Am. J. Respir. Crit. Care Med., Vol 155, No. 1, 01 1997, 141-148.
Heavy habitual marijuana smoking does not cause an accelerated decline in FEV1 with age
DP Tashkin, MS Simmons, DL Sherrill and AH Coulson
Department of Medicine, UCLA Schools of Medicine and Public Health, Los Angeles, CA 90095-1690, USA.
To assess the possible role of daily smoking of marijuana in the
development of chronic obstructive pulmonary disease (COPD), we evaluated
the effect of habitual use of marijuana with or without tobacco on the
age-related change in lung function (measured as FEV1) in comparison with
the effect of nonsmoking and regular tobacco smoking. A convenience sample
of 394 healthy young Caucasian adults (68% men; age: 33 +/- 6 yr; mean +/-
SD) including, at study entry, 131 heavy, habitual smokers of marijuana
alone, 112 smokers of marijuana plus tobacco, 65 regular smokers of tobacco
alone, and 86 nonsmokers of either substance were recruited from the
greater Los Angeles community. FEV1 was measured in all 394 participants at
study entry and in 255 subjects (65 %) on up to six additional occasions at
intervals of > or = 1 yr (1.7 +/- 1.1 yr) over a period of 8 yr.
Random-effects models were used to estimate mean rates of decline in FEV1
and to compare these rates between smoking groups. Although men showed a
significant effect of tobacco on FEV1 decline (p < 0.05), in neither men
nor women was marijuana smoking associated with greater declines in FEV1
than was nonsmoking, nor was an additive effect of marijuana and tobacco
noted, or a significant relationship found between the number of marijuana
cigarettes smoked per day and the rate of decline in FEV1. We conclude that
regular tobacco, but not marijuana, smoking is associated with greater
annual rates of decline in lung function than is nonsmoking. These findings
do not support an association between regular marijuana smoking and chronic
COPD but do not exclude the possibility of other adverse respiratory
effects.
