Trajectories of anxiety symptoms in adolescents: Testing the model of emotional inertia

Two predictions derived from a recently introduced model of psychotherapy outcome were tested, assuming the dynamical relationship between the individual's emotional trajectory and the force of intervention necessary to change this trajectory: (a) only a high intensity treatment would succeed to lower the increasing trajectory of anxiety, and (b) high as well as low intensity treatments would equivalently lower the non-increasing trajectory of anxiety. Methods: Seventy-four adolescents (58.40% girls; M = 14.65 years, SD = 0.53) were randomly assigned to a high intensity treatment condition, a low intensity treatment condition, or a waiting list condition. Results: Only the high intensity treatment reduced the anxiety when participants showed an increasing trajectory (p < .01). None of the treatments reduced anxiety when a previously non-increasing trajectory was shown. Conclusions: These findings support the theoretical predictions and underscore the need to consider not only how severe the anxiety is but also the time course of anxiety in applied treatment settings.