D. Healthy Living · Healthy Living

Mental Health, Substance Use and the Growing Brain

D1.2 A1.2 A1.4 A1.6About 45 minutes

Learning goals

I can explain links between mental health problems and problematic substance use.
I can explain why cannabis use is a particular risk for the developing teen brain.
I can identify school and community resources for help with mental health and substance use.

Words to know

mental health problem
A time when a person's thoughts, feelings or behaviour are causing them distress and making daily life harder. It may or may not be a diagnosed mental illness.

problematic substance use
Using alcohol, cannabis, nicotine or other drugs in a way that causes harm to a person's health, relationships, school or safety.

self-medicating
Using a substance to try to cope with difficult feelings like stress, sadness or worry, instead of getting help.

addiction
When a person keeps using a substance (or doing a behaviour) even though it causes harm, and finds it very hard to stop.

THC
The chemical in cannabis that causes the "high". It affects the brain.

psychosis
A serious condition where a person loses touch with reality, for example seeing or hearing things that aren't there.

resource
A person, place or service that can help.

A two-way street

Sometimes a person who feels anxious, sad or stressed starts using alcohol, cannabis or vaping to feel better. And sometimes using those substances makes anxiety, sadness or stress worse. Mental health and substance use are linked in both directions.

Today you'll explore those links, learn why the teen brain is especially sensitive to cannabis, and map out who can help.

Remember from Grade 6

You learned the effects of cannabis, that THC causes the high, that edibles take a long time to work, and that the brain keeps developing until about the mid-20s. You also practised the decision-making process and the choice to abstain (not use). This year you'll connect substances to mental health.

How the links work

Mental health problem → substance use

Some people use substances to self-medicate: to escape worry, numb sadness, fall asleep, or fit in. It can seem to help for a short time, but it doesn't solve the problem underneath.

Substance use → mental health problem

Alcohol, cannabis and nicotine all act on the brain. They can:

make anxiety and low mood worse, especially when the effect wears off;
disrupt sleep, which affects mood and focus;
lead to addiction, where a person feels they need the substance to feel normal;
cause problems at school, with family and with friends, which adds stress.

This can turn into a cycle: feel bad → use → feel worse → use more.

Brain area or skill	Still developing in teens?	How cannabis (THC) can affect it
Memory and learning	Yes	Can make it harder to remember and learn; long-term, frequent use is linked to lasting problems with memory and concentration
Attention and focus	Yes	Harder to pay attention in class
Decision-making and impulse control (front of the brain)	Yes, until about the mid-20s	Judgement and reaction time are affected while high, raising the risk of accidents and risky choices
Mood	Yes	Can worsen anxiety and depression for some people
Sense of reality	Risk applies at any age	Can cause psychotic episodes (paranoia, hallucinations); regular use raises the risk of psychosis, especially for people with a family history of psychosis or schizophrenia

Why starting cannabis young is riskier. Health Canada says harms appear worse when people start early and use often.

The brain keeps developing until about the mid-20s. Ontario sets the minimum age for cannabis, alcohol, tobacco and vaping at 19, partly to protect developing brains.

Know the law

In Ontario, you must be 19 or older to buy, use, possess or grow recreational cannabis. The same minimum age, 19, applies to buying alcohol and tobacco and vaping products in Ontario. The ages are set this high partly to protect developing brains.

Where to find help

At school: a teacher you trust, guidance counsellor, child and youth worker, social worker, school nurse or principal.

In the community: your family doctor or nurse practitioner; community health centres; youth wellness hubs and youth mental health agencies; Elders and Indigenous health centres; faith leaders.

Phone, text and online (free, confidential):

Kids Help Phone: call 1-800-668-6868 or text CONNECT to 686868 (24/7).
9-8-8 Suicide Crisis Helpline: call or text 9-8-8 (24/7).
ConnexOntario: 1-866-531-2600 (24/7) for mental health, addiction and problem gambling services in Ontario.
Hope for Wellness Helpline: 1-855-242-3310 (24/7) for all Indigenous people in Canada.
Emergency: call 9-1-1.

Match the level of help to the situation. The more serious it is, the faster you bring in an adult or emergency help.

Worked example

Let's trace a cycle

Noah, 14, has been really anxious since moving to a new school. An older student offers him a vape and says, "It calms you down." After a few weeks, Noah feels jittery and irritable when he doesn't vape, and his anxiety seems worse.

