Always look on the bright side of life?: The quest for an online cognitive training to prevent adolescent anxiety and depression

The aim of this thesis was to investigate whether online cognitive training could increase emotional resilience and reduce anxiety and depression in adolescents. Given the peak prevalence of anxiety and depression in adolescence, and the considerable amount of adolescents not using or profiting from existing treatment options, the search for effective preventive or early interventions continues. Based on cognitive models of anxiety and depression, cognitive training paradigms have been developed directly targeting negative biases in information processing and deficits in cognitive control. In the current research, one pilot study (chapter 3) and three large scale randomized controlled trials were performed to investigate the effects of online training targeting attentional bias, interpretation bias and working memory in adolescents. Various training paradigms were tested in both unselected adolescents (universal prevention; chapters 2, 4, 5, & 6) and selected adolescents with heightened symptoms of anxiety or depression (indicated prevention; chapters 7 & 8). In general, results showed that two training paradigms were effective in changing attentional and interpretation bias as assessed with tasks that were closely matched to the training tasks. However, hardly any training effects were observed on emotional outcome measures. That is, anxiety and depressive symptoms reduced and emotional resilience improved to the same extent in both training and placebo or no training control groups, both at the short term and at six to twelve months follow-up. Future research should focus on improving training paradigms and assessment tasks, both in terms of targeting the relevant cognitive processes and increasing adolescent engagement