There's been a lot of coverage in the media around the world about the mental health difficulties facing boys, but looking at figures for mental health problems in children and teens, there's clearly something going on with girls too. For some years, research has shown more girls are experiencing problems than boys, with a troubling spike in difficulties showing up in the late teens. On today's programme, Claudia Hammond explores the issue with a variety of guests. She visits King's College London's (KCL) Institute of Psychiatry, Psychology and Neuroscience to speak to Gemma Knowles, a lecturer in epidemiology and youth mental health; Craig Morgan, professor of social epidemiology and co-director of ESRC Centre for Society and Mental Health; and Valeria Mondelli, a clinical professor of psychoneuroimmunology - about their work with young people, trying to uncover the deeper causes and to find new solutions. She also hears from some of the young people involved in a major study into mental health, conducted by the team at KCL and spanning nearly a decade. Claudia is joined by Dr Linda Blair, a clinical psychologist, who uses her own professional experiences to discuss the trends and challenges of youth mental health. Presenter: Claudia Hammond Producer: Dan Welsh