Scientists have linked early puberty to an increased risk of self-harm.
Previous studies have suggested girls who start their period younger than the average age of 11 may be more likely to intentionally injure themselves.
With the early puberty risk among boys being less clear, scientists from the University of Bristol looked at both sexes.
After analysing more than 5,000 people in their early twenties, the team found men who experienced a growth spurt – a key sign of puberty – before the average age of 13.5 were up to 28% more likely to have self-harmed at 16 years old.
Among the women, those who shot up in height before 11.8 years old were up to 15% more likely to have intentionally injured themselves.
“Our study is the first to investigate the relationship between the timing of puberty and self-harm using an objective measure of pubertal timing in boys,” said lead author Elystan Roberts.
“There’s evidence self-harm is becoming more common in young people, so it’s important to identify the factors associated with self-harm so we can provide help earlier to those people who may be most at risk.
“We still don’t know a lot about the psychological effects of early puberty in boys because male pubertal timing is so hard to measure, so our results will be important for helping to reduce self-harm risk in boys as well as girls.”
While previous research has flagged early puberty as a risk factor for self-harm in girls, participants were often asked to recall when they started experiencing symptoms compared to their friends.
To more accurately assess the age of puberty, the Bristol scientists analysed data on so-called peak height velocity from participants of the Children of the 90s study – in other words how old the teens were when they experienced a growth spurt.
From the age a girl starts her period, most grow between 5cm (1.9 inches) and 7.5cm (2.9 inches) annually over the next year or two, before reaching their adult height.
Boys generally gain an average of 7cm (2.7 inches) to 8cm (3.1 inches) in height a year during puberty.
Watch: Starting university during pandemic impacting mental health
The scientists calculated the average age of peak height velocity among the participants as 13.5 years in boys and 11.8 years in girls.
The participants then completed self-harm surveys at 16 and 21 years old.
Results – published in the journal Epidemiology & Psychiatric Sciences – revealed self-harm at 16 years old was highest among the men and women with an early peak height velocity.
For the male participants, experiencing peak height velocity one year before the average age was linked to a 28% greater risk of self-harm.
Among the females, the odds rose by 15%.
The scientists hope their results will enable medics to identify patients who may be at risk of self-harm, allowing them to intervene early.
“The next steps will be to identify the mechanisms that explain the association,” said co-author Dr Becky Mars.
“This might be biological factors like neurological development or hormone changes, or it might be psychosocial factors like bullying, substance use or depression.
“Once we have a better understanding of the reasons why early developers are more likely to self-harm, interventions can be designed and delivered to help reduce self-harm risk.”
How to avoid self-harm and the help available
Talking to a trusted loved one about how you are feeling could help ward off self-harm. Some people also benefit from confiding in trained volunteers, like The Samaritans.
People who are considering or carrying out self-harm should also contact their GP for help.
A doctor may be able to work out if certain emotions are leading to self-harm, like sadness or anxiety, which can be expressed another way.
For those about to self-harm, NHS advice suggests you try distracting yourself by going for a walk, listening to music, carrying out calming breathing exercises or doing something harmless that interests you. The desire to self-harm may pass over time.
If you feel unable to discuss your emotions, try writing them down in a note, which no one else need read.
For confidential emotional support at times of distress, contact The Samaritans at any time by calling 116 123 or emailing email@example.com.
People can also text “SHOUT” to 85258 to contact the Shout Crisis Text Line or text “YM” if they are under 19.
For those who prefer webchat, Self Injury Support webchat is open Tuesdays, Wednesdays and Thursdays from 7pm to 9.30pm for women and girls only.
For men, CALM webchat is open from 5pm to midnight every day.
Watch: Up to 10 million Britons may need mental health support after pandemic