Research published in Lancet Psychiatry also finds number who admit to smoking on ‘daily or near daily basis’ more than doubled to 8.4 million, About 10 million more Americans smoke marijuana now than 12 years ago, a new study in the British medical journal Lancet Psychiatry has found.
The study comes as at least five states ready to vote on whether to legalize marijuana for recreational purposes, including California, which is considered a linchpin in the campaign for federal legalization.
“We certainly expected, based on other research, to find an increase” in marijuana use, said said Dr Wilson M Compton, an author of the study and researcher at the National Institute on Drug Abuse. “It’s well known in the US that the laws related to marijuana have been changing; we’ve seen a number of states passing laws to allow marijuana for medical purposes.”
The study used data from 596,500 adults surveyed between 2002 and 2014 for the US National Survey on Drug Use and Health to reach its conclusions about how many Americans use smoke marijuana.
One of the study’s key findings is that between 2002 and 2014, the percentage of Americans who said they smoke marijuana at least once in the previous year grew from 10.4% to 13.3%.
The 2.9% increase equates to an additional 10 million Americans who said they used the drug at least once in the past year, bringing the population who admitted use from 21.9 million in 2002 to 31.9 million in 2014.
One of the most surprising findings, Compton said, “is how many people there are using marijuana in a daily or near daily basis”.
That number more than doubled, from 3.9 million to 8.4 million, or 1.9% of the US population to 3.5%, over the same period. The proportion of adults who first tried to smoke marijuana also increased, from 0.7% to 1.1%.
However, researchers did not find a rise in the proportion of Americans who abused marijuana, called a “use disorder” in psychiatric terms. That number stayed flat at 1.5% of the general population. The figure contradicts a survey the federal government released last year, which found the rate of people who abused marijuana roughly doubled from 1.5% to 2.9% between 2001 and 2012.
“Our findings showed a sharp increase,” said Deborah Hasin, a professor of epidemiology in psychiatry at Columbia University. Hasin was lead author of the National Epidemiological Survey on Alcohol and Related Conditions, which found the sharp increase in use disorders. “That’s consistent with a sharp increase of people going to emergency rooms with marijuana use, marijuana-related driving and fatal car crashes, and in Veterans Administration medical records,” Hasin said.