The average potency of today’s marijuana (the concentration of tetrahydrocannabinol or THC) is 200% higher than the average potency of marijuana smoked in the mid-1990s. THC concentrates range in potency from 40% to 80%. Parents shouldn't dismiss today's teen marijuana use based on their own use of lower potency pot when they were young.

Decades of research on the negative effects of marijuana on the developing brain are yielding disturbing results. These findings — many of which point to long-term and permanent cognitive deficits — should concern parents and teenagers. Marijuana use is associated with:

  • lower academic achievement

  • high school and college dropout

  • serious mental health problems, and

  • chronic, lifelong struggle with drug addiction.

While many teenagers use marijuana with no apparent ill effects, the drug robs many others of their future.


Nora Volkow, MD, Director of the National Institute on Drug Abuse, presented on the effects of marijuana use on the brain, body and behavior at the 2014 CADCA National Leadership Forum.

She notes that the reason alcohol and tobacco are the most widely used drugs is their legal status. With regard to the changing legal status of marijuana through ballot initiatives, Dr. Volkow states that “people are voting without the knowledge."


Vaporizing is the intake of marijuana vapor by using a device that creates steam to inhale rather than the traditional inhalation of smoke produced by burning leaves. Vaping devices were originally developed to create an alternative way to inhale nicotine. The marijuana industry has co-opted these devices, which deliver a high percentage of THC rapidly to the bloodstream. For more about this topic check out "Vaping" - The Transformation of Marijuana.

Trends in Adolescent Marijuana Use

Largely because of the legalization of marijuana for medical and recreational use in several states, the drug is more available, accessible — and socially accepted. Even though youth rates of substance use are generally down in the US, those same declines are not seen in rates of youth marijuana use. This can be seen in the following graph of data from the Monitoring the Future study.

Past Month Substance Use by US High School Seniors: 1976-2017, Monitoring the Future

Past Month Substance Use by US High School Seniors: 1976-2017, Monitoring the Future

Most recently, in 2018, 22.2% of American high school seniors used marijuana in the past month and 5.8% used the drug daily. There are also concerns about the use of marijuana among young adults:

Sherberne, M. (2018, September 5).  Marijuana use among US college students remains at highest level in three decades . University of Michigan.

Sherberne, M. (2018, September 5). Marijuana use among US college students remains at highest level in three decades. University of Michigan.


This brief documentary provides an inside look at weed culture at an unnamed high school in Portland, Oregon.

Students share their experiences about smoking marijuana, including use of mooks, dabs, and other marijuana-based products. The documentary shows how marijuana use can lead to problems for many young people and demonstrates a disconnect that exists between students and teachers on the subject of drugs.



ElSohly, M. A., Mehmedic, Z., Foster, S., Gon, C., Chandra, S., & Church, J. C. (2016). Changes in cannabis potency over the last 2 decades (1995-2014): analysis of current data in the United States. Biological psychiatry, 79(7), 613–619.


Just Think Twice. The facts about marijuana concentrates; National Institute on Drug Abuse. (2019). DrugFacts: marijuana.


Centers for Disease Control and Prevention. (2017). What parents need to know about marijuana use and teens. Atlanta, GA: CDC.


Smart Approaches to Marijuana (SAM). Center for marijuana resources.


Johnston, L. D., Miech, R. A., O’Malley, P. M., Bachman, J. G., Schulenberg, J. E., & Patrick, M. E. (2019). Monitoring the Future national survey results on drug use 1975-2018: Overview, key findings on adolescent drug use. Ann Arbor: Institute for Social Research, University of Michigan.

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