A Specific Case of Non-Specificity: Longitudinal Effects of Dysfunctional Attitudes on Depressive, Eating Disorder and Aggressive Symptoms in Children and Adolescents

An important step in the validation of disorder-specific etiological models is the examination of the predictive specificity of proposed vulnerability factors. It may advance the understanding of the emergence of comorbidity and the identification of at risk-populations for mental disorders. To enhance the currently limited evidence on the specificity of Beck ́s cognitive diathesis—stress model of depression, the present study investigated longitudinal effects of dysfunctional attitudes and stressful life events on the development of depressive, eating disorder and aggressive symptoms in children and adolescents. A large sample of initially asymptomatic children and adolescents completed self-report symptom measures at study entrance and again approx. 20 months later, and reported stressful life events during the study interval. Stressful life events proved to be a risk factor to all investigated symptom domains. Dysfunctional attitudes at T1 were prospectively related to depressive symptoms, aggressive behavior and weight concerns at T2. However, types of associations varied as dysfunctional attitudes showed linear associations with weight concern, but nonlinear effects on depressive and aggressive symptomatology. Findings of the current study thus suggest that dysfunctional attitudes are not uniquely related to the development of depressive symptomatology in children and adolescents, but may contribute to adverse outcomes in various symptom domains. Thus, intervention efforts based on Beck ́s vulnerability – stress model of depression may turn out to be useful in reducing vulnerability to a variety of outcomes in children and adolescents. DOI : 10.14302/issn.2476-1710.JDT-16-1324 Corresponding author: Susanne Meiser, University of Potsdam, Department of Psychology, Clinical Psychology | GRK 1668, KarlLiebknecht-Straße 24-25, 14476 Potsdam, Germany. Email: smeiser@uni-potsdam.de


Introduction
Beck´s prominent cognitive vulnerability -stress model posits that dysfunctional attitudes such as "My value as a person depends greatly on what others think of me" or "If I fail at work, then I am a failure as a person" increase risk for depression following the experience of stressful life events (1,2). Empirical support for Beck´s model has been obtained in child and adolescent samples (3,4). However, little is known regarding the specificity of the observed effects of dysfunctional attitudes to depression. Establishing the predictive specificity of a putative vulnerability factor is yet crucial for the validation of etiological models, particularly when investigating disorders with very high rates of comorbidity, such as depression (5,6). While some studies have examined effects of dysfunctional attitudes with regard to anxiety disorders (6,7), other symptom domains which are also highly comorbid with depression have received little attention. The current study seeks to address this shortcoming by examining associations between dysfunctional attitudes, depressive symptoms, eating disorders and externalizing problems.
Shared risk factors for depression and eating disorders have been reported (8). Preliminary evidence from cross-sectional studies using adult samples suggest that eating disorders may also be associated with elevated levels of dysfunctional attitudes (9,10), but it remains unclear whether the obtained effects may be attributable to comorbid depressive symptoms (11).
Moreover, evidence from younger samples and from longitudinal studies is still missing.
When examining the specificity of a vulnerability factor, it is also important to look at forms of psychopathology which are supposedly unrelated to the vulnerability in question (12). Aggressive behavior, for example, represents such a symptom domain. However, the only findings regarding this domain available to date are those by Hankin and colleagues (7), who did not find associations between dysfunctional attitudes and externalizing symptoms.

The Current Study
At present, evidence for Beck´s vulnerabilitystress model is somewhat inconclusive in children and adolescents, which might in part be due to certain methodological aspects. First, some studies implied nonlinear effects of dysfunctional attitudes on depression indicating weak associations in the lower range, but considerably stronger effects at higher levels of dysfunctional attitudes (3,13). Second, as Dykman and Johll (14) pointed out, effects of dysfunctional attitudes should be investigated in initially asymptomatic samples as Beck´s model was conceptualized to explain how initially asymptomatic but vulnerable individuals become depressed after experiencing stress.
The current study aims to enhance evidence on the specificity of Beck´s vulnerability -stress model to depression by investigating longitudinal effects of dysfunctional attitudes on depressive, eating disorder and aggressive symptomatology during late childhood and adolescence, a particularly crucial period for the initial development of mental disorders. To address potential sources of inconsistent findings in past research, linear and nonlinear methods will be employed using an initially asymptomatic sample, and co-occurring symptoms will be included as covariates in all statistical analyses. In line with existing research, we hypothesize dysfunctional attitudes to show vulnerability effects on future depressive and eating disorder symptoms, but not on aggressive behavior.

