What Does Research Tell Us About Marijuana & Addiction?

July 18, 2017   Thomas G. Kimball, PhD

Published in The Doctor Weighs In, July 18, 2017. View the Article Here

In discussions on substance use disorder (SUD) and addiction, I often come across claims from marijuana advocates that marijuana is either:

  • Not addictive
  • “Safer” than other illicit substances
  • Less addictive than substances like cigarettes, alcohol, and other illegal drugs.

These argument, while prevalent in the media and society, are somewhat unfounded and misguided in the way they are framed and explained. I have outlined a brief but thorough clarification on the medical view and background of marijuana’s impact on society and the chronic disease of addiction.

Some history about marijuana

The plant cannabis (e.g., Cannabis sativa; Cannabis indica and Cannabis ruderalis), most often called marijuana, has grown wild in many tropical places in the world for thousands of years. Ten thousand (10,000) years ago, during the Neolithic period, the plant was used for cloth, rope, food, ritual, and medicinal reasons.1 The first crop production of Cannabis is recorded in China somewhere between 3000–2700 B.C. Other parts of the plant, particularly the female resinous portion have been used medicinally for centuries as a painkiller, sedative, anti-anxiety/depressant, and so forth.1,2

Apart from these uses, there is hard evidence of humans’ using marijuana for euphoric purposes starting as early as 2700 BC. This early use is evidenced by archeological sites in China. For example, in a gravesite in Northwest China, archeologists found well-preserved flower tops buried with a shaman man. When analyzed these flower tops contained THC (or tetrahydrocannabinol) which is the main psychoactive portion of the marijuana plant.1 Although this may be the earliest evidence of THC, it is a safe bet that humans have used marijuana for euphoric purposes for thousands and thousands of years.

Awarded works such as Martin Lee’s book Smoke Signals (2012) on the social history of marijuana use in all its forms, teaches us that once marijuana is introduced to a culture it sticks. He points out:

“As it (marijuana) traveled from region to region, the pungent plant never failed to ingratiate itself among the locals. Something about the herb resonated with humankind. Once it arrived in a new place, cannabis always stayed there—while also moving on, perpetually leaping from one culture to another.”

How prevalent is marijuana use?

Within the United States, marijuana has indeed ingratiated itself within our culture. The National Institute on Drug Abuse (NIDA) reports that marijuana is the “most commonly used illicit drug”. According to the 2015 National Survey on Drug Use and Health, it is estimated that 22.2 million people in America used marijuana this past month. Interestingly, the use of marijuana is more common among men than woman; a gender gap which has widened in the past 7 years.3

What about our adolescents?

Unfortunately, marijuana is significantly used by adolescents and young adults. There seems to be almost a casual, no big deal attitude about the use of marijuana for euphoric reasons among many of today’s youth. This casual attitude toward marijuana use is evidence by the numbers. In a 2016 study, researchers reported, among U.S. 10th graders, almost 24% had used marijuana during the past year with 14% reporting they had used it in the last month. As teens get older, the use tends to increase. For example, for 12th graders, the past year use of marijuana numbers climb to almost 36% and monthly use rises to almost 23%. Most alarming is that 6% of 12th graders use marijuana daily.4,5

Putting the argument of legalizing marijuana for medicinal and/or recreational use aside, we, as a culture and society, must recognize the negative impact of marijuana use on individuals, families, and communities. Given the rate of adolescent use, we must pay particular attention to the short- and long-term impact of marijuana on the teenage brain.

What does the research tell us about marijuana use and the teenage brain?

A growing body of research, both animal and human, provides strong evidence of the impact of marijuana use on the adolescent brain with lasting impairment. Specifically, cognitive impairment includes damage to the learning and memory systems of the brain. Marijuana use changes the structure and function of the brain impacting executive functioning of memory, learning, and impulse control. Altering the reward system’s pathways through marijuana use increases the likelihood of engaging in other high-risk drug use and other high risk/reward behaviors (NIDA).4 It makes sense that the earlier a person begins using marijuana, the amount of marijuana used and the length of time (months/years) of the use all factor in the severity of the cognitive damage.

Further evidence of the impact of marijuana use and cognitive impairment—a longitudinal study of adolescents from New Zealand followed over many years—showed marijuana use started in adolescence was correlated with a loss of 6 to 8 IQ points. The most disturbing finding was that even when marijuana use was later stopped in adulthood, the lost IQ points were never recovered.6,7

Is marijuana addictive?

The impact of marijuana use on an adolescent’s brain is compelling and disturbing. Even more alarming is the misconception that marijuana is not addictive. It has been shown that its use can lead to the manifestation of the chronic brain disease of addiction. From the National Institute on Drug Abuse,

“Nine percent of people who use marijuana develop an addiction. This rate nearly doubles to 17 percent when marijuana use begins during the teen years. Among youth receiving substance use disorder treatment, marijuana accounts for the largest the largest percentage of admissions—about 55 percent among those 12 to 17 years old.”

Marijuana historical research, its prevalence in the U.S. particularly among adolescents, and the damage it causes should compel us to stop and take notice. We must utilize smart tactics of prevention, intervention, and support to assist those we love, especially including our young people, in finding wellness.

How can we help?

There is no sure way to prevent someone from abusing marijuana. Prevention advocates support talking openly with your children about all kinds of topics including drug and alcohol use and remaining close to them. A great start is visiting the National Institute of Drug Abuse’s website and reading this: Marijuana: Facts Parents Need to Know.

It is important to remember that not all marijuana use means your loved one has manifested with the disease of addiction. Many people experiment with marijuana but do not develop an addiction. Take time to gather the facts when you find your loved one has used or is using marijuana. Do your best not to respond using a fear-based approach but rather with love, honesty, and support if there is a problem. Reach out to trained and licensed professional who can help screen and assess the kind of assistance you and your loved one need.

When helping to prevent, treat, and support ourselves and our loved ones toward wellness and away from destructive and frequent marijuana use, the more people you have on your team the better. Team members can include supportive family, counselors, therapists, friends, religious leaders, recovery support specialists, positive peers and communities, and a host of others. The most important thing to realize is we do not have to be alone in figuring out what the next right thing is to do.

1. Lee, Martin A. (2012). Smoke Signals: A Social History of Marijuana—Medical, Recreational, and Scientific, Scribner, NY.
2. Jones, N. (2005) Spliffs: A Celebration of Cannibis Culture, Collins & Brown, London.
3. Carliner, H., & Mauro, P. M., Brown, Q. L., et al. (2016). The widening gender gap in marijuana use prevalence in the U.S. during a period of economic change, 2002-2014. Drug Alcohol Depend. 170:51-58.
4. National Institute On Drug Abuse (NIDA). https://www.drugabuse.gov/publications/research-reports/marijuana/what-scope-marijuana-use-in-united-states
5. Johnston L, O’Malley P, Miech R, Bachman J, Schulenberg J. (2016). Monitoring the Future National Survey Results on Drug Use: 1975-2016: Overview: Key Findings on Adolescent Drug Use.Ann Arbor, MI: Institute for Social Research, The University of Michigan.
6. National Institute on Drug Abuse (NIDA). https://www.drugabuse.gov/publications/marijuana/what-are-marijuanas-long-term-effects-brain
7. Rubino, T., Zamberletti, E., & Parolaro, D. (2012). Adolescent exposure to cannabis as a risk factor for psychiatric disorders. J Psychopharmacol Oxf Engl. 26(1):177-188.

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