تغییرات صریح و ضمنی اعتماد به نفس اندازه گیری شده در درمان اختلال افسردگی اساسی: شواهد برای جبران اعتماد به نفس تلویحی

Background and objectives Self-esteem has been claimed to be an important factor in the development and maintenance of depression. Whereas explicit self-esteem is usually reduced in depressed individuals, studies on implicitly measured self-esteem in depression exhibit a more heterogeneous pattern of results, and the role of implicit self-esteem in depression is still ambiguous. Previous research on implicit self-esteem compensation (ISEC) revealed that implicit self-esteem can mirror processes of self-esteem compensation under conditions that threaten self-esteem. We assume that depressed individuals experience a permanent threat to their selves resulting in enduring processes of ISEC. We hypothesize that ISEC as measured by implicit self-esteem will decrease when individuals recover from depression. Methods 45 patients with major depression received an integrative in-patient treatment in the Psychosomatic University Hospital Bonn, Germany. Depression was measured by the depression score of the Hospital Anxiety and Depression Scale (HADS-D). Self-esteem was assessed explicitly using the Rosenberg Self-Esteem Scale (RSES) and implicitly by the Implicit Association Test (IAT) and the Name Letter Test (NLT). Results As expected for a successful treatment of depression, depression scores declined during the eight weeks of treatment and explicit self-esteem rose. In line with our hypothesis, both measures of implicit self-esteem decreased, indicating reduced processes of ISEC. Limitations It still remains unclear, under which conditions there is an overlap of measures of implicit and explicit self-esteem. Conclusions The results lend support to the concept of ISEC and demonstrate the relevance of implicit self-esteem and self-esteem compensation for the understanding of depression.

Major depressive disorder is known to be the most prevalent mental disorder. About 5% of the population suffer from depression [1], while approximately one fifth develop one or more episodes of major depression in their life [2]. Self-esteem has been claimed to be an important factor in the development and maintenance of depression [3]. Studies show self-esteem scores to be reduced in depressed individuals [4] and [5]. The majority of these studies employ self-report questionnaires to measure self-esteem. However, although widely used, self-report data have longtime been criticized for at least two reasons: First, participants have to be motivated to disclose their genuine attitudes, e.g., individuals may give biased answers due to reasons of social desirability. Second, they must also be able to access the construct that they are asked about, e.g., some may misattribute emotions and thus cannot answer questions aiming at the reasons of their emotions correctly. The implicit measurement of an attitude aims at overcoming these limitations by the following principles: (1) the participant's awareness of the fact that this specific attitude is measured may be reduced, (2) the participant may not have conscious access to the attitude in focus, and (3) the participant's control over the outcome of the measurement may be limited [6]. Thus, “implicit measures might be less biased by deliberate attempts to conceal the attitude and that they might even reflect attitudes of which the respondent is not aware” (p. 401) [7]. Although measures of implicit self-esteem were repeatedly criticized to have only low to modest reliability and insufficient convergent validity [8] and [9], several studies obtained results indicating that implicit self-esteem comprises information that goes beyond the information provided by explicit measures of self-esteem [10] and [11]. Bosson et al. [8] concluded that among measures of implicit self-esteem, reliability was best for the Implicit Association Test (IAT) [12] and the Name-Letter Test (NLT) [13] and [14]. Subsequently, the majority of empirical research relies on these measures [9] (see method section for a detailed description of both measures). Dual process accounts to cognitive vulnerability to depression [15] and [16] suggest that two processing systems determine how an event is interpreted. The automatic or implicit system operates by automatically activating memory concepts in an effortless and unintentional manner and without charging cognitive resources. The deliberate or explicit system is characterized by effortful, intentional resource consuming processing. Haeffel et al. [16] assume that life events first trigger a rapid, automatic, and unintentional response that may activate negative self-schemas. In a second step this interpretation may be reinterpreted by explicit processes. Whereas some researchers presume that the main cause of cognitive vulnerability lies within negative implicit self-schemas [17], other investigators assume that explicit cognition can be the source of vulnerability to depression [18]. Haeffel et al. [16] tested the predictions of dual process models and observed in their first study, that only participants with lower implicit self-worth (IAT) experienced immediate emotional distress after a failure feedback. In their second study, using