Exposure Treatment in Anxiety Disorders: Proof of Principle for an a Priori Response Prediction Approach

While knowledge on the neurobiological signatures of fear and anxiety disorders and, in particular, their association with treatment outcome is accumulating, clinical translation still awaits empirical proof of evidence. Exposure-based cognitive-behavioral therapy (CBT) is a first-line treatment, but clinically significant change is only seen in approx. 50-65% of patients. Patient stratification is a powerful option to increase treatment response; however, developing prognostic markers suitable for single-patient predictions still is in its infancy and crucially requires external cross-validation embedded within an a priori prediction approach - a procedure yet largely missing in the field of biomarker research. Employing a bicentric strategy the aim of this study is to test the hypothesis that a priori prediction of treatment outcome based on neurobiological measures is possible in a second, independent sample. Building upon findings from previous mechanistic studies, These will be incorporated into the development of a predictive pattern comprising fear-relevant genotypes and molecules targeting neuropeptides, related epigenetic signatures as well as neurofunctional activation patterns associated with fear circuitry functions, and clinical data. Pre-treatment neurobiological signatures will be tested for their potential as a predictive response marker towards behavioral exposure (virtual reality exposure treatment (VRET) and an in vivo behavioral avoidance test) in a model disorder of fear circuitry dysfunctions (spider phobia). Multivariate pattern analyses employing a machine learning framework will be used to generate predictions on the individual patient level and to cross-validate markers in a second, independent sample. While at site A predictions will be generated following completion of the treatment, response will be predicted at site B a priori, but in a double-blind manner. Comparison of observed vs. predicted response rates will serve as a test of hypothesis. In addition, neuroplastic (on a subsample) and epigenetic changes induced by VRET treatment will be assessed following treatment and, in case of epigenetics, also after 6-months follow-up.