The role of concreteness in repetitive negative thinking: Temporal dynamics and the predictive value for depression...

Repetitive negative thinking (RNT) is an important transdiagnostic process involved in the development and maintenance of depression. Evidence suggests that maladaptive RNT is characterised by reduced concreteness. However, the temporal relationship between concreteness of RNT and depressive symptoms, as well as changes in concreteness during psychological treatment, remain unclear. Therefore, the current study investigated (a) whether momentary RNT concreteness explains variance in the prediction of momentary depressive symptoms beyond momentary RNT, (b) whether momentary RNT concreteness increases over the course of psychotherapy and (c) the temporal precedence between momentary RNT concreteness and momentary depressive symptoms.

Seventy-seven depressed patients participating in a randomised controlled trial were assessed using Ecological Momentary Assessment (EMA) during a seven-week inpatient psychological treatment. EMA, conducted three times daily, included measures of depression, RNT, and a free-text item assessing patients' RNT thoughts, which were rated for concreteness by trained raters. Weekly depression severity was assessed using the Beck Depression Inventory II. Hypotheses were tested using multilevel modelling.

Concreteness of RNT was significantly associated with depression. A model incorporating both RNT and concreteness accounted for significantly more variance in depression than a model with RNT alone. Concreteness of RNT increased throughout treatment, dependent on patients' improvement in depression severity. Depression levels predicted subsequent concreteness, but not vice versa.

Concrete thinking is consistently related to depression and improves over the course of effective psychological treatment. However, the current findings do not suggest that changes in concreteness predict subsequent reduction of depression levels. Future research should explore long-term temporal dynamics between RNT concreteness and depression to evaluate the potential of concreteness as a mechanism of change in psychological treatments in more detail. The clinical trial is registered at clinicaltrials.gov (NCT03287362).