New study: Girls’ mental health problems have tripled

A longitudinal study from Lund University in Sweden shows that mental health problems have increased sharply among lower secondary school students, becoming three times more common among girls over a period of 17 years.

In the first survey period (2007-2008), around 10 per cent of girls were above the limit for what is considered clinically significant mental health problems. In the second survey period (2024-2025), the corresponding figure was about 30 per cent - approximately three times higher.

The study confirms that mental health problems have become more common among girls. It also shows that boys have experienced an increase in mental health problems over the same period, but the rise among boys is less pronounced than in girls.

The researchers also found an increase in both repeated self-harm and disordered eating among girls. However, this increase was limited to girls who also reported other forms of mental health difficulties.

Among boys, the pattern was different. The increase in mental health problems was not accompanied by an increase in self-harming behaviour.

“Repeated self-harm and disordered eating have therefore not increased in general, but only among girls who also experience other mental health problems,” says Daiva Daukantaitė, project leader, associate professor of psychology at Lund University and one of the study’s authors.

What do your findings mean for how we understand and treat recurrent self-harm and eating disorders?

“There is an ongoing international scientific debate about how to understand these problems. One concern is if self-harm should be a diagnosis in its own right or if it is an expression of mental ill-health in general. In any case, our study clearly shows that the increase in these problems goes hand in hand with the increase in broader mental health difficulties”, says Daiva Daukantaitė.

About the study and the research project

The study is part of the Self-Esteem and Life Situation (SoL) research project at Lund University led by Daiva Daukantaitė. At two different periods, with 17 years in between, the researchers in this project examined students in two secondary school grades (about 1,000 students each time) from the same Swedish city. The original study was conducted in 2007 and 2008 and repeated in 2024 and 2025. In each period, the students were measured twice, with a one-year interval. 

The design of the project makes it possible to compare adolescents of the same age and from the same geographical area across two different time periods. In both 2007-2008 and 2024-2025, students were asked the same questions about non-suicidal self-injury, disordered eating, and other mental health difficulties. The measures used had been extensively validated in previous research. The response rate was approximately 90 per cent in 2007-2008 and around 80 per cent in 2024-2025.