The Development of Anxiety Symptoms in Adolescents

__Abstract__ Anxiety symptoms predict the onset of anxiety disorder and depression, and have been associated with lower levels of well-being even before they reach disorder status. Adolescence is a primary period of interest when it comes to anxiety research, since anxiety disorders most commonly have their onset at an early age, and they are the most frequent mental health problem in children and adolescents. The aim of this thesis is to further our knowledge of the development of anxiety symptoms from late childhood into young adulthood. I used data from the TRacking Adolescents’ Individual Lives Survey (TRAILS), a longitudinal cohort study of children and adolescents (N=2,230) from the general population in the Netherlands. Specifically, we investigated risk factors for the development of panic attacks in adolescence, since the incidence of panic attacks increases dramatically during adolescence. We found that a wide spectrum of Internalizing and Externalizing Problems at age 10-12 years was associated with an increased risk of experience of a panic attack in adolescence, but only Social Problems had a unique association with onset of panic attacks. Furthermore, we examined the relation between pubertal timing (the timing of pubertal development in relation to peers) and anxiety symptoms. We found that in boys, the relation between pubertal timing and anxiety symptoms was age-dependent, while in girls, pubertal timing was not associated with anxiety symptoms. Lastly, we also studied anxiety symptoms in relation to sleep problems. We found that sleep problems and anxiety symptoms hold a direct bidirectional longitudinal association in early adolescence, while later in adolescence, anxiety symptoms still predicted sleep problems, but sleep problems no longer significantly predicted anxiety symptoms. Additionally, we found that the association between anxiety symptoms at age 10-12 and sleep problems at age 12-15 was moderated by parasympathetic reactivity. Two main conclusions of this thesis are (1) that even mild anxiety symptoms are associated with other health predictors and outcomes and (2) that we oversimplify reality if we disregard the possibility of dynamic relations of predictors and outcomes with anxiety symptoms during adolescence