Humans and other animals have an “endocannabinoid system” that extends throughout the body. This system controls many functions like pain management, inflammation, sleep, emotional processing, and memory.
The endocannabinoid system releases chemical signals called “endocannabinoids” that are used by the brain and nervous system to regulate many of our body’s functions, like appetite, pain, movement, mood, and immune function.
Endocannabinoids are similar to molecules called “cannabinoids” that are found in the cannabis plant. Cannabinoids work a lot like endocannabinoids, signaling the same brain and nervous system receptors when cannabis is consumed. Because adolescent and young adult brains are still developing (through age 25), cannabis use can have greater impacts on the brains of teens and youth compared to the brains of older adults. As a parent or guardian, it’s important to be aware of the effects cannabis consumption during adolescence can have on your child’s brain and mental health and to learn how to effectively talk about these risks with your kids.
Adolescence is a critical period of brain development, especially for parts of the brain responsible for cognition (learning, attention, e.g.), decision making, and emotional regulation1. These parts of the brain have many endocannabinoid receptors, so cannabinoids like THC, the primary psychoactive component of cannabis, can play an influential role in how they function. Cannabis use during this pivotal period of development increases the chances of short-term and long-term negative impacts on these parts of the brain.
Cognitive impairments & IQ
Cognitive impairments such as slower processing speed, reduced attention, and poor verbal memory are very common for people under the influence of cannabis. Although these impairments are often temporary for adult users, in adolescents, they are more likely to persist after cannabis use has stopped2. Some research even suggests these impairments can cause long-term damage into adulthood2; however, the likelihood and severity of long-term impairments vary depending on the amount of THC used and how it is consumed6.
Starting cannabis use at an early age, using cannabis frequently, and consuming highly concentrated products increases the chance of more severe cognitive impairments2,3. These impairments can result in consequences like worse grades, increased likelihood of dropping out of school, and reduced job performance2.
Frequent adolescent cannabis use also increases the chance of lowering IQ. However, more research is needed to understand how much cannabis decreases IQ and whether this decrease lasts into adulthood8.
Reward and stress system
Adolescent cannabis use also affects the development of the body’s reward and stress system. Cannabis consumption temporarily contributes to an increase in pleasure and decrease in perceived stress while the user is “high”2. However, chronic cannabis users can develop tolerance to THC as they regularly use it, which can impair the pleasure and stress systems2. This tolerance can result in symptoms of depression and decreased motivation. This effect is more pronounced for teens who are using cannabis because fundamental parts of their brains are still rapidly developing.
“Substance use disorder” is the diagnosis used to describe addiction. People with substance use disorder (SUD) experience problems related to their use and keep using despite these problems.
Symptoms of SUD include5:
- Taking the substance in larger amounts or for longer than you mean to.
- Being unsuccessful at quitting or reducing use.
- Spending a lot of time getting, using, or recovering from using the substance.
- Craving the substance when you’re not using.
- Building a tolerance to the substance (requiring more to achieve the same effect).
- Experiencing withdrawal when not using.
- Giving up important social, occupational, or recreational activities because of substance use.
- Neglecting other activities such as school, work, or hobbies.
- Continuing to use even when it’s causing problems with friends, family, and loved ones.
- Using the substance in unsafe situations.
Substance use disorders happen on a spectrum – some people experience all these problems while others only experience a few. The number of problems and their intensity can determine how severe a person’s substance use disorder is.
Regular use of a drug like cannabis can lead to substance use disorder. About 30% of people who use cannabis have some degree of “cannabis use disorder” (CUD)6. People can develop CUD at any age, but youth who begin using cannabis before age 18 are 4-7 times more likely to develop cannabis use disorder than adults6. This risk is even higher when adolescents use highly potent products like concentrates or use cannabis frequently3. Teens with CUD are also more at risk for developing other substance use disorders by young adulthood, such as opioid use disorder or alcohol use disorder2.
Cannabis and psychosis & psychotic disorders
“Psychosis” refers to a set of symptoms that affect the mind, distorting a person’s reality and making it difficult to distinguish what is real and what is not. The two most common symptoms are hallucinations (seeing, hearing, or feeling things that others do not see or hear) and delusions (false beliefs)7.
“Psychotic disorders” such as schizophrenia are debilitating, lifelong illnesses that are often identified in adolescence and young adulthood. People with these conditions often experience paranoia, agitation, and other disordered behaviors in addition to psychosis.
Cannabis use can cause temporary psychosis, especially when it’s consumed daily or in high concentrations of THC. These symptoms can be frightening and last from a few hours to a couple of days. Although rare, daily cannabis use, particularly of high-potency products, increases the risk of developing chronic, lifelong psychotic disorders such as schizophrenia3.
For people who have a diagnosed psychotic disorder, daily use of cannabis often worsens psychotic symptoms3, particularly among those who consume high-THC products daily3. Additionally, among people diagnosed with a psychotic disorder, cannabis use during adolescence was associated with an earlier onset of psychotic symptoms2,3. Adolescents who consumed high-THC products daily experienced psychotic symptoms 2-6 years earlier on average compared to youth who didn’t2. Because of these risks, it’s advised that people at risk of or already diagnosed with psychotic disorders refrain from cannabis use.
Cannabis and anxiety & depression
Unlike psychosis and psychotic disorders, the connection between cannabis use and anxiety and depression are not quite as clear. Depressive symptoms, like depressed mood (sadness, hopelessness), decreased motivation, and reduced ability to experience pleasure (“anhedonia”), are the most common mental health symptoms associated with adolescent cannabis use.
Adolescents who use cannabis are more likely to experience depression, suicidal ideation, and suicide attempts by young adulthood2. These symptoms are often more intense when cannabis is used frequently2. Additionally, teens who use high-THC cannabis are more likely to have anxiety than those who do not2,3.
As shown above, many teens in Washington State who used cannabis monthly in 2021 struggled with symptoms of anxiety and depression. However, does cannabis use cause these symptoms or are teens struggling with depression or anxiety more likely to use cannabis to cope? The research on this is still unclear. If your teen is struggling with their mental health, talk to their doctor about treatment options that have been researched and tested to be effective.
- Arain M et al. Maturation of the adolescent brain. Neuropsychiatr Dis Treat 2013;9:449-461.
- Fischer AS, et al. Cannabis and the developing adolescent brain. Curr Treat Options Psychiatry 2020;7(2):144-161.
- PRSC Cannabis Concentration Workgroup. Cannabis Concentration and Health Risks: A Report for the Washington State Prevention Research Subcommittee (PRSC). Seattle, WA: University of Washington, 2020.
- Meier MH, et al. Persistent cannabis users show neuropsychological decline from childhood to midlife. Proc Natl Acad Sci U S A 2012;109(40):E2657-E2664.
- APA. Diagnostic and Statistical Manual of Mental Disorders (5th ed.). American Psychiatric Association, 2013.
- NIDA. Cannabis (Marijuana) Research Report: Is marijuana addictive? National Institute on Drug Abuse, 2021.
- NIMH, NIH. Understanding Psychosis. National Institute on Mental Health, 2023.
- Power E, et al. Intelligence quotient decline following frequent or dependent cannabis use in youth: A systematic review and meta-analysis of longitudinal studies. Psychol Med 2021;51(2):194-200.
Authored by Lexi Nims, Cannabis Education & Research Program (CERP). Last updated August 2023.