Individually tailored internet-based cognitive behavioural therapy for adolescents, young adults and older adults with anxiety

Anxiety disorders share the feature of excessive fear, anxiety and related behavioural disturbances. Fear is defined as the emotional response to a real or a perceived imminent threat and anxiety is the anticipation of a future threat. The anxiety disorders covered in this thesis are panic disorder with or without agoraphobia, social phobia, post-traumatic stress disorder, generalized anxiety disorder and anxiety disorder not otherwise specified. Cognitive behavioural treatment protocols are typically designed to target one specific disorder and falls under the definition of disorder-specific cognitive behavioural therapy. It is however unclear if this is the most optimal approach in regards to the high comorbidity between anxiety disorders and depressive disorders. Internet-based cognitive behavioural therapy has in the past generally been disorder-specific and from above mentioned predicament two alternative treatment approaches emerged, the tailored and the transdiagnostic approach that aims to simultaneously treat both principal and comorbid disorders. Previous trials on internet-based cognitive behavioural therapy have targeted adults in general and relatively few target adolescents, young adults and older adults. The aims of this thesis were to further develop and test the effects of tailored internet-based cognitive behavioural therapy on the basis of age, for adolescents, young adults and older adults. Specifically by developing and testing the effects of individually tailored internet-based cognitive behavioural therapy for adolescents with anxiety and comorbid depressive symptoms and by adapting and testing the effects of individually tailored internet-based cognitive behavioural therapy for young adults and older adults with anxiety and comorbid depressive symptoms. These aims were tested in two pilot effectiveness studies (Paper I and III) and two efficacy randomised controlled trials (Paper II and IV). The results from these four trials showed significant results across all outcome measures with overall moderate to large effect sizes. The tentative conclusion based on these results is that tailoring internet-based cognitive behavioural therapy can be a feasible approach in the treatment of anxiety symptoms and comorbid depressive symptoms for adolescents, young adults and older adults. Despite the positive findings of the studies in this thesis, there is a need for more research examining the acceptability and effectiveness of internet-based cognitive behavioural therapy for adolescents, young adults and older adults with anxiety and depression before implementation on a larger scale.