a prospective design, they found that implicit self-worth (IAT) as well as explicit cognitive styles interacted with negative life events in predicting later depression. When entered simultaneously into a regression model, only explicit self-worth interacted significantly. The authors argue that implicit self-worth affects immediate distress, whereas explicit cognitions determine the long-term risk to depression. Also supporting the role of explicit processing, Steinberg et al. [19] found implicit self-esteem as measured by IAT to predict depressiveness only for individuals with depressogenic cognitive style. Taking a closer look at implicit self-esteem in depressed individuals reveals a mixed picture (see DeHart et al. [20] for a more detailed review): De Raedt et al. [21] observed implicit self esteem in currently depressed individuals to be as high as in non-depressed controls using the IAT (study 1) and the NLT (study 2). In study 3 they observed higher implicit self-esteem for depressed compared to non-depressed participants using the Extrinsic Affective Simon Task (EAST, cf. De Houwer [22]). Accounting for suicidal ideation in depressed individuals, Franck et al. [23] find lower implicit self-esteem (IAT) in a depressed sample without suicidal ideation than in a non-depressed group as well as in depressed individuals with suicidal ideation. Implicit self-esteem of depressed with suicidal ideation was as high as in the non-depressed group. Unfortunately, suicidal ideation was not controlled in other studies on implicit self-esteem in depressed samples and as a consequence we do not know to what extent the results are affected by suicidal ideation. Gemar et al. [24] observed higher implicit self esteem (IAT) in formerly depressed than in never depressed and currently depressed participants, but after negative mood was induced, implicit self-esteem of the formerly depressed dropped to the level of the never depressed and the currently depressed. This pattern of results was replicated by Franck et al. [25]. However, Franck et al. [26] observed no differences in implicit self-esteem using the NLT in currently, formerly, and never depressed individuals. Nevertheless, implicit self-esteem predicted future depressive symptomatology. Risch et al. [27] accounted for the number of depressive episodes and observed that implicit self-esteem (IAT) was the same for never depressed and remitted patients with recurrent depressive episodes, which both had higher implicit self-esteem than first-onset depressive patients and currently depressive patients with recurrent depressive episodes. Taken together, the most frequent finding is that currently depressed and non-depressed samples do not differ with respect to implicit self-esteem [21], [25] and [26], although implicit self-esteem has also been found to be reduced [27] or elevated [21] in currently depressed individuals compared to non-depressed. Furthermore, implicit self-esteem can be moderated by suicidal ideation [23] and history of depression in depressed [27] or remitted [27], [24] and [25] patients, but see Franck et al. [26] for contrary results. Moreover, implicit self-esteem in remitted patients is affected by mood induction [24] and [25]. Despite the stable finding of reduced explicit self-esteem in depressed populations, reduced implicit self-esteem seems not reliably associated with clinical depression in cross-sectional studies. A possible explanation for these heterogeneous results may be compensatory responses to self-threatening situations, as will be outlined in the following paragraphs. Based on research demonstrating that implicit self-esteem improves after participants have been confronted with self-threatening situations, several authors proposed that self-defensive processes can be triggered under conditions of threat to the self and that these processes can compensate potential loss in self-esteem [10], [28] and [29]. They argue that measures of implicit self-esteem are particularly sensitive to these compensatory processes. The studies that focused on the consequences of self-threatening situations in healthy individuals used different ways to manipulate self-threat. For example, Jones et al. [29] observed enhanced implicit self-esteem after participants with high explicit self-esteem wrote about an aspect of themselves they wish to change but not when they were asked to write about a positive aspect of themselves or a self-irrelevant topic. Other studies yielded analogous effects on the liking of others with similar names [30] or choosing brands with names resembling their own name [31] after participants had performed a self-threatening writing task. Improved implicit self-esteem was also observed after negative life events [28] and social rejection [10]. Rudman et al. [10] propose an automatic self-esteem defense mechanism called implicit self-esteem compensation (ISEC) that automatically regulates self-esteem whenever the self is seriously threatened. They argue that given the high frequency of threats to the self in everyday life, the idea of a process that buffers self-esteem would be compelling. They propose that ISEC is an automatic self-regulatory mechanism that countervails self-decrementing situations in an