An American study of 615 adolescents found that adolescent girls worry about a wide range of issues, including their looks, friends and family, personal problems and romantic relationships.

In contrast the only thing adolescent boys worried about more than girls was succeeding in sport.

Gender differences

The researchers believe this could be part of the reason why, by the age of 18, the depression rate among females is twice as high as that among males.

Before the age of 11, girls and boys have more or less equal rates of depressive symptoms and depressive disorders.

However, between ages 11 and 15, girls' rates of depression rise steeply while those for boys increase only slightly.

Females brood

It is well established that rumination - the passive, repetitive focus on negative emotions - is more common in adult women than men when distressed. This appears to contribute to gender differences in adult depression.

The researchers believe the new study demonstrates that the ruminative style is adopted by girls as young as 11 years.

"Girls feel less control of their environments than boys from a very early age, and this sense of uncontrollability contributes to rumination," the researchers claimed.

"In essence, girls are frantically trying to understand what's going on in their lives and their own emotional distress, and this is manifested as rumination."

Many problems

Adolescents were asked to rate how much they worried about several issues on a scale from 1 (sometimes) to 3 (always).

Girls were found to worry more than boys about appearance, friends, personal problems, romantic relationships, problems with family, what kind of person they are, being liked by other kids and being safe.

The only issue that boys reported being more concerned about than girls was "sports and other activities."

The researchers said: "Girls' concerns are excellent fodder for rumination.

"These are not easily solved issues. Many of these issues involve others and one's relationships with others or the problems of others that are not easy to fix and can present new challenges or concerns every day."

Girls under pressure

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Professor Leslie Francis, a psychologist at Trinity College, Carmarthen, said girls were probably biologically more prone to depression.

But he said: "The cultural pressures put on adolescent girls is different to that put on adolescent boys.

"Adolescent girls are subject to a benign influence from ther peers, but also a more manipulative influence from the media and commerce. Concerns such as self worth and looks are easy to exploit if you have got something to sell."