Mental health disorders among young people have risen nearly 50 per cent in the past 15 years. We go inside a teen brain to show how modern pressures impact the adolescent mind and where it can go wrong.
Meet Ruby.
She’s about to turn thirteen.
She loves Taylor Swift, Japanese anime and POV (point-of-view) videos on Tiktok.
The ABC has created her based on interviews with experts in youth mental health.
Ruby has hit puberty.
According to neuroscience, her brain is about to undergo major changes on her journey to becoming an adult.
At the start of puberty, the part of Ruby's brain used for rational thought — the frontal lobe — has reached its maximum size.
Within the frontal lobe is an area called the prefrontal cortex.
It's made up of a series connections of the brain's nerve cells, called neurons.
Thoughts and impulses travel along these cells. They connect via synapses.
Neuroscientist Professor Stephen Wood says the key task of the brain during adolescence is to cull many of the connections in the prefrontal cortex — it's called "synaptic pruning".
The remaining pathways will get more solidified and start to shape her personality.
"It essentially means the part of the brain used for rational thought is undergoing major change," he says.
"It's a period when a lot of things are changing. Your thinking patterns are more vulnerable.
"This explains why teens sometimes don't think through the consequences of their behaviour, especially around their peers," he says.
Then come hormones.
Ruby's body is releasing a flood of hormones including progesterone and oestrogen.
These kick off the usual series of biological changes like breast development and menstruation.
Professor Bronwyn Graham, from the University of NSW, says oestrogen also works on areas of the brain that dictate behaviour in both boys and girls.
A terrible secret
The thing about Ruby is she's harbouring a terrible secret.
Like one in three Australian girls, she was sexually abused as a child.
It's because of this trauma Ruby's brain is already likely very different to her peers.
Professor Wood says studies have shown adults who went through trauma or maltreatment as a child, like sexual abuse or neglect, show different patterns of brain function in MRI scans.
This image is based on a 2016 study and shows how a typical brain would fire in the area responsible for emotional regulation and impulse control.
This next image shows how the brain of someone maltreated as a child fires.
As you can see there's a lot less happening in an area that's supposed to moderate impulses.
"They don't necessarily function poorly, but they are different," Professor Wood says.
While this study looked at maltreatment like physical, sexual and emotional abuse, other academics say these kind of Adverse Childhood Experiences (ACEs) can also include bullying, family breakdown or exposure to natural disasters.
Professor Daniel Hermens from the University of Sunshine Coast says neuroscientists in the field have also found when children are exposed to verbal abuse the part of the brain that processes sound changes.
When they see a lot of family violence visual parts of the brain decrease.
"It's thought these differences are specific adaptations of the brain after repeated exposures, to reduce distress," he says.
Trauma is stressful
This kind of trauma is obviously stressful.
That's when the hypothalamus kicks in.
It's located deep in the centre of the brain.
When the body experiences stress it sends a message to the pituitary gland at the base of the skull.
The pituitary gland then sends a message to the adrenal glands, located on top of the kidneys, to release the stress hormone cortisol.
Eventually these levels rise to a point where the hypothalamus turns the tap off.
But under chronic stress this loop starts to get out of whack.
Professor Graham is a clinical psychologist who specialises in hormone function and says when the body is exposed to this hormone in the long-term it can interfere with hormones that trigger puberty.
She says children with traumatic childhoods are more likely to have early onset puberty.
She says this puts girls at higher risk of mental health problems for both hormonal reasons, and social factors, like being sexualised at a young age.
Conversely, boys who start puberty early have a better time.
"It's the boys who go later into adolescence who struggle because they may be physically smaller and more vulnerable to bullying," according to Professor Wood.
Stress contributes to anxiety
Ruby has started a new school and the girls keep whispering when Ruby walks past.
She can't work out why.
How Ruby interprets this will be decided by her brain structure and chemistry.
Her amygdala, which you can see in orange, is the primal part of the brain that controls her fight or flight response.
Neuroscientist Professor Daniel Hermens says long-term exposure to stress hormones also makes this part of the brain more sensitive to stress and hypervigilant to threat.
In this scenario Ruby's amygdala, which is already sensitive because of past trauma, is sending heightened threat signals.