effortless manner. This account may explain why implicit self-esteem is not reduced in depressed samples as reviewed above. Based on the findings that healthy individuals employ this mechanism when confronted with ego-threats, it makes sense to assume a similar mechanism in depressed individuals: depressed individuals reveal low explicit self-esteem [4] and [5], adverse self-schemas [32], [33] and [34] and overestimate the frequency of future life events [35]. They are prone to disadvantageous attribution styles [36] as they attribute negative life events internally but positive life events externally (see Sweeney et al. [37] for a meta-analytic review of 104 studies) thereby experiencing more self-threatening events [38], [39] and [40]. Given this daily struggle with threatening events on the one hand, and the results of elevated implicit self-esteem after manipulations of threats to the self [10] and [29] on the other hand, we expect implicit self-esteem compensation to be a most relevant process in depression. ISEC may thus be a reason, why depressed individuals reveal consistently reduced levels of explicit but not implicit self-esteem as reviewed above. The heterogeneous results concerning the relative extent of implicit self-esteem of depressed in comparison to healthy individuals may be a consequence of ISEC protecting the depressed self from adverse threats. Implicit self-esteem compensation may often reach or sometimes even prevail the level of healthy controls. Within the dual process framework ISEC can be understood as a mechanism stabilizing implicit self-esteem. In this conception implicit self-esteem may fluctuate in response to self-threatening events and thus exhibit a state component [28]. In dual process accounts for the vulnerability to depression, implicit self-esteem is often understood as rapid and automatic processing mode that develops over a long period [15] and is based on stable memory constructs [16]. However, there is evidence that implicit self-esteem can be affected by classical conditioning [41], induction of negative mood [24] and [25], daily negative events [28], or after threats to the self [10], [28], [29], [30] and [31]. DeHart and Pelham [28] argue that implicit self-esteem has trait as well as state aspects and propose that implicit self-esteem has a trait level around which the state level can fluctuate. If depressed individuals possess a low level of implicit self-esteem, ISEC may represent such a fluctuation that can elevate implicit self-esteem to a level observed in non-depressed controls. This may explain, for example, why depressed individuals with suicidal ideation, but not without suicidal ideation, revealed higher implicit self-esteem than non-depressed [23]. Self-threat is presumably extremely pronounced in individuals with suicidal ideation and, as a consequence, ISEC may yield particularly high levels of implicit self-esteem. Furthermore ISEC may also explain the frequent finding that implicit self-esteem is generally positive, even in samples with major depression. For example the performance of currently depressed participants in the IAT reveals stronger associations for self-positive and other-negative than for self-negative and other-positive combined trials [21] and [27]. Also the NLT is positive for depressed individuals as they prefer letters from their own name over other letters [21] and [26]. Given the more negative self-schemas that are observed in depressed individuals, one may expect negative scores for these measures of implicit self-esteem. The frequently observed positive implicit self-esteem in depressed samples may also be a consequence of ISEC, because depressed individuals are in particular need of processes that compensate the omnipresent threats to their self. In the present study we examine the role of implicit self-esteem compensation for depressed individuals by focusing on the change of explicit and implicit self-esteem during the course of treatment of inpatients with major depression. Because many studies demonstrated that explicit self-esteem improved as a consequence of the successful therapy of depression [4] and [5] we accordingly expect to replicate this pattern in the present study (hypothesis 1). If, in contrast to explicit self-esteem, implicit self-esteem compensation is protecting the self of depressed individuals against daily threats as suggested above, one would suppose a particularly high implicit self-esteem at the beginning of treatment which, as protective processes decrease during recovery, decreases as patients recover from depression. We thus expect implicit self-esteem to decline during the course of treatment (hypothesis 2).

The findings underline the importance of implicit self-esteem compensation in depressed patients as a relevant implicit mechanism for stabilization that may undergo specific changes during treatment. Within the dual process account for cognitive vulnerability in depression, ISEC can explain previously not well understood findings such as a higher implicit self-esteem in depressed patients. Measures of implicit self-esteem may help to gain more insight into these processes of protecting self-esteem, thereby hopefully paving the way to optimize the treatment of depression.