Feasibility Randomized Controlled Trial Using a 'Leapfrog' Design

Feasibility Randomized Controlled Trial Using a 'Leapfrog' Design: Optimizing an Internet-delivered Cognitive Training Intervention to Reduce Anhedonia

This study is a small-scale randomized controlled trial (RCT) using a 'Leapfrog' design (Blackwell, Woud, Margraf, & Schönbrodt, 2019) with the aim of investigating feasibility of this design in the context of an RCT of an internet-delivered intervention. The leapfrog design will be applied to a simple cognitive training intervention, imagery cognitive bias modification (imagery CBM), completed over a four-week training period. The trial will start with the three arms described in the initial registration, but these will be removed and new arms added over the course of the trial on the basis of sequential Bayesian analyses.

Inclusion Criteria:

• Aged 18 or over
• Fluent German
• Willing and able to complete all study procedures (including having a suitable device/ internet access)
• Interested in monitoring their mood over the study time-period (one month)
• Score of ≥ 6 on the Quick Inventory of Depressive Symptomatology, including ≥ 1 on item 13 (General Interest), indicating at least mild levels of depression symptoms and anhedonia

Exclusion Criteria:

• No exclusion criteria set