Depressive Symptoms
The Depression Test for Children, a German self -report depression inventory (18) designed for screening purposes was used to assess depressive symptoms in children and adolescents ("Depressionstest für Kinder [DTK]"). We used the two subscales "dysphoria/selfesteem" (25 items) and "tiredness/psychosomatic complaints" (14 items). The items are answered in a yes/no format and added up to a sum score representing the total number of reported depressive symptoms. The DTK has demonstrated good validity and reliability (18,19) and has successfully been employed in depression research in child and adolescent samples (20,21). It reached a Cronbach´s α = .84 at T1 and α = .85 at T2 in the current study.

Disordered Eating Behavior
The German version of the child Eating Disorder Examination Questionnaire (chEDE-Q) was employed to assess eating disorder symptoms (22). The chEDE-Q is a widely-used measure of eating disorder symptoms in children and adolescents and has shown good reliability and validity. Participants are asked to rate their behavior during the past four weeks on 22 items capturing symptoms on the four subscales restrained eating, eating concern, shape concern, and weight concern.
Items are to be answered on a 7-point Likert scale.

Stressful Life Events
Stressful life events were assessed via a semistructured interview which was modelled after the Munich Event List (27), a widely used instrument assessing stressful life events via a combination of selfreport checklists and face-to-face interview (28,29

Prediction of Depressive Symptoms
Results of the linear regression analysis of depressive symptoms are presented in Step 2 revealed a significant main effect of life events and a marginally significant main effect of dysfunctional attitudes. The interaction between life events and dysfunctional attitudes was marginally significant in Step 3. Moreover, nonlinear regression revealed a significant cubic effect of dysfunctional attitudes, which is depicted in Figure 1.

Prediction of Eating Disorder Symptoms
Results of the regression model predicting eating disorder symptoms at T2 are presented in Table   3. Eating disorder symptoms at T2 were, in Step  In order to determine whether the marginally significant interaction of dysfunctional attitudes and life events detected in Step 3 was accounted for by a specific symptom type, the linear regression models were re-run separately for the four chEDE-Q subscales restrained eating, eating concerns, shape concerns and weight concerns. These analyses revealed that the interaction of dysfunctional attitudes and stressful life events significantly predicted weight concerns (β = .068, t = 2.220, p = .027, see Figure 2) and marginally significantly predicted eating concerns (β = .060, t = 1.885, p = .060), while for restrained eating and shape concerns, no direct or indirect effects of dysfunctional attitudes were detected (all ps > .190).

Prediction of Aggressive Behavior
As depicted in

Discussion
The aim of the current study was to extend knowledge on the specificity of Beck´s vulnerabilitystress model of depression by exploring effects of dysfunctional attitudes on the development of    dicting change in weight concern. Note that entering T1 weight concern symptoms prior to other predictors into the regression model leaves residual change in symptoms to be explained by subsequent predictors (e.g. dysfunctional attitudes and stressful life events). Note. DAS 2 = squared value of dysfunctional attitudes score; DAS 3 = cubic value of dysfunctional attitudes score.    (39), which share a common liability, represented by a General Psychopathology dimension (the "p-factor") (40). As dysfunctional attitudes and life events showed relations to all investigated symptom domains, the current findings might reflect a general association between these variables and the p-factor.

Predictor
Clearly, future research would benefit from linking investigations of specificity of vulnerability factors to structural models of psychopathology. For example, the inverted-U-shape association between dysfunctional attitudes and aggressive behavior found in the current study might be reflective of a positive association between dysfunctional attitudes and the p-factor, but of a negative one with the externalizing factor once p is controlled for.

Strengths and Limitations
Strengths