Received: 6 May 2019
Accepted: 1 November 2019
First Online: 20 November 2019
Ethics approval and consent to participate
: All adolescents, and parents of adolescents under the age of 16, gave written consent to participate in the study. The Young-HUNT study was approved by the Norwegian Data Inspectorate and the Regional Committee for Medical Research Ethics (REK) and was conducted according to the Helsinki Declaration. This current study was approved by REK (2017/662).
: Not applicable.
: The authors declare that they have no competing interests.