Pot and Alcohol Each Have Risks

Ty Schepis is an assistant professor of psychology at Texas State University, San Marcos.

Updated December 19, 2011, 8:23 PM

As a starting point, it helps to drill down and understand what the Monitoring the Future study tells us about how teenagers’ marijuana use is changing. While more high school seniors in the U.S. reported daily marijuana use, the percentage of daily users in the 10th grade is lower than it was for any year from 1996 to 2003. The percentage of teenagers who say they have used marijuana in the last year or the last month is still below the peaks in the late 1990s and early 2000s across students. The more concerning data I see from the study indicate that the perception of “great risk” from regular use has generally fallen year-on-year for the past four (see Pages 10 and 11). Lower perceptions of risk usually coincide with or precede increases in use.

The perception of 'great risk' from regular use of marijuana has generally fallen, but it is associated with a long list of mental and physical problems.

Stating that marijuana use is replacing alcohol use appears true only for daily users, but this has been the case annually since 1994. If we look at use in the past year or the past month, however, alcohol is used by roughly double the proportion of students. Cocaine has never been used as frequently as marijuana. Tobacco may be the one substance that marijuana overtakes, but changing attitudes about tobacco use appear to be the most important driver of this trend.

As to the relative harms of alcohol and marijuana use, alcohol use does cost society more in terms of lost productivity, property damage, injury and mortality. But the proportion of alcohol users is also much higher than the proportion of marijuana users, especially among adults. This highlights the need to frame any discussion in terms of burden per user, not necessarily as a total societal cost.

Furthermore, I am always concerned about describing one drug as less “worrisome” than another. The science indicates that for adolescents, regular and/or heavy use of either alcohol or marijuana is detrimental. Regular adolescent marijuana use is associated with schizophrenia development, suicidal behavior, verbal and spatial memory deficits, executive functioning abnormalities, and a variety of health problems in adulthood. Judging whether regular and/or heavy adolescent marijuana or alcohol use is more detrimental seems imprudent, when the evidence indicates that such frequent use of either substance by adolescents is a significant problem.