Cannabis and mental health

How cannabis can affect mental health and brain function.

On this page

• Risks to mental health
• Risks to brain function
• Lower your risk
• Related links
• References

Risks to mental health

If you use cannabis socially, to relax, or to cope with poor mental health, it's important to understand the long-term risks. These are some of the ways daily or near daily cannabis use can affect your mental health.

Developing anxiety and depression

Daily or near daily cannabis use over time can increase your chances of developing disorders related to anxiety and depression. Long-term daily or near daily use can also negatively impact your brain's dopamine system, which gives you feelings of pleasure and joy. This can make you feel:

• fatigued
• low in mood
• unmotivated

Worsening anxiety and depression

Some people use cannabis to provide relief from stress or from feeling anxious or depressed. However, cannabis use has not been found to improve mental health over time. Daily or near daily cannabis use actually contributes to poor mental health, and if you use cannabis this frequently you could:

• become dependent on cannabis
• have trouble regulating your emotions
• experience anxiety and depression more often

You're more likely to recover from long-term anxiety and depression if you reduce or stop using cannabis.

Cannabis dependency

You can become dependent on cannabis over time, just like you can with other drugs, alcohol and tobacco. Symptoms can include:

• craving cannabis
• thinking a lot about cannabis
• finding it hard to stop or reduce use
• feeling like you need to use cannabis
• an increased tolerance to cannabis
• feeling increasingly restless, moody or anxious when not using cannabis

Psychosis and schizophrenia

Psychosis is a temporary mental state that can involve severe paranoia and hearing or seeing things that are not real. Schizophrenia is a longer-term form of psychosis that requires life-long treatment, and includes symptoms like:

• paranoia
• hallucinations
• disordered thinking, speech and behaviour

In severe cases, daily or near daily cannabis use can increase your chance of experiencing psychosis and schizophrenia. These cases are more likely among people with a personal or family history of mental health disorders, particularly male teenagers and young adults.

Risks to brain function

Daily or near daily cannabis use can harm your short and long-term memory, thought patterns, focus and speech. You may:

• have trouble remembering what you just thought or said
• think unusual or abnormal thoughts
• become distracted or have trouble concentrating
• have trouble forming sentences or experience delayed speech

These effects can be frustrating and distressing, especially if it impacts your:

• self-image
• performance at work or school
• relationships with family and friends

Reducing or stopping cannabis use can reverse some or all of its effects, and can help improve your long-term mental health and brain function. Everyone's response to cannabis and their response to reducing or stopping cannabis can differ. Seeking support from a loved one or a healthcare professional can help.

Lower your risk

Avoid daily or near daily use. The effects on your mental health and brain function over time are greatest if you use cannabis this frequently.

Delay using cannabis. Cannabis can interfere with brain development until around the age of 25. If you're an adolescent or a young adult, your mental health and brain function are at greater risk of harm.

Choose products with lower levels of THC. The higher the THC content of a product, the more likely you are to experience harms related to mental health and brain function. Any product with over 10% or 10mg of THC is considered high.

Avoid combining cannabis with alcohol or other substances. Using cannabis at the same time as alcohol or other substances further increases the risks to your mental health and brain function.

Avoid cannabis if you have a personal or family history of mental health disorders. You're at higher risk if you have a family history of:

• psychosis
• schizophrenia
• substance dependence

Avoid inhalable products. You're more likely to use and become dependent on cannabis if you smoke or vape than if you use non-inhalable products like:

• oils
• edibles
• capsules

Check in with yourself. Take some time to reflect on your cannabis use and evaluate your relationship with cannabis. Reducing or stopping daily or near-daily use can be difficult to do on your own. Talk to someone you trust if you need help, such as a:

• friend
• counsellor
• family member
• healthcare professional

Related links

• Addiction to cannabis
• Get help with substance use
• Reduce your risk: Choose legal cannabis
• Knowing Your Limits with Cannabis: A Practical Guide to Assessing Your Cannabis Use (Canadian Centre on Substance Use and Addiction)
• Drug impaired driving

References

For more information on how cannabis can affect mental health and brain function, consult the references below.

Mental health

Effects on anxiety and depression

• Cannabis and mental illness: a review
• Effects of extended cannabis abstinence in major depressive disorder
• Cannabis and emotion processing: A review of behavioral, physiological, and neural responses
• Molecular brain differences and cannabis involvement: A systematic review of positron emission tomography studies
• Serious psychological distress and daily cannabis use, 2008 to 2016: Potential implications for mental health?
• The association between cannabis use and anxiety disorders: Results from a population-based representative sample
• Cannabinoids for the treatment of mental disorders and symptoms of mental disorders: a systematic review and meta-analysis
• Reductions in cannabis use are associated with improvements in anxiety, depression, and sleep quality, but not quality of life
• Association of cannabis with long-term clinical symptoms in anxiety and mood disorders: A systematic review of prospective studies
• Canadian Network for Mood and Anxiety Treatments (CANMAT) Task Force Report: A Systematic Review and Recommendations of Cannabis use in Bipolar Disorder and Major Depressive Disorder

Cannabis dependency

• Cannabis use and cannabis use disorder
• Psychological distress, cannabis use frequency, and cannabis use disorder among US adults in 2020
• What is the prevalence and risk of cannabis use disorders among people who use cannabis? A systematic review and meta-analysis

Psychosis and schizophrenia

• Rates and correlates of cannabis-associated psychotic symptoms in over 230,000 people who use cannabis
• Association of cannabis use-related predictor variables and self-reported psychotic disorders: U.S. adults, 2001-2002 and 2012-2013
• Annual incidence of cannabis-induced psychosis, other substance-induced psychoses and dually diagnosed schizophrenia and cannabis use disorder in Denmark from 1994 to 2016

Brain function

• Adults with a history of recreational cannabis use have altered speech production
• Association between formal thought disorder and cannabis use: a systematic review and meta-analysis
• Cognitive outcomes associated with long-term, regular, recreational cannabis use in adults: A meta-analysis
• Evidence on the acute and residual neurocognitive effects of cannabis use in adolescents and adults: a systematic meta-review of meta-analyses

Effects of reducing or stopping cannabis use

• Effects of 28 days of cannabis abstinence on cognition in major depressive disorder: A pilot study
• Impact of 2 weeks of monitored abstinence on cognition in adolescent and young adult cannabis users
• One month of cannabis abstinence in adolescents and young adults is associated with improved memory

Lowering risk

• Prevalence and correlates of cannabis use disorder among Australians using cannabis products to treat a medical condition
• Lower-Risk Cannabis Use Guidelines (LRCUG) for reducing health harms from non-medical cannabis use: A comprehensive evidence and recommendations update
• Differences in those who prefer smoking cannabis to other consumption forms for mental health: what can be learned to promote safer methods of consumption?