White and mixed-race girls were the most likely to report feelings of depression (25 percent), whereas black African girls were the least (10 percent). In boys, those with a mixed-race or "other" background were the most likely to reveal depressive symptoms (15 percent) and those with a Bangladeshi or Indian background least (less than 5 percent).
The researchers also found that girls from higher-income families were less likely to describe feelings of depression than their peers from lower-income families. Bucking the trend were girls from the poorest 20 percent of families, who reported less depressive symptoms than those from the second and third quintile income brackets.
In both the above cases, it is not obvious whether there are significant differences in the rate of depression among different groups or if some are more likely to report it than others.
This information was collected from the Millenium Cohort Study, a project that follows the lives of over 19,000 children in the UK who were born around the turn of the millennia. Researchers have been keeping tabs on their mental health since they were three, asking parents to complete a survey every few years.
When they were 14 years old, researchers also asked the teenagers themselves how often they agreed with a series of statements, including "I felt miserable or unhappy", "I felt I was no good anymore" or "I was a bad person".
This is a particularly crucial time in a person's mental development, the authors note. “Half of all cases of adult mental illness start by the age of 14, meaning prevention and early support for children is vital.”
While the results are extremely useful in showing the disturbingly high level of depression among teens today (and girls in particular), more is needed to better understand the reasons behind the trend and explain its consequences.