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Heavy Habitual M rijuana Smoking Doe's Not Cause
<br />an Accelerated Decline in FEV, With Age
<br />DONALD Is. TASHKIN, MICHAEL S. SIMMONS, DUANE L SHERRILL, and ANNE H. COULSON
<br />Depenments of Medicine and Epidemiology, UCIA Schools ol'Medkine and Public Health, Los Angeles;
<br />and Division of Respiratory Sciences, University of Arizona College of Medicine, Tucson, Arizona
<br />To assess the possible role of daily smoking of marijuana in the development of chronic obstructive .
<br />pulmonary disease (COPD), we evaluated the effector habitual use of marijuana with or without tobacco
<br />on the age-related change in lung function (measured as FEVs) in comparison with the effect of non-
<br />smoking and regular tobacco smoking. A convenience sample of 394 healthyyoung Caucasian adults
<br />(68% men; age: 33 t 6 yr; mean 3 SD) Including, at study entry, 131 heavy, habitual smokers of mariju-
<br />ana alone, 112 smokers of marijuana plus tobacco, 65 regular smokers of tobacco alone, and 86 non-
<br />smokers of either substance were recruited from the greater Los Angeles community. FEV1 was mea-
<br />sured in all 394 participants at study entry and In 25S subjects (6S %) on up to six additional occasions
<br />at Intervals of l, 1 yr (1.7 t 1.1 yr) over a period of 8 yr. Random -effects models were used to estimate
<br />mean rates 2f decline in FEVs and to compare these rates between smoking groups. Although men
<br />showed a significant effect of tobacco on FEV1 decline (p G 0.05), in neither men nor women was
<br />marijuana smoking associated with greater declines In FEVs than was nonsmoking, not was an addi-
<br />tive effect of marijuana and tobacco noted, or a significant relationship found between the number
<br />of marijuana cigarettes smoked per day and the rate of decline in FEVI. We conclude that regular
<br />tobacco, but not marijuana, smoking is associated with greater annual rates of decline in lung function
<br />than Is nonsmoking. These findings do not support an association between regular marijuana smoking
<br />and chronic COPD but do not exclude the possibility of other adverse respiratory effects.Tashkin DP,
<br />Simmons MS, Sherrill DL, Coulson AH. Heavy habitual marijuana smoking doer not cause an
<br />accelerated decline In FEVI with age. "r WPM Carr esu Mrs) 1se7:uusu..lu.
<br />Marijuana remains the most commonly smoked illicit substance
<br />In American society (I, 2). After more than a decade of declin-
<br />ing prevalence of marijuana use in the United States, an upswing
<br />in its usehas recently been demonstrated, especially among young
<br />individuals (1, 2). Because the constituents or marijuana smoke
<br />are similar In many respects to those or tobacco (3, 4), it is possi.
<br />bit that habitual smoking of marijuana may lead to some of the
<br />same respiratory erfats that derive from regular tobacco use.
<br />This possibility is supported by several animal and cellular studies,
<br />which have shown that chronic exposure to marijuana smoke
<br />can Injure respiratory tissue (5-9). Although earlier studies in
<br />humans yielded conflicting data about the association between
<br />heavy marijuana smoking and clinical evidence of respiratory
<br />illness (10-14), more recent clinical studies have demonstrated a
<br />relationship between habitual marijuana use and symptoms of
<br />chronic bronchitis (15, 16). Moreover, histopathologic studies have
<br />revealed epithelial alterations in biopsies from proximal bronchi
<br />(Recatved N odginol form Ap61 3, 1996 and in revised form rune 25, 1996)
<br />Suppomd by Grant No. ROl D.A03019 from the National Insdtums of
<br />HsafWNauonal Institute m Drug Abuse.
<br />Correspondence and request$ for reprp,u should be addressed to Donald P.
<br />Taihkin. M.D. Department of Medicine, VCtA School'of MedKlne, los An-
<br />gelese CA 90095-1690.
<br />AM I Vspir Crit Care Med vol 135. pp 141-148. 1997
<br />of marijuana smokers (goblet -cell metaplasia, reserve -cell hyper-
<br />plasia, squamous metaplasia) (17, 18) that are consistent with
<br />symptoms of mucus hypersecretion.
<br />In contrast to the concordance of findings in recent studies
<br />with respect to the impact or regular marijuana smoking on
<br />chronic respiratory symptoms, cross-sectional studies or mariju•
<br />ana users in Los Angeles (I5) and of smokers of nontobacco (pre.
<br />sumably and hereafter referred to as marijuana) in Tucson (16)
<br />have revealed conflicting effects on lung function. The Los An-
<br />geles study (15) failed to demonstrate any relationship between
<br />marijuana use and impairment in tests of lulls function, includ-
<br />ing sensitive indices of small airways dysfunction, whereas the
<br />Tucson study (16) demonstrated obstructive ventilatory defects
<br />additive to those attributable to regular tobacco use Recent anal-
<br />ysis of longitudinal data from the Tbcson study (19) estimated
<br />significant decrements in FEV, in continuing male (but not fe.
<br />male) marijuana smokers �a I yr after marijuana smoking was
<br />first reported. Moreover, these decrements were twice as large
<br />as the estimated decrements in continuing tobaccosmokers, and
<br />the effects of both habits were additive. The latter data suggest
<br />that marijuana smoking might be a significant risk factor for
<br />Progressive airflow obstruction.
<br />To further evaluate the possibility that continuing marijuana
<br />smoking might lead to progressive declines in lung function not
<br />consistently apparent in cross-sectional studies, we invited non-
<br />smokers and smokers of marijuana and/or tobacco who were
<br />participants In a cohort study of the pulmonary effects of habitual
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