Questions Answered

Here are some of the most commonly asked questions answered by the experts: scientists, and those who’ve experienced first hand the impact of cannabis use and psychosis

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YES. Cannabis is linked to psychosis as one of the factors associated with developing a psychotic disorder.

The jury is no longer out. We now have substantial evidence that regular cannabis use in adolescence increases the risk of developing psychosis.

The risk with use varies from an estimated 4x to 12x depending on factors such as family history of mental illness, age at which cannabis use starts and THC content of the cannabis.

Specifically, regular cannabis use in adolescence:

  1. is linked the development of a chronic life-long psychotic disorder in at-risk individuals.
  2. is associated with an earlier age of onset of psychosis.
  3. can complicate and/or prevent recovery in individuals already diagnosed with a psychotic disorder.

research saysYouth voice

I'm still not sure what caused what, but I wish I had more information.

It triggered it. Because I was smoking a lot of it several times a day and hearing stuff... I hallucinated right after smoking.

I couldn't tell whether it was the weed that did it, or was it my brain that was affected… and the weed was a trigger

I think smoking pot increases symptoms in people with mental disorders and those who don't have mental disorders – if there's any trace of it in their family history it can make it go "boom".

Psychotic symptoms starting happening and I heard radio messages and voices in my head and then I stopped and haven't smoked since.

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Possibly you. We have no way at present to identify who will have a mental health crisis with cannabis use.

Research has shown that cannabis use impacts psychosis. Cannabis use impacts age of onset and the development of psychosis.

People who use cannabis in their early teenage years (<age 15) are at greater risk of developing psychosis, at a younger age, and later in life.

Cannabis use has been shown to trigger and worsen psychosis in some young people. They are also likely to experience their first symptoms at a younger age.

The earliest onset is associated with higher THC “skunk” cannabis strains; an average of 6 years earlier onset. This association is so strong that it may be to blame for London, England having one of the highest rates of psychosis incidence in the world.

Overall, this knowledge has led to the development of lower risk cannabis use guidelines that strongly suggest starting cannabis use later in life.

research saysYouth voice

I think it could play a role to speed up the things that happened – psychosis, definitely. I think it triggers for some people susceptible, but not necessarily all people.

I think there definitely is a link between psychosis and any type of drug use including marijuana. Because it makes you hallucinate. It intensifies existing hallucinations and thoughts and then creates a mass amount of anxiety.

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We only have a short list of currently known risk factors such as starting cannabis use before age 15, having a relative with a mental illness increases your risk, and use of high THC cannabis strains.

Unfortunately, we cannot tell who is who is at risk of developing psychosis if they use cannabis but we do have several risk factors that we can name.

  • The age at which cannabis use is started in one of these factors with below age 15 being especially dangerous.
  • The amount of THC in the cannabis
  • The balance of CBD and THC in cannabis


research saysYouth voice

If I had not started smoking marijuana I would never have known I had psychosis… it would never have come out. Because it was technically the drug that was causing me to have psychotic symptoms.

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Psychosis is a mental state in which you lose touch with reality.

Psychosis is a break with reality characterized by hallucinations, false beliefs (delusions), impaired thinking and lack of motivation.

For more information about psychosis, please see the facts section.

research saysYouth voice

It was chaotic, my thinking was scattered when I smoked and I had a lot of bizarre thoughts. Some of the stuff like how to control other people through thoughts… got really paranoid I would go too in depth with it on my own away from my friends.

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There are several types of motivation for cannabis use. People use for different reasons at different times.

The reasons for using cannabis vary from individual to individual and even use to use; but we have some categories for the various motivations for using cannabis.

Enhancement motives can be thought of as adding excitement to your life. This is often a motivation for recreational drug use.
Social motives are those that cause you to indulge in a behavior to help you enjoy a party for instance.

Conformity as the word implies is acting to be like your peers.

Coping is a motive that is often applied to cannabis use in relation to psychosis. This motive relates to people using to help cope with stress and anxiety.

Routine is an additional category of motive and we often think of this motive as the one people can avoid if they have activities and interests in their lives. This motive is cited when people use out of boredom.

There has been some research done on motivations to use cannabis. There has been a systematic review (a large formal review of the literature joining that gives an overview of the results from different studies) done looking at motives for cannabis use. This overview suggested that early onset of use (11-15 years of age), regular use that was not related to social motives and use to cope with stressful life events were all risk factors for developing a cannabis use disorder.

Conformity motives predicted use but not dependence. Coping may be a motive more often used by women when deciding to use cannabis. While routine and conformity are often motives for men to use cannabis. Additionally, there are studies that suggest having a mental illness might be a risk factor for developing a cannabis use disorder but these were mixed. This makes it unclear if people use cannabis to self-medicate in relation to their mental disorder.

research saysYouth voice

It’s fun and disorienting like the most insane rollercoaster I’ve ever been on.

