Girls react differently to stress because it changes parts of their brain, new research suggests.
Traumatic situations causes the insula to shrink in girls, a study has found
However, pressure has the opposite effect on boys and makes theirs grow
Experts believe girls suffering from stress develop quicker than others
Traumatic situations cause the section of their brain responsible for feelings and actions - known as the insula - to shrink.
Whereas stress has the opposite effect on boys, causing theirs to grow.
Experts believe the response may speed up the aging process in girls exposed to stress when they are young - potentially triggering an early puberty.
Around 60 children aged nine to 17 with similar IQs underwent MRI scans in a study by researchers from Stanford University.
The brains of male and female patients suffering from post traumatic stress disorder (PTSD) were assessed.
It is usually triggered by accidents, violent personal attacks, sexual abuse and witnessing violent crimes and disasters.
Exposure to such events does not always cause PTSD – but those who do develop normally suffer nightmares and flashbacks.
Previous research has found girls were more likely to suffer from the anxiety disorders than boys – but until now scientists were unsure why.
Of these, 30 had trauma symptoms. Five experienced one episode of the disorder while the remaining 25 had two or more bouts.
The rest were part of a control group and there were no differences in the brain structure between boys and girls.
Trauma stress changed one part of the insula, a region of the brain that helps control feelings and actions, they found.
The size of the brain region was reduced in traumatized girls compared to females in the control group.
However, it appeared to have the opposite effect on boys - who had a larger insula than those without PTSD.
The insula usually shrinks in size as children and teenagers grow older, leading experts to believe traumatic stress could contribute to aging in girls.
Lead researcher Dr Victor Carrion said: 'The insula appears to play a key role in the development of PTSD
'The difference we saw between the brains of boys and girls who have experienced psychological trauma is important because it may help explain differences in trauma symptoms between sexes.'
Study co-author Dr Megan Klabunde said: 'There are some studies suggesting that high levels of stress could contribute to early puberty in girls.
'It is important that people who work with traumatized youth consider the sex differences
'Our findings suggest it is possible that boys and girls could exhibit different trauma symptoms and that they might benefit from different approaches to treatment.'
The study was published in the journal Depression and Anxiety.