Signs of emphysema may develop early in pot smokers

NEW YORK (Reuters Health) - Pot smokers may experience pathological changes in their lungs decades earlier than such changes usually occur in cigarette smokers, a small study of 10 patients shows.

The patients' average age was 41 years and they reported smoking marijuana regularly for at least 1 year. The main feature in all patients was air pockets in the lungs known as bullae, which are typically seen in people with emphysema that develops after many years of cigarette smoking.

About 15 percent of cigarette smokers will develop emphysema by age 65, but less is known about the effects of marijuana on the lungs, Dr. Su W. Hii of Monash University in Victoria, Australia and colleagues note. Because pot smokers typically inhale hot smoke forcefully and hold it in their lungs for as long as possible, the researchers add, it's possible that they may be doing more damage to their lung tissue.

To investigate, Hii and colleagues evaluated 10 marijuana smokers who sought treatment for respiratory symptoms. Four had difficulty breathing, four had collapsed lungs, and two had lung infections. The findings are published in the journal Respirology.

CT scans identified bullae in all of the patients, with nine having severe bullous disease. Seven subjects were in-patients with acute respiratory disorders and one patient had a long history of asthma.

However, five of the patients had normal lung function and the other four had only mildly reduced lung function. Chest X-rays were normal in four patients.

It is estimated that up to 2 percent of the U.S. population are regular marijuana smokers, the researchers note. They therefore call for further study to determine how common such lung disease is among marijuana smokers and to compare pot-related lung damage to the harmful effects of tobacco.

SOURCE: Respirology, January 2008.