More US adults using marijuana as concerns about risk decline

Marijuana use is losing some of its taboo among US adults, according to a new analysis of government survey data. In a report published in the journal Lancet Psychiatry Thursday, federal researchers conclude that pot use began increasing in about 2007, coinciding with a drop in the number of Americans who see the drug as harmful.

Researchers studied data from nearly 600,000 adults aged 18 or older who took part in the annual US National Survey on Drug Use and Health (NSDUH) from 2002 to 2014. In 2002, 10.4 percent of respondents had used marijuana in the year prior to taking the survey. By 2014, that number rose to 13.3 percent — an increase of 10 million people.

In the same period, the number of first-time marijuana users and the prevalence of daily or near-daily use also increased.

But the proportion of American adults who believe smoking marijuana once or twice a week is harmful decreased, from 50.4 percent to 33.3 percent, reported the researchers from the National Institute on Drug Abuse and the US Department of Health and Human Services.

“(A)dults have perceived less risk of harm from marijuana use since 2006–07,” wrote the researchers. “And these declining risk perceptions were associated with increases in marijuana use and frequency of use.”

Columbia University researchers reported similar results in June among teens, and the authors of the new paper noted that while shifts in perceived risk of marijuana use have long been known to predict trends in pot use among adolescents, no previous research had examined the relationship among adults.

In a commentary accompanying the Lancet Psychiatry report, King’s College of London addiction researchers Michael Lynskey and Wayne Hall were cautious about tying the reduced perceptions of harm to the passage of laws in many states legalizing medical marijuana.

“It is probably too soon to draw conclusions about the effects of these legal changes on rates of cannabis use and cannabis-related harms,” he wrote, “but it is likely that these policy changes will increase the prevalence and frequency of cannabis use and, potentially, cannabis use disorders in the longer term.”

Despite the increase in marijuana use noted in the study, the researchers surprisingly found a decrease in marijuana abuse or dependence during the study period. But they noted that the number may be skewed by the fact that the study did not include people who were homeless and not living in shelters or incarcerated. These groups could increase numbers for disordered use of the drug.

In any case, they wrote, “Future research on trends in marijuana abuse and dependence and their relationships with perceived risk could help elucidate reasons for the discrepancy between marijuana use patterns and use disorders.”