Research pointing to the importance of cognitive distortions in the etiology and maintenance of depressive feelings has led to the development of cognitive behavioral interventions for youth. These interventions are not only used for the treatment of existing disorders, but also for the prevention of new cases. Recent meta-analyses suggest that preventive interventions can significantly reduce depressive symptoms or risk for future depressive symptoms compared to control groups [1
]. More research is needed to test if depression prevention programs are effective when implemented in community settings under real-world conditions, and to uncover the causal mechanisms and potential mediators of the effects [1
One of the best studied depression prevention programs is the Penn Resiliency Program (PRP) [4
]. PRP is a theory-based universal school-based depression prevention program designed for early adolescents (ages 10-14 years) that teaches cognitive-behavioral and social problem-solving skills. Although PRP is described as not having replicated effects across trials in the meta-analytic review of Stice et al. [3
], positive conclusions about this program are drawn in an evaluation of all of the 17 existing controlled studies evaluating PRP with 2,498 participants in total [1
]. Researchers testing the Penn Resiliency Program often used rigorous experimental designs with extended follow-ups (up to 36 months) showing small but significant and consistent systematic effects on depressive symptoms, especially at 12-month follow-up assessments. Concluding, PRP seems to be a thoroughly studied theory-based program and a good basis for further development of depression prevention. In the Netherlands, no school-based depression prevention program for adolescents exists as of yet and therefore the PRP-program has been translated and rigorously adapted to the Dutch situation in close collaboration with the original developers. The Dutch program is titled "Op Volle Kracht" (OVK) [5
]. The primary aim of the present study is to test the transportability and effectiveness of OVK when it is delivered by school teachers and provided to adolescents with a high risk to develop depressive symptoms (selective prevention).
Selective prevention implies focusing on a population whose risk is deemed to be above average to develop symptoms of a given disorder. This type of prevention has been found to be more effective than universal prevention [6
]. Commonly distinguished groups with high risk for developing depressive symptoms are youth with: elevated depressive symptoms at baseline, a pessimistic explanatory style, parents with mood disorders, family conflicts, or youth who belong to an ethnic minority, live in low income areas and who are more exposed to life stressors [3
]. Youth from families with a low social economic status are exposed to chronic levels of uncontrollable negative life events and to more maternal distress because of greater economic hardship [8
]. Selective prevention is relevant for people in the teenage years [6
], because depression rates begin to rise in early adolescence with a peak in mid-late adolescences [12
]. In the present study, a selective prevention program for depression is targeted at adolescents living in low income areas in the Netherlands.
Since the purpose of the OVK program is to prevent
youth from developing depression symptoms, a structural, easily accessible implementation on a large scale is needed to reach early adolescents who have not developed clinical depressive symptoms yet. This will be achieved by implementing the program in the regular school curriculum. No stigmatization will occur as a result of singling out individuals to receive the program. In addition, we expect the effects of the class-based program to be more easily consolidated because the classmates will interact and learn from each other in day-to-day experiences. For a feasible implementation of the program in the school curriculum, the following pragmatic and logistic arguments and costs have to be taken into account. Because hiring external professionals for providing the program is too expensive for most schools, it is important that school teachers are able to deliver the program. It is therefore pivotal to study if school teachers can provide the program as effectively as clinicians and/or the developers of the program, and to evaluate practical implementation challenges and difficulties. Meta-analyses of the PRP program show significant effect sizes regardless of group leader type [1
], although it appears that effect sizes are higher when the program is delivered by professional interventionists compared to endogenous providers (e.g. teachers) [3
In addition to studying the main effects of this program on symptoms of depression, the mechanisms and possible factors underlying the effects of the program are of great interest. To this end, the mediating effects of two specific concepts will be examined in the current study: distorted cognitions and alexithymia. Distorted cognitions are important determinants of depressive feelings. Three central theories explain the etiology and maintenance of depressive feelings with the role of cognitions: Beck's cognitive theory of depression [13
], the hopelessness theory of depression [14
] and the response styles theory [15
]. According to Beck's theory, stressful events activate maladaptive self-schemata (i.e. a style of cognitive interpretation) which generates specific cognitive errors such as 'overgeneralization' and 'catastrophizing'. The hopelessness theory [14
] states that an attributional style with negative outcome expectancy and expectations of helplessness about changing the likelihood of occurrence of these outcomes are causal for developing a (subtype of) depression. People with a negative attributional style have a tendency to attribute negative events to stable, global and internal factors which leads to hopelessness and consequently to symptoms of depression. Both theories describe a diathesis stress component [16
]; the cognitive styles are only activated if they are accompanied by negative life events. The response styles theory [15
] argues that the severity and duration of the symptoms of depression are determined by three styles in which individuals respond to their symptoms of depression: rumination (excessive thinking about the same topic), distraction and problem-solving. In research, the response style 'rumination' has been found to have moderating effects on the relation between life events and depressive symptoms; adolescents with a rumination response style are more likely to experience depressive symptoms when reporting more life events [17
]. To study elevations in depressive symptoms as a consequence of cognitive distortions, longitudinal studies are needed so temporal sequences can be analyzed [18
]. Research on cognitive distortions using longitudinal designs is however very limited [19
]. We hypothesize that the OVK program will prospectively decrease the cognitive distortions of the adolescents and in turn will influence the reported depressive symptoms.
Another theoretical concept we expect to be highly relevant in relation to depression prevention programs is alexithymia. Alexithymia refers to difficulties in experiencing and verbalizing emotions and difficulties in emotional self-regulation [20
]. An impaired emotion processing ability is suggested to lead to negative mood states and support for this hypothesis is found with cross-sectional data: children who score higher on alexithymia are found to ruminate and worry more about emotion-evoking situations compared to children who score lower on alexithymia [21
]. Diminished alexithymia, in turn, is associated with a reduction of depressive symptoms, and although it is still unclear if cognitive behavioural therapy can reduce alexithymia, the first hopeful results are reported [22
]. We hypothesize that the OVK program leads to less alexithymia and subsequent lower levels of depressive symptoms.
The first goal of the current study is to test if the OVK program prevents symptoms of depression when the program is delivered by teachers during school hours to a whole class of adolescents. The second goal is to study the mechanisms and possible factors underlying the effects of the program.