Why ruminators won't stop: the structural and resting state correlates of rumination and its relation to depression.

BACKGROUND Rumination is a good predictor of major depression. The current study explores the structural and functional neural correlates of rumination. METHODS To explore structural correlates of rumination (RRS, Treynor et al., 2003) we used voxel-based morphometry. We relate these correlates of rumination to concurrence of grey matter reductions in depressed patients by means of a quantitative meta-analysis on 16 VBM studies. Resting state data was used to compute maps of the amplitude of low frequency fluctuations. RESULTS Rumination correlated negatively with grey matter volume in bilateral inferior frontal gyrus (IFG), left anterior cingulate cortex (ACC), and bilateral mid cingulate cortex. The volume reductions were within proximity of grey matter reductions identified in the meta-analysis on depressed patients in bilateral IFG and ACC. Moreover reductions in resting state activity were overlapping with volume reductions correlated with rumination in ACC and right IFG. LIMITATIONS The participants were all healthy control subjects. Future research is needed to explore the neural correlates of rumination in major depression. CONCLUSIONS The results show that rumination is associated with volume and resting state reductions in brain areas that have been related to cognitive control process of inhibition and thought suppression. We conclude that rumination not only qualifies as a behavioural predictor of major depression but also goes along with neuroanatomical abnormalities that are similar to those identified for depression.