It helps me relax – a lot – it makes me carefree – like nothing matters except for the moment…. I’m not used to living like that. It puts me in that state.

I wanted to... all my friends tried it before me. I was the only one who hadn’t…

At first it took away the pain and depression then it all just back tracked - it instantly starting causing pain and depressed feelings.

I've never tried it because I don't like the smell. I was worried about my health, and I was into school and sports and I didn't feel pressure to do it. I was drawn to a different crowd.

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Although there is a lot of information out there about the different properties of Sativa vs. Indica, scientifically (and legally), there is no difference between these two types of cannabis plants. And all cannabis plants are considered to be Cannabis Sativa L.

They were originally different strains of cannabis that came from different regions of the world. However, due to years of interbreeding, cannabis species have cross-pollinated, and studies have shown that there is no longer a difference in plant genetics between plants labeled Indica versus plants labeled Sativa. The existence of different species of cannabis and how many there are is currently under dispute.

What about THC and CBD?

Just knowing whether cannabis is sativa or indica won’t tell you much about the effect it might have when used. There are many other significant characteristics and differences between different types of pot, especially when it comes to THC and CBD content. High THC cannabis refers to strains with greater than 15% THC, and these are becoming more common in Canada. THC is the compound that mostly gives you the “high”.

However, for the developing brain these are the strains that are potentially the most damaging as they overwhelm your body’s internal cannabinoid system, which is busy making sure your brain regions connect correctly. Also these higher THC strains are associated with a higher risk of developing psychosis even without a family history.

These high THC strains are also usually low in CBD. CBD is known as the neuroprotective component in the cannabis plant. In previous decades there was a balance between the ratio of THC:CBD, this is why older research suggests cannabis use is less risky for mental health. High CBD strains are often used in medical marijuana patients as they have less of the high and more of the potential medical benefits.

While the safest approach for youth is to wait to try cannabis, if you are considering using or have been using, a less-risky approach is to use a lower THC strain (8% or below) with an equal % of CBD. These would be similar to the strains in the 2000s and earlier and we know from research done then that the risk of developing psychosis is still there but it is 2-4x rather than 8-12x.

Also research done in 2000s and before would suggest that there is also less impact on anxiety and depression with these strains of weed. However, we do not know if there will be permanent changes done to your developing brain structure even with use of these strains. More research needs to be done.

research saysYouth voice

When I switched from a high THC to a high CBD strain, it made a big difference.

It was helpful for me to learn about different strains and how they affected my psychosis.

Changing my weed habits was hard but it really helped in my recovery.

The more info I had, the more I felt empowered to make my own choices.

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A “bad trip” has some of the features of a psychotic episode.

How can you know if you’re experiencing psychosis or just a bad high? It can be difficult to distinguish the difference because a bad trip that can occur when smoking cannabis has some of the same symptoms as a psychotic break. Cannabis use can cause a temporary psychotic episode in some people.

You may know someone who has had a bad trip. Unfortunately, we now know that those who have had a bad trip on cannabis are at high risk for developing a psychotic disorder, which is a chronic condition such as schizophrenia.


research saysYouth voice

It intensified existing hallucinations and thoughts, and then creates a mass amount of anxiety.

I feel like people are coming after me, really paranoid.

I never realized it was psychosis, started getting paranoid when I started smoking weed… I didn't realize until later and connected the dots.

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Yes, cannabis is addictive.

Cannabis use can cause addiction in some people. In the same way that not everyone who has a drink becomes addicted to alcohol, not everyone who uses cannabis will become dependent.

People sometimes point to scales of addiction and use the lower addictive potential of cannabis as proof of how cannabis is unlikely to cause addiction. However, on these scales cannabis is usually ranked with coffee for addictive potential. How many people do you know that have to have their morning cup of coffee or get a withdrawal headache?

Individuals who are dependent on cannabis will also experience withdrawal symptoms when they stop using such as anxiety, a strong sense of uneasiness, sleep disturbances, irritability, loss of appetite and in some cases, aggressive behavior.

People who are dependent on cannabis have what is called a cannabis use disorder. This disorder may affect up to 30% of cannabis users. We do know that younger age of starting cannabis use and use of high THC (also known as high potency) cannabis can increase the risk for developing a cannabis use disorder.

Unfortunately, we do not currently have effective treatments for cannabis use disorders.

research saysYouth voice

In the beginning it was if friends had it… to buying… to once in awhile… to once to twice a week… to everyday then to several times a day.

I was smoking weed all day everyday to deal with my problems instead of dealing with them in real life.