Her still-underdeveloped frontal lobe, busy pruning all its synapses, can't yet moderate those thoughts and put them in context.
Timing also matters
Professor Graham says Ruby's oestrogen hormones are also working on this frontal lobe so when she's at the ovulation stage of her menstrual cycle, she's more likely to have a moderate response to this exchange and might take it in her stride.
If it happens just before her period, or during, she's more likely to interpret it poorly.
"Sex hormones oestrogen and progesterone are really important in helping us regulate our emotion," Professor Graham says.
"They're also important in helping us respond to threatening situations to temper down our initial fight or flight response."
Professor Graham says teens who are assigned female at birth experience high levels of oestrogen during ovulation and this makes them feel better compared with other times in their cycle.
In those assigned male, testosterone gets converted to oestrogen in the brain, so its impacts can be profound across the sexes.
And while most parents connect hormones with moodiness, many incorrectly think it's because of a spike in hormones when it's in fact because of a drop in those levels.
"In the week before and during menstruation we see things like increase in suicide attempts and poorer responses to treatment," Professor Graham says.
"Oestrogen is really important for mental health — anyone whose gone through perimenopause will tell you that."
Emotions run high
When Ruby gets home one day this text pops up on her phone.
Mid means beige for those playing at home. So naturally, Ruby is pretty upset.
Like many teens her brain has evolved so that during this phase of life her friendships are becoming more important than her family relationships.
Professor Wood says one of the earliest changes in the teen brain happens in the limbic system, which is responsible for emotion and memories.
It's right at the core of the brain and includes the hypothalamus, amygdala, thalamus and hippocampus.
"It gives teens a heightened sensitivity to emotions and changes the way they experience emotions," he says.
Ruby's mum has been stressed with a new job. The rising cost-of-living is also adding to pressures.
Last week, when Ruby asked for new designer shoes she turned to Ruby and said, "Why are you always making things harder?".
Ruby's always been a bit more sensitive.
Professor Wood says now she's a teenager this underlying personality trait might mean she reacts to this more than other teens might.
Her traumatised brain can't deal with such big emotions, and without enough impulse control, she throws a bowl at the wall.
It's not all bad
The limbic system also works in conjunction with the reward system of the brain.
It's made up of the nucleus accumbens (in blue), the ventral tegmental area (in yellow) and ventral striatum (green).
It undergoes a transformation during puberty that means that teens find pleasurable things more enjoyable than ever.
Consequently, they get an amazing rush from exciting or risky activities.
"This explains why teens love everything from horror movies to rollercoasters," Professor Wood says.
Ruby's been having trouble making friends at her school but there's one girl in Ruby's art class who she gets along with.
In truth, she's a little obsessed with her and Ruby doesn't know what to do with those feelings.
This update to the brain's rewards system means teens also take more pleasure in their friendships.
"Interactions with peers are a kind of social reward," Professor Wood says.
"This may explain why teens are so much more sensitive to peer rejection."
Music sounds better too
When Ruby puts Taylor Swift on she plays one particular song on repeat.
Professor Wood says this is no accident either.
The changes in the limbic system explain why teens commonly develop an intensity of interest during this period, whether it be Taylor Swift, playing guitar or even a classmate.
"There's all these studies showing that young people will go for the short-term reward and the limbic system lights up," Professor Hermens says.
Temptation can be too great
Ruby is spending lunch times alone.
Ruby hides in the toilets and one day spots a vape on the ground. She picks it up and smokes it.
A teenager's use of drugs, alcohol and even vapes also has some explanation in the brain as well.
The reward system of the brain is also the one that releases the happy hormone, dopamine.
Some teens get up to a seven-fold increase in dopamine activity during adolescence, the highest in their life.
And with their frontal lobe still developing, this sensible moderator in the brain is less likely to pump the brakes when it comes to risky things, especially around peers.
Professor Wood says with the reward system now seeking pleasurable sensations and a general undeveloped sense of impulse control, teens are more likely to try substances.
On the weekends, Ruby's dad is on shift and her mum spends most of the time cleaning or on her phone.
Ruby stays in her room and watches or reads anime. She can lose hours in POV videos.
Sometimes she posts her anime pictures. One got 1,100 likes. But she hasn't been able to replicate it.
The little hit she got from those likes would have been felt in the rewards system, or pleasure centre, of the brain.
In teens the heightened experience of pleasure likely means they get more of a boost from social media "likes" than their parents.
"Dopamine is about motivation and reward – it's reward-seeking behaviour. They're looking for new experiences all the time and that dopamine is going off," Professor Hermens says.
Sleep is a big deal
Ruby is starting to struggle to sleep.
She's just about to drift off when her phone pings. The text is from a fake account.
It's not the first one she's received.
She's being bullied at school and it's starting to impact a good night's rest.
Professor Hermens says emerging science suggests that it's at night when a process called glymphatic cleaning happens.
This is when brain and spinal fluid flushes the brain and cleans out the by-products from a day of processing thoughts.
This image shows an influx of brain and spinal fluid (in red) into the brains of mice while they're asleep.
"During adolescence the brain is producing more waste far more than any time in their life, which may explain why teens need more sleep," Professor Hermens says.
Depression takes many forms
When Ruby is at her lowest she doesn't see the point of anything and has lost interest in her passions like anime.
Neuroscientists say depression is a blunt description for a variety of problems that can happen in the brain.
In Ruby's case, the medical term is anhedonia which is an inability to take pleasure in things. It usually affects the reward systems of the brain.
It's a sign her anxiety has turned into depression.
Professor Hermens says in young people depression can also show itself as irritability, which explains some of Ruby's earlier outbursts.
"In young people anxiety often transitions into depression," he said.
At other times Ruby can just lay on her bed and sleep.
This fatigue is another common sign of depression in teens, according to Professor Wood.
"It's a big one, not getting out of bed. It's the brain being chronically stressed," he said.
"It's basically damaging the brain, reducing the connections, reducing neurons — atrophy.
"The longer that happens the worse it gets, it's a vicious circle.
"But teens also sleep a lot naturally and how you tell as a parent is very tricky."
This also may be why different types of depression respond to different therapies such as talking, cognitive behaviour therapy or medication.
Finding a way through
At school on Monday the school counsellor approaches Ruby.
She's noticed Ruby on her own a lot and invites her in.
So why has it all gone wrong for Ruby?
Professor Hermens says there's never one reason.
Her childhood trauma is one — especially if it wasn't dealt with at the time.
Girls, neurodivergent teens and queer adolescents are among those more likely to have mental health concerns.
"A lot of mental disorders are genetic or run in the family. You can have intergenerational trauma or learned behaviours," Professor Hermens says.
It's clear social pressures like bullying and her parents being busy and stressed are also exacerbating problems.
After a lot of work and help from her parents Ruby starts to get better.
Professor Hermens says the changes neuroscientists observe in the brain may only persist if they're left untreated.
"The good thing about younger brains is that while they're more vulnerable they're also more capable of change and recovery".
Paediatrician Professor Harriet Hiscock says it begins by talking to teenagers to find out what's wrong.
She suggests helping unpack what's going on in their mind and body and workshop potential responses.
"That makes it less frightening," she said.
"The fact they have really big emotions is a part of adolescence."
Like it or loathe it, Professor Hermens says exercise is really helpful and "is like fertiliser for the brain".
"It promotes brain-derived neurotrophic factor (pictured) which helps keep neurons alive."
Getting enough sleep and eating well also help promote brain health.
"Healthy brain equals healthy mind," he says.
Online treatment courses run by universities like The BRAVE Program and The Cool Kids Program are helpful, Professor Hiscock says, as are resources like Kids Helpline and school counsellors.
"Acknowledge teens, say, 'That's really tough', and ask if they want to keep talking, look at some online resources, talk to a psychologist or go to your GP for a mental health care plan."
Professor Wood, who is head of clinical neuroscience at youth mental health organisation Orygen, says parents can generally help support teens through adolescence with these four things:
- Careful monitoring
- Parents modelling values
- Connectedness
- Developing an outside interest with peers
The good news, Professor Wood says, is there is evidence that mild to moderate episodes of depression and anxiety can be confined to adolescence.
"The feelings are normal and often transient – what you need is good social support, not necessarily medical help."
All advice in the article is general and shouldn't replace proper medical advice.
Credits
- Reporter and digital production: Alison Branley
- Artwork: Lindsay Dunbar
