Getting stuck in depression: The roles of rumination and emotional inertia

Abstract

Like many other mental disorders, depression is characterised by psychological inflexibility. Two instances of such inflexibility are rumination: repetitive cognitions focusing on the causes and consequences of depressive symptoms; and emotional inertia: the tendency for affective states to be resistant to change. In two studies, we tested the predictions that: (1) rumination and emotional inertia are related; and (2) both independently contribute to depressive symptoms. We examined emotional inertia of subjective affective experiences in daily life among a sample of non-clinical undergraduates (Study 1), and of affective behaviours during a family interaction task in a sample of clinically depressed and non-depressed adolescents (Study 2), and related it to self-reported rumination and depression severity. In both studies, rumination (particularly the brooding facet) and emotional inertia (particularly of sad/dysphoric affect) were positively associated, and both independently predicted depression severity. These findings demonstrate the importance of studying both cognitive and affective inflexibility in depression.

Keywords:

• Rumination
• Emotional inertia
• Depression
• Psychological flexibility
• Perseveration

Acknowledgments

The first author is a Doctoral Research Fellow with the Fund for Scientific Research-Flanders (FWO). This research was supported by University of Leuven Research Council Grants OT/11/031 and GOA/05/04, and by a grant from the FWO.

Notes

¹Following Nezlek (2012), within- and between-person reliability estimates for the negative affect scale were obtained from three-level models with items at Level 1, nested within beeps at Level 2, nested within persons at Level 3.

²To control for possible time-of-day effects, we repeated the multilevel analyses including linear and quadratic effects of time (at Level 1) and their interactions with rumination, brooding and reflection scores (at Level 2). All findings replicated, indicating that the reported associations between emotional inertia and rumination/brooding were independent of time-of-day effects. Additionally, to control for the unequal spacing between successive observations, we repeated the multilevel analyses with the time interval between beeps as a covariate (at Level 1), and replicated all the reported findings.

³All findings replicated using a lag of 10 seconds to calculate affect autocorrelations.

⁴To control for possible time trends, we repeated the multilevel analyses controlling for linear and quadratic effects of time (at Level 1) and their interactions with rumination, brooding and reflection scores (at Level 3). All results replicated, indicating that the reported associations between emotional inertia and rumination/brooding were independent of simple linear or quadratic changes in affective behaviour. We also conducted all multilevel analyses separately for depressed and non-depressed participants. These analyses revealed that neither overall rumination nor brooding or reflection were significantly associated with emotional inertia in either group. Given that depression is known to be strongly associated with both rumination (Nolen-Hoeksema et al., 2008) and emotional inertia (Kuppens, Allen, & Sheeber, 2010), there may not have been sufficient variability in rumination or inertia within each group to detect a relationship between them.

⁵For comparability with Study 1, we report analyses predicting CES-D scores from rumination and emotional inertia. However, we also conducted additional binary logistic regression analyses predicting participants’ MDD group status (0=Non-depressed, 1=Depressed) from rumination and emotional inertia, yielding highly similar results to those predicting CES-D scores, with the exception that dysphoria inertia no longer significantly predicted depressive status when controlling for rumination. Furthermore, when we regressed CES-D scores onto rumination and emotional inertia separately for depressed and non-depressed adolescents, we obtained similar results to those for the whole sample, with the exception that brooding scores did not significantly predict depression severity among clinically depressed adolescents when controlling for emotional inertia levels.