Is cannabis use disorder a risk factor for Covid-19?

New research indicates that problematic cannabis use may be linked to poorer Covid-19 outcomes.

Findings from Washington University in the US, suggest that cannabis use disorder (CUD) should be considered among the risk factors for poorer outcomes in patients with Covid-19.

Diabetes, obesity and a history of smoking cigarettes are all considered risk factors for poorer outcomes in those who contract the virus. 

Now researchers believe doctors should also take care to talk to patients who have a problematic relationship with cannabis about the potential dangers.

Findings from the study  indicated that the genetic predisposition to CUD is overrepresented in people with poor Covid-19 outcomes, although more work is needed to determine if there is direct causation.

The data suggests that heavy cannabis users may have a more adverse reaction to Covid-19 and that, much like quitting tobacco smoking or reducing BMI, reducing and/or stopping heavy cannabis use may protect against severe reactions.

Ryan Bogdan, associate professor in the Department of Psychological and Brain Sciences in Arts and Sciences at the university, said: “As sociocultural attitudes and laws surrounding cannabis use become increasingly permissive, and Covid-19 continues to spread, we need to better understand how cannabis use as well as heavy and problematic forms of use are associated with Covid outcomes.”

The team combined existing datasets to test whether being at higher genetic risk for cannabis use disorder was correlated to the risk of Covid hospitalisation.

One set of data involved 357,806 people, including 14,080 with CUD; the other involved 1,206,629 people, including 9,373 who were hospitalised with Covid.

They also looked at seven million genetic variants to assess the association between CUD and severe COVID.

In comparing people with the variants to their Covid outcomes, the researchers found genetic liability for CUD accounted for up to 40 percent of genetically influenced risk factors, such as body mass index (BMI) and diabetes, for a severe Covid-19 presentation.

Read more: Study shows cannabis use not associated with a loss in motivation

The genetic association between CUD and Covid-19 severity was present even when accounting for genetic liability to BMI as well as other risk factors for a severe reaction, including metabolic traits; respiration traits; socioeconomic status; alcohol and tobacco use; and indices of impulsivity.

According to the study’s authors the results suggest that either a predisposition to CUD and severe Covid-19 is due to a biological mechanism – such as inflammatory conditions causing individuals to develop worse symptoms of Covid-19 and/or dependence on cannabis –  or that they are associated because of a causal process.

Lead author, Alexander S Hatoum, a postdoctoral researcher in the Washington University School of Medicine, said: “We found that a person’s genetic risk for cannabis use disorder is correlated with their risk for COVID-19, without having to ask directly about illegal substance use.”

Hatoum added: “That the genetic relationship between CUD and Covid-19 is independent of these factors raises the intriguing possibility that heavy and problematic cannabis use may contribute to severe Covid-19 presentations. As such, it is possible that combating heavy and problematic cannabis use may help mitigate the impact of COVID-19.

“This information needs to be incorporated into any strategy to defeat this disease.”