Psychometric properties of the 7-item Generalized Anxiety Disorder Scale (GAD-7) in a large representative sample of Finnish adolescents

•The psychometric properties of the GAD-7 in adolescents have not been known.•The GAD-7 is a reliable and valid self-report measure for generalized anxiety symptoms in adolescents.•The psychometric properties of the GAD-7 are similar to those reported among adults.•Internal consistency of the GAD-7 is good and construct validity may be supported.•The GAD-7 showed to have a unidimensional factor structure in adolescents. Symptoms of generalized anxiety disorder (GAD) are common among adolescents and can lead to severe psychosocial impairment, yet there is a lack of a good quality scale to measure symptoms of generalized anxiety in young people. The 7-item Generalized Anxiety Disorder Scale (GAD-7) is a self-report scale used to measure GAD symptoms and has been validated in adult populations, but the measure's psychometric properties regarding adolescents are unknown. The aim of this study was to investigate the reliability, factorial validity, and construct validity of the GAD-7 in adolescents in a nationally representative sample from a general population. Our study was based on Finnish survey data on 111,171 adolescents aged 14–18 years. Our results show that the GAD-7 demonstrates good psychometric properties in adolescents. The internal consistency of the GAD-7 was good (Cronbach's α = 0.91) and the instrument's unidimensional factor structure was supported. The associations of GAD-7 sum scores with self-report measures of depression and social anxiety supported construct validity. The psychometric properties of the GAD-7 in this sample of adolescents were similar to those reported among adults. However, studies in which diagnostic interviews are performed are needed to demonstrate the diagnostic efficacy of the measure in this age group.