Cognitive behavioral therapy (CBT) is a well-documented and effective method for the treatment of children and adolescents with anxiety disorders. Lately there has been an increase in the development and use of internet-based CBT programs (ICBT), as a means to reduce costs and enhance accessibility of psychological interventions. ICBT has proven efficacious towards adults with anxiety disorders. Research in the field of ICBT with children and adolescents is still in its infancy though and to date, no program targeting anxiety disorders has been developed nor evaluated in Denmark. The primary objective of this study is to investigate the efficacy of a newly developed internet-based treatment program for adolescents with anxiety disorders. The effect will be examined in a randomized controlled trial comparing ICBT to a wait-list control condition.

Within the context of a research and teaching clinic at the Department of Psychology and Behavioral Sciences, Aarhus University, Denmark, 70 adolescents aged 13-17 with a primary anxiety disorder as assessed by the ADIS C/P will be randomly allocated to either a 3 month wait-list control condition or a treatment condition.

The treatment consists of an internet-based self-help program for adolescents with anxiety disorders called 'Chilled Out', based on material from the well-established manualised group-treatment Cool Kids Program: Adolescent version. It consists of 8 CBT-inspired modules of approximately 30 minutes each distributed over a 14-week period. The program is interactive using a combination of different media (text, audio, illustrations, cartoons, and videos) to deliver psychoeducation and CBT-inspired techniques, activities and exercises for adolescents to manage their anxiety. In addition, the adolescent will receive a limited amount of therapist support calls.

Participants (youth and parents) are assessed with semi-structured diagnostic interviews and self-report measures before treatment, after 14 weeks (post treatment) and 3 months after treatment (follow-up).

Participants are assessed at pre, post and 3-month follow up.

Inclusion Criteria:

• a primary diagnosis of separation anxiety disorder, generalized anxiety disorder, social phobia, specific phobia, obsessive compulsive disorder or panic disorder
• age between 13 and 17 years
• ability to read and write in Danish
• direct access to a home computer and internet

Exclusion Criteria:

• high degree of comorbid depression (CSR above 5 as measured with ADIS-IV)
• substance abuse
• current self-harm or suicidal ideation
• pervasive developmental disorder
• learning disorder
• intellectual disability
• psychotic symptoms

All participants are asked not to make changes to their medication status during the course of the trial