Open Access

Background: Depressive disorders are highly prevalent and disabling diseases. Epidemiological studies have shown that they often co-occur with addictive behaviors, which in part might be explained by common risk factors. Rumination might be such a risk factor. Comorbidity can have substantial adverse effects for those affected. Thus, combined treatment approaches are needed. These should not be restricted to individuals with clinical disorders. In light of an apparent treatment gap, new treatment approaches that provide widespread access to evidence-based treatments need to be explored. In recent years, e-health interventions received a lot of attention. With their potential to be widely disseminated, they might be suitable to provide population-based intervention approaches. Developing population-based interventions might present special challenges to intervention developers, for example, in terms of intervention design or the selection of samples to preliminary test interventions. This thesis explored the application of e-health interventions in the treatment and prevention of depressive symptoms and addictