Is Cannabis Use Associated With Pulmonary Disease And COVID-19?

A new study using data from 500 thousand participants is shedding light on the effects of smoking cannabis on the lungs of users.

In a new study released this week, researchers used data from UK Biobank (UKB) to evaluate the effect of cannabis on coronavirus disease (COVID-19) infection and to determine whether cannabis lung damage might facilitate COVID-19 infection in formerly regular users.

The UKB study -a prospective observational study comprising about 500,000 men and women from across England, Wales and Scotland, between 2006 and 2010. Included in the study were all UKB subjects who had cannabis-use data, COVID-19 test data, and chronic obstructive pulmonary disease (COPD) data.

From March 16 to April 26, 2020, the electronic linkage between UKB records and National Health Service COVID-19 laboratory test results in England was made available.

The study results said that cannabis can produce lung diseases with increasing years of use, and cause weakening in the immune system, leading to pneumonia. In addition, researchers said that heavy use of cannabis can result in airway obstruction and worse COVID-19 outcomes.

"As soon as a tobacco smoker quits, his chances are diminished of getting cancer and other diseases. Our findings imply that cannabis may be similar. Fifteen years after quitting tobacco, the risk of coronary heart disease is close to that of a nonsmoker. Unlike the heart, the lung does not forget the insult from inhaled tobacco or cannabis, even many years later, but after quitting the lung damage may not further increase," the researchers said.

In 2012, a study stated that occasional and low cumulative marijuana use was not associated with adverse effects on pulmonary function. At the time, researchers concluded that cannabis use did not cause loss of air flow rate and lung volume. 

However, the latest study concluded that cannabis use might reduce lung inflammation and inhibit viral replication in Covid-19 infections, leading to a better outcome.
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