Placebo responsiveness and cognitive behavior therapy outcomes: Investigating expectations and neural variability in anxious individuals

Internet-delivered cognitive behavior therapy (CBT) for social anxiety disorder is an evidence-based treatment in regular health care. Still, a considerable proportion of treated patients do not respond. There is also a debate on the importance of patients expectations’ for therapeutic outcomes. However, experimental evidence is lacking to answer this question.

Our aim is thus to investigate the placebo response in social anxiety disorder, and the link between initial placebo responsiveness and subsequent outcome of CBT. First, we will manipulate expectations of anxiety relief.

A benzodiazepine (a common anti-anxiety drug) will be administered with correct or incorrect information about clinical efficacy during a public speaking task.

Self-reports and moment-to-moment variability in neural response will be measured with functional magnetic resonance imaging (fMRI) during the manipulation of expectations.

The balanced placebo design allows us to dissect the total treatment effect into its components: drug, placebo, and interactions between the two. Second, patients undergo internet-delivered CBT after completing the placebo experiments.

This project aims to unravel expectations´ influence on treatment response, and has a two-fold significance, 1) the scientific understanding of the neural mechanisms of treatment expectations, central for placebo, and 2) the development of pre-treatment predictors of CBT outcome which could improve precision in clinical decision making.