WEDNESDAY, Dec. 6, 2017 -- A strong link exists between smoking and daily marijuana use, with U.S. smokers 10 times more likely to use pot every day, a new study says.
And teen smokers are 50 times more likely than their nonsmoking peers to use pot daily, said researchers from Columbia University and City University of New York.
"While we found that daily cannabis use and cigarette smoking were strongly linked among all subgroups, the most striking finding in daily cannabis use was among youths aged 12 to 17 years," said principal investigator Renee Goodwin. She's an epidemiologist at Columbia's Mailman School of Public Health.
"Nearly one-third of youth who smoke cigarettes reported using cannabis every day. In contrast, less than 1 percent of youth who did not use cigarettes reported daily cannabis use," Goodwin said in a university news release.
"We are not aware of any previous reports illustrating that daily cannabis use in youths occurs nearly exclusively among those who smoke cigarettes," Goodwin said.
She and her colleagues analyzed 2002-2014 data from the National Survey on Drug Use and Health. Questions covered lifetime, past and current use of cigarettes and marijuana.
The study showed that daily pot use rose from 5 percent in 2002 to 9 percent in 2014 among daily cigarette smokers and from 3 percent to 8 percent among nondaily cigarette smokers.
Also, daily marijuana use rose fastest among former smokers -- from less than 1 percent in 2002 to almost 3 percent in 2014.
The largest increase in marijuana use occurred among adults 26 and older.
But young cigarette smokers ages 12 to 17 were 50 times more likely to be daily marijuana users than teens who avoided cigarettes, the researchers found.
In that age group, 28 percent of daily cigarette smokers and 13 percent of nondaily cigarette smokers used marijuana daily in 2014. That suggests 4 out of 10 young smokers used marijuana every day.
Smoking has declined significantly in the United States in recent decades, but the drop has slowed in recent years.
"It is conceivable that this stunted decline in cigarette use is owing, in part, to the substantial increase in daily cannabis use among smokers," Goodwin said.
"Understanding the degree to which daily cannabis use may be common among cigarette smokers is critical because previous findings suggest that any past month cannabis use is associated with smoking persistence and relapse," Goodwin concluded.
The study was published online recently in the American Journal of Public Health.
The U.S. National Institute on Drug Abuse has more about marijuana.
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