While diabetes, obesity and a history of smoking cigarettes are considered as risk factors for poorer Covid-19 outcomes, a new study claims that people with cannabis use disorder (CUD) may also be at increased risk.
Having genetic variants does not mean a person has CUD or that the person has used cannabis.
But, comparing people with the variants to their Covid outcomes, the researchers found genetic liability for CUD accounted for up to 40 per cent of genetically influenced risk factors, such as body mass index (BMI) and diabetes, for a severe Covid-19 presentation.
This association suggested that heavy and problematic cannabis use may represent a modifiable pathway to minimise severe Covid-19 presentations, the researchers explained, in the journal Biological Psychiatry: Global Open Access.
The study point to two possible outcomes: That a predisposition to CUD and severe Covid-19 are due to a common biological mechanism, like 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, said Alexander S. Hatoum, a postdoctoral researcher at the varsity.
"If we know the genes that predispose individuals to cannabis use disorder, and if cannabis use disorder is a risk factor for Covid-19 hospitalisation, you will see the genes influencing cannabis use disorder as predictors of severe Covid-19 cases," he 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," he added.
For the study, 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 7 million genetic variants to assess the association between CUD and severe Covid.