The more, the merrier? Establishing a dose-response relationship for the effects of cognitive control training on depressive symptomatology

Cognitive impairments are frequently observed after remission from depression. There is evidence to show that Cognitive Control Training (CCT) can reduce such impairments and related risk for recurrent episodes. However, it is currently unclear how many CCT sessions are required for short and long-term effects. This randomized controlled trial (RCT) investigates the dose-response relationship of CCT in a sample of individuals with remitted depression (RMD; n=216). Participants were randomly assigned to one of six arms, each receiving a different amount of training sessions (0, 1, 5, 10, 15 or 20 sessions). We found task-specific, but no near cognitive transfer. Mixed-effects models showed that a minimum of 10 training sessions was required for a significant decrease in depressive symptoms shortly after training, but this was not maintained at three- or six-month follow-up. We observed reductions in perseverative thinking in all groups receiving 10 or more CCT sessions, which remained present until six-month follow-up.