The Trajectory of the Co-Occurrence of Anxiety and Depressive Symptoms in Treatments for Generalized Anxiety Disorder

Research has shown anxiety and depression to be highly comorbid (Kessler et al., 2005). Such comorbidity is particularly prevalent in Generalized Anxiety Disorder (GAD), with comorbidity rates ranging from 45% to 98% (Goisman, Goldenberg, Vasile, & Keller, 1995). Despite the commonalities and the frequent co-occurrence of GAD and depression, little is known about the interactive process of symptom changes in GAD and depression during therapy. This study explored the relationship between the trajectories of generalized anxiety and depressive symptoms over the course of an Acceptance Based Behavioral Therapy (ABBT) and Applied Relaxation (AR). Across treatment, participants reported significant improvements in both symptom clusters. Latent growth curve analysis showed that more rapid changes in anxiety symptoms occurred in the first half of treatment than the last half and depressive symptom scores followed a largely linear trajectory and then leveled off. Additionally, the trajectories of anxiety and depressive symptoms were correlated suggesting that change over time in one symptom cluster is associated with change in the other. Both of these trajectories were predictive of treatment response. These results demonstrate that not only do non-linear symptom trajectories occur, but also that the presence of co-occurring symptom clusters does not diminish the efficacy of treatment