The study, "Correlates of Intentions to Use Cannabis among US High School Seniors in the Case of Cannabis Legalization," used data from Monitoring the Future (MTF). The researchers found that 10 percent of non-lifetime marijuana users surveyed by MTF reported that they would try marijuana if legal.
"Our study focused on intention to use and it was the first to find that groups generally not "at risk" become more "at risk" when legalized," said Joseph J. Palamar, PhD, MPH, Assistant Professor at the Department of Population Health, NYU Langone Medical Center.
The researchers examined the most current attitudes, focusing on cohorts from 2007-2011. The data were collected prior to the legalization of recreational marijuana use in Colorado and Washington, but after legalization of medical marijuana was pending or enacted in up to 16 states.
Data were analyzed separately for the 6,116 seniors who reported no lifetime use of marijuana and the 3,829 seniors who reported lifetime use (weighted samples). The researchers looked at whether demographic characteristics, substance use and perceived friend disapproval towards marijuana use were associated with 1) intention to try marijuana among non-lifetime users, and 2) intention to use marijuana as often or more often among lifetime users, if marijuana was legal to use.
"Assuming that onset use would occur before or during the senior year, the study's results suggest that this would constitute a 5.6 percent absolute increase in lifetime prevalence in this age group, rising from 45.6 percent to 51.2 percent," Dr. Palamar said.
Not surprisingly, odds for intention to use outcomes increased among groups already at high risk for use (e.g., males, whites, cigarette smokers) and odds were reduced when friends disapproved of use. However, large proportions of subgroups of students normally at low risk for use (e.g., non-cigarette-smokers, religious students, those with friends who disapprove of use) reported intention to try marijuana if legal. Recent use was also a risk factor for reporting intention to use as often or more often among lifetime users.
"What I personally find interesting is the reasonably high percentage of students who are very religious, non-cigarette smokers, non-drinkers, and those who have friends who disapprove of marijuana use—who said they intended to try marijuana if it was legal," Dr. Palamar said. "This suggests that many people may be solely avoiding use because it is illegal, not because it is "bad" for you, or "wrong" to use."
The researchers caution that as marijuana use increases, regardless of legal status, it will become increasingly important to prevent adverse consequences that may be associated with use. Public health practitioners must continue to educate marijuana users and those at risk for initiation and/or continued use about the potential harms associated with use.