At the same time I don’t like how it makes me feel afterwards even if it cheers me up. I lose my motivation for the day, kinda similar to a hangover… I go through ups and downs, I feel pretty good, laughing, having a good time… then I start worrying about things and I get tired too.

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Cannabis binds to receptors in the brain to give the high that people experience. Unfortunately, this binding action may overrule the natural function of these receptors.

Why does cannabis use affect mental health especially if you start using as a teenager? The answer is tied to brain development. Your brain develops from birth up to about age 25. The brain develops in stages- basically from the more ancient parts of the brain, closer to the back of the head (such as those areas that control breathing) towards the front with your prefrontal lobe (the very front of the cortex), which develops last.

This region of your brain is most involved in your personality, decision making and social behavior. You have cannabinoid molecules that your body makes to perform biological functions within you. In the developing brain, the receptors that bind these biological cannabinoids are used to guide brain cells to make the correct connections needed for healthy brain function.

Plant cannabinoids such as THC and CBD bind to these same receptors and research suggests that the large amount of signal that comes from inhaling or ingesting weed overwhelms the normal brain development process.

The reason adults over 25 are not at the same risk is that these cannabinoid receptors have done their job finishing brain development and then research suggests that this function is turned off by the cannabinoid receptors changing their pattern of expression (where in the brain the receptors exist).

research saysYouth voice

Smoking made me feel better in the moment, but I’m pretty sure it made things worse over time.


We’re finding that pot use seems to change over time, and people start for different reasons. I cant believe how early some people start smoking pot! The most common response is 12 years old!

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Cannabis affects men and women differently such as women store THC in their bodies for longer.

Did you know that there are sex differences in how we react to cannabis? It is well known from drug use surveys that males tend to use more recreational drugs than females. Unfortunately, this may be masking some troubling trends that are being newly researched. In early psychosis, females usually have a later age of onset than males, and female cannabis users may develop earlier onset psychosis with cannabis use.

There is also evidence that females who use cannabis may be less likely to quit and they report a lower quality of life than male cannabis users. More research needs to be done on this topic. While there are gender differences that may exist with cannabis use and psychosis there is no evidence for socioeconomic or ethnic differences.

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Cannabis use can impair recovery and treatment options if you already have a mental illness.

What about use in people who have already been diagnosed with a psychotic disorder? Ongoing cannabis use in people with psychotic disorders has been shown to be associated with more frequent relapses, more frequent hospitalizations, and greater positive symptoms in users compared to non-users with psychosis.

Besides the link with psychosis, there is increasing evidence that using cannabis can also impact mental health in other ways.

Our current understanding is that cannabis use can increase the risk for depression and some forms of anxiety disorder.

Overall, the literature shows that cannabis use is positively associated with symptoms of depression and, when begun in adolescence, can increase the risk of developing depression.

Cannabis use in adolescence may also increase the risk of suicide. A meta-analysis, which combines data from 14 different studies, demonstrated that cannabis use at early ages, particularly heavy use, was associated with an increased risk of depression. In a current market with higher THC content, less cannabis may be needed to develop the same level of risk.

research saysYouth voice

I quit because it was making me worse with the illness it’s hard to do good… to get my life back even without it.

If I smoke, ultimately doing it would make me so nervous… It’s fun and then it gets scary.

Smoking weed is fun. No doubt about it. It also takes away anxiety and depression. But what I didn’t know is that weed causes anxiety and depression. Not to mention psychosis, paranoia, and other nasty stuff. It’s a terrible cycle, but if we can fight the cycle and get treatment for the root of the problem, weed doesn’t seem as hard to get rid of, and we’ll be much better in the end.

If you smoke marijuana on certain medications it can cause a bad reaction and cause worse psychotic symptoms.

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If you are under the age of 25 or have been previously diagnosed with a mental illness, use cannabis with caution.

We now have substantial evidence for a link between cannabis use in adolescence and development of psychosis later in life.

Cannabis use can also have a negative impact on disease course in individuals already diagnosed with a psychotic disorder.

Starting cannabis after age 18 is associated with a lower risk of developing psychosis than starting by age 15. However, our best evidence is that waiting until your brain is fully developed (age 21 to 25) is your best defense against the risk of developing psychosis with cannabis use.

research saysYouth voice

If we knew then what we know now, we would have cut down or stopped smoking earlier.

Your peers and social group may pressure you to try marijuana and although it may seem like something new, fun or exciting to try out, there are negative effects. It smells and it isn’t good for your health. Your dependence on it may increase over time. What starts off as something to do with your friends may turn into an isolating or scary experience.

For most of us, it sometimes felt like marijuana worsened or even triggered our psychosis symptoms. A few of us have also found that it messes with our medications.

For some of us, marijuana masked our emerging psychosis symptoms. We thought they were just the effects of being high, and didn’t know that it was time to seek help