks, or which may be most important to monitor.

 

Funder:  No agency funding was reported

 

Author conflicts:  None

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