Study: Half of all teenagers treated for severe obesity have neuropsychiatric problems Half of all young people treated for severe obesity have neuropsychiatric problems, according to a new study by researchers from Lund University and Gothenburg, Sweden, among others. Two thirds of the teens suffered from some type of mental health problem, as reported by themselves or their parents. Both obesity and mental illness have increased among young people during the 2000s. Researchers have long observed a connection between obesity and ADHD/depression/eating disorders, but it has seldom been studied. The present study involved 48 teenagers (73% girls), with an average age of 15 and an average BMI of 42, which is severe obesity. Half of the participants received medical treatment for obesity, while the other half underwent surgery.