Understanding depressive rumination from a cognitive science perspective: The impaired disengagement hypothesis

Abstract

Persisting negative thoughts are considered a hallmark of depression. Recent information-processing approaches have begun to uncover underlying mechanisms of depressive rumination. Despite marked advances in this area, there is a lack of integration between psychopathology and cognitive (neuro) science research. We propose the ‘impaired disengagement’ hypothesis as a unifying framework between both approaches. The core tenet of our model is that prolonged processing of self-referent material is due to impaired attentional disengagement from negative self-referent information. We discuss empirical evidence for this framework and outline future ways in which the causal predictions of this model can be tested. The proposed framework can account for effectiveness of various treatments for depression and may aid in devising new interventions to target depressive cognition.

Introduction

Persistent negative cognition is a hallmark of depression and anxiety that is assumed to play an important role in the etiology and maintenance of affective disorders (Clark et al., 1999, Watkins, 2008). Although engaging in prolonged and repetitive thinking about one's self in relation to the social environment, which could increase upon the encounter of stressful events or emotional states, is in essence a constructive and normative process, this process can become exaggerated and associated with detrimental effects in several forms of psychopathology (Watkins, 2008). In this article we focus on an important form of depressive cognition, rumination, and we propose a new theory based on information-processing and affective neuroscience research to account for heightened levels of rumination observed in depression. This new theory holds important implications with regard to strategies that can directly target the mechanisms underlying rumination.

It is important to mention that, at the outset, we clearly distinguish between cognitive processes and products, as proposed by Ingram, Miranda, and Segal (1998). Attentional control, as measured by experimental tasks, is considered a process influencing rumination as measured by questionnaires. Although definitions of rumination (as will be discussed in the later part) sometimes refer to rumination as “a process” of thinking, we regard rumination as a certain style of self-referential thinking. The negative cognitions associated with a ruminative thinking style are seen as cognitive products.

Cognitive theories have emphasized the role of negative cognitions in the etiology and maintenance of depression. According to Beck's influential cognitive theory (Beck, Rush, Shaw, & Emery, 1979), depression is characterized by presence of negative schemas, defined as mental representations of past experiences, containing dysfunctional attitudes about the self (Beck, 1967, Beck, 1995). These underlying schemas have an important influence on the way information is processed, guiding one's interpretation, attention and memory for personally relevant negative experiences (Clark et al., 1999). Activation of the schemas in confrontation with stressful life events and negative mood states leads to specific negative automatic thoughts including negative cognitions about the self, the world and the future (the so called negative cognitive triad, Beck, 1995). Negative cognitions, in turn, further maintain and exacerbate negative affect, leading to a vicious cognitive–affective circle with enhanced depressive symptoms (Teasdale, 1988, Watkins, 2008).

Although the negative content of depressive cognition is proposed to play an important role in the vulnerability for depression (Alloy et al., 2000, Clark et al., 1999), recent theoretical models highlight the importance of underlying cognitive processes that might be responsible for elevated and persistent negative cognition and affect (Joormann, Yoon, & Zetsche, 2007). Research has demonstrated that activation of negative cognitions or representations in working memory may not necessarily result in increased and prolonged negative affect. Instead, it is the ability to regulate negative affect that plays an instrumental role in determining which individuals are at risk to experience prolonged negative affect upon encounter of stress (Joormann et al., 2007). Regulation of negative mood however seems to be dependent upon the efficient exercise of working memory functions involved in the regulation of negative information. In a related manner, individual differences in the cognitive control functions are proposed to be related to a ruminative thinking style (Davis & Nolen-Hoeksema, 2000).

In recent years, rumination has been defined as “behaviors and thoughts that focus one's attention on one's depressive symptoms and on the implications of those symptoms” (Nolen-Hoeksema, 1991, p. 569). The response style theory of depression (Nolen-Hoeksema, 1991) proposes that individuals differ in their reaction to negative mood states and that rumination is a trait-like response style to distress. Individuals are engaged in depressive rumination because they believe that ruminating about their mood and symptoms will help to understand themselves better. However, rather than leading to increased self-understanding, depressive rumination augments sad mood and negative thinking by focusing attention on current mood (Lyubomirsky & Nolen-Hoeksema, 1995). Later, it was proposed that the harmful effects of rumination stem not from attention to distress per se, but from self-focused attention that is negative, evaluative and judgmental (Rude, Maestas, & Neff, 2007).

To assess individual differences in the tendency to ruminate, Nolen-Hoeksema and Morrow (1991) developed the Ruminative Response Scale (RRS). This scale has high internal consistency and acceptable convergent validity (Butler & Nolen-Hoeksema, 1994, Nolen-Hoeksema & Morrow, 1991). Various versions of this 22-item scale have been used in numerous studies over the years. Factor analyses of the RRS have identified two distinct subtypes of rumination (Treynor, Gonzalez, & Nolen-Hoeksema, 2003). The first, reflective pondering, is a more adaptive form of rumination and reflects the degree to which individuals engage in cognitive problem solving to improve their mood. The second, depressive brooding, is a more maladaptive form of rumination and reflects the degree to which individuals passively focus on symptoms of distress and the meaning of those symptoms. Both rumination scales involve focusing on distress, but the brooding scale contains more self-critical, evaluative, and judgmental statements (Rude et al., 2007). Depression is specifically characterized by high levels of brooding (Burwell & Shirk, 2007, Joormann et al., 2006, Treynor et al., 2003).

Rumination in response to negative mood increases vulnerability to depression. Experimental studies testing the effects of rumination have generally used the rumination induction procedure developed by Nolen-Hoeksema and Morrow (1993). This procedure increases ruminative thinking and has been shown to heighten and prolong negative mood and cognition in dysphorics (Morrow & Nolen-Hoeksema, 1990, Nolen-Hoeksema & Morrow, 1993) and in clinically depressed participants (Donaldson & Lam, 2004, Lavender & Watkins, 2004, Watkins & Moulds, 2005, Watkins & Teasdale, 2001). Induction of rumination also hampers problem solving and task performance (Watkins & Brown, 2002). In addition, numerous studies have demonstrated that rumination is associated concurrently with depressive symptoms (Treynor et al., 2003) and prospectively with the onset (Nolen-Hoeksema, 2000), severity (Just & Alloy, 1997, Nolen-Hoeksema & Morrow, 1991) and duration (Nolen-Hoeksema, 2000, Nolen-Hoeksema et al., 1993) of depression, and recovery from depression (Kuehner & Weber, 1999, Schmaling et al., 2002).