Mental health → substance use: anxiety led Noah to try vaping to cope (self-medicating).
Substance use → mental health: nicotine is highly addictive. The irritability and jitters between vapes are signs of withdrawal, which can feel like more anxiety.
The cycle: anxious → vape → withdrawal → more anxious → vape more.
Breaking it: Noah can talk to a parent, his doctor or a school counsellor; get help to quit (a doctor can help); and learn other ways to manage anxiety, like breathing, exercise, and talking.

Noah's story shows the link in both directions, and that getting support is the way out of the cycle.

Worked example

Let's choose the right resource

Three situations: (A) Zara feels a bit stressed about exams. (B) Ben thinks his friend is using cannabis every day and skipping class. (C) A friend texts that they want to end their life.

A: Talk to a parent or teacher; use coping strategies; if it continues, see a school counsellor or call Kids Help Phone.
B: Talk to the friend with care ("I'm worried about you"), then tell a trusted adult, such as a counsellor. Kids Help Phone can also help Ben figure out how to support his friend.
C: This is an emergency. Tell an adult right away and call 9-1-1 if the friend is in immediate danger. 9-8-8 is the suicide crisis line (call or text). Never keep this a secret.

Match the level of help to the situation. When someone's safety is at risk, get an adult and emergency help immediately.

Hands-on activity

My help map

You need: paper and coloured pencils.

Draw yourself in the middle of the page.
In a circle around you, write the people you could talk to (family, friends, teacher, coach, Elder...).
In the next circle, write school resources (guidance counsellor, child and youth worker...) and find out their names and where their offices are.
In the outer circle, write community and phone resources with their numbers: Kids Help Phone, 9-8-8, ConnexOntario, your family doctor.
Save the numbers in your phone or put the map somewhere you'll see it.

What to look for: at least two names in each circle and correct phone numbers.

Your turn

Explain what self-medicating means.

Give one way a mental health problem can lead to substance use.

Give one way substance use can make mental health worse.

Until about what age does the brain keep developing?

Name two ways cannabis can affect the teen brain.

What is the legal age to buy cannabis in Ontario?

Name one school resource and one community resource for mental health or substance use help.

More practice: warm-up

True or false: substances solve the problems underneath stress or sadness.

What chemical in cannabis causes the high?

How can you reach Kids Help Phone by text?

What number do you call or text for the Suicide Crisis Helpline?

What is psychosis?

More practice: on your own

Why are the harms of cannabis greater for teens than for adults?

Explain how lack of sleep connects substance use and mental health.

Your friend says, "Cannabis is legal, so it can't hurt your brain." Respond with facts.

Why is ConnexOntario a good resource for a family?

What makes it hard for some teens to ask for help, and what can make it easier?

Challenge

Draw (or describe) the cycle between anxiety and substance use, then show two places it can be broken.

A Grade 7 student says, "It's just the occasional drink at parties; it doesn't affect mental health." Give a balanced, factual response.

Create a plan for what to do if you are worried about a friend's substance use. Include what to say, who to tell and what not to do.

Check your understanding

Quiz

Self-medicating means...

Which statement about mental health and substance use is true?

Why is cannabis especially risky for teens?

In Ontario, the minimum age to buy cannabis, alcohol and vaping products is...

To reach Kids Help Phone by text, you...

A friend texts that they want to end their life. What should you do first?

For parents and teachers

Big idea: This lesson covers the Grade 7 expectation to demonstrate an understanding of linkages between mental health problems and problematic substance use, as well as between brain development and cannabis use, and identify school and community resources that can provide support for mental health concerns relating to substance use (D1.2). It builds coping (A1.2), relationships (A1.4) and critical thinking (A1.6).

How to help at home:

Make the help map together and add your family doctor's number.
Share your family's expectations about substances clearly and calmly, and explain the reasons (health, law, brain development).
Ask, "What would you do if someone offered you a vape?" and practise responses.
Keep alcohol, cannabis and medications secured.

Facts used: In Ontario, the minimum age for recreational cannabis, alcohol, and tobacco and vaping products is 19. Helplines: Kids Help Phone 1-800-668-6868 / text CONNECT to 686868; 9-8-8 Suicide Crisis Helpline (call or text); ConnexOntario 1-866-531-2600; Hope for Wellness 1-855-242-3310. All are 24/7.

Common difficulties: Children may think "legal" means "safe", or may worry that asking for help will get a friend in trouble. Stress that safety comes first and that adults want to help.