Reflecting on rumination: Consequences, causes, mechanisms and treatment of rumination.

We review research showing that rumination has multiple negative consequences: (a) exacerbating psychopathology by magnifying and prolonging negative mood states, interfering with problem-solving and instrumental behaviour and reducing sensitivity to changing contingencies; (b) acting as a transdiagnostic mental health vulnerability impacting anxiety, depression, psychosis, insomnia, and impulsive behaviours; (c) interfering with therapy and limiting the efficacy of psychological interventions; (d) exacerbating and maintaining physiological stress responses. The mechanisms underlying rumination are examined, and a model (H-EX-A-GO-N - Habit development, EXecutive control, Abstract processing, GOal discrepancies, Negative bias) is proposed to account for the onset and maintenance of rumination. H-EX-A-GO-N outlines how rumination results from dwelling on problematic goals developing into a learnt habit that involves the tendency to process negative information in an abstract way, particularly in the context of poor executive control and negative information-processing biases. These proximal factors integrate experimental evidence to provide a partial answer to the critical question of what maintains rumination. They constitute a pathway by which more distal biological and environmental factors increase the likelihood of rumination developing. Treatments for rumination are reviewed, with preliminary trials suggesting that psychological interventions designed to specifically target these mechanisms may be effective at reducing rumination.