Relationships between depressive symptoms and panic disorder symptoms during guided internet-delivered cognitive behavior therapy for panic disorder.

The current study explore the relationship between the trajectories of primary panic disorder symptoms and secondary depressive symptoms during guided internet-delivered cognitive behaviour therapy for panic disorder. The patients (N=143) were recruited from an ongoing effectiveness study in secondary mental health outpatient services in Norway. Weekly self-reported primary panic disorder symptoms and secondary depressive symptoms were analysed. primary panic disorder symptoms and secondary depressive symptoms improved significantly during the course of treatment, and at six months follow-up. Parallel process latent growth curve modelling showed that the trajectory of depressive symptoms and trajectory of panic disorder symptoms were significantly related. A supplementary analysis with cross-lagged panel modelling showed that (1) pre-treatment depressive symptoms predicted a positive effect of panic disorder symptoms early in treatment; (2) high early treatment panic disorder symptoms predicted low depressive symptoms at post-treatment. Guided ICBT for panic disorder is effective for both primary panic disorder symptoms and secondary depressive symptoms. Patients with high pre-treatment secondary depressive symptoms may constitute a vulnerable subgroup. A high level of panic disorder symptoms early in treatment seems beneficiary for depressive symptoms outcome. A time-dependent model may be necessary to describe the relationship between PAD symptoms and depressive symptoms during the course of treatment.