Cannabis plus cigarettes linked to COPD14th April 2009
Smokers may increase their risk of developing with chronic obstructive pulmonary disease (COPD) if they also smoke marijuana, according to a recent study presented at the American Thoracic Society and published in a key journal.
While smokers over 40 were two-and-a-half times more likely than nonsmokers to develop COPD, those who smoked cigarettes and marijuana together boosted the odds of developing COPD to three-and-a-half times of someone who did neither.
Study lead author Wan Tan, of St. Paul's Hospital in Vancouver, British Columbia, said that the odds of cigarette smokers having any respiratory symptoms was 2.36 times that of nonsmokers.
Meanwhile, the odds of someone who smoked both cigarettes and marijuana having respiratory symptoms was 18 times that of someone who smoked neither.
Studies on the respiratory consequences of pot smoking have yielded conflicting results, with one recent study linking daily marijuana use to a higher lung cancer risk. Other studies have failed to show such a connection, however.
Tan said her findings, published in the Canadian Medical Association Journal, had major public health implications.
In both younger and older adults in the study, 30% smoked both cigarettes and marijuana. Among younger cigarette smokers, 76% also smoked marijuana, while 58% of older cigarette smokers also smoked marijuana.
The majority of cigarette smokers in the 648 adults over 18 studied were also marijuana smokers. Younger participants answered questions on respiratory symptoms, while those over 40 had lung function tests.
Both cigarette and marijuana smoking is prevalent in the Vancouver area, with 49% of participants ages 18 to 39 and 46% of those 40 and older reporting having smoked marijuana at least once.
In the 18-39 age group, 17% said they currently smoked marijuana, compared with 13% in the 40+ age group.
Pot smoking by itself, however, has not been linked to a higher risk of COPD.
Tan's team said the findings suggest that marijuana and cigarette smoking may act "synergistically" to promote COPD, speculating that marijuana smoking sensitizes the airways, making them more vulnerable to the adverse effects of tobacco smoking.
They found that men and women who smoked both tobacco and marijuana were more than twice as likely as non-smokers to have frequent respiratory symptoms, if they'd had more than 50 joints over a lifetime, and were nearly three times more likely to get COPD than non-smokers.
But Tan said a much larger study and a marijuana-smoking cessation study would be needed to demonstrate the impact of marijuana on lung function and risk of COPD.
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Title: Cannabis plus cigarettes linked to COPD
Author: Luisetta Mudie
Article Id: 10965
Date Added: 14th Apr 2009