Female and gender-diverse teenagers are more likely to experience worsening mental health during high school than their male classmates.
A study of more than 6600 Australian teenagers tracked high school students from years 7 to 10, allowing researchers to study how mental health symptoms developed over time.
The findings suggest mental health symptoms are "alarmingly common" and increase as teenagers grow.
Nearly three in 10 teens had probable major depression, almost one in four reported high mental distress and nearly one in four had moderate-to-severe anxiety symptoms by year 10.
"While our sample wasn't representative, it provides further evidence that current generations of teenagers are suffering more than those before them," lead author Scarlett Smout said.
Females and gender-diverse teens experienced greater symptoms of distress, anxiety and depression, compared with males.
This was especially the case for those from less affluent backgrounds.
Experts say more research is needed to understand what was driving poor mental health among Australian teens as well as investment in prevention and support programs.
"Adolescent mental health is a hugely concerning and growing public health issue," Public Health Association of Australia chief executive Terry Slevin said.
"The teenage years are a foundational time in our children's lives, setting up their mental wellbeing for the future.
"This study shows that mental health symptoms in our younger generation are disturbingly common, deteriorate over time and are affecting some of the more vulnerable segments of our community."
Lifeline 13 11 14
Kids Helpline 1800 55 1800 (for people aged 5 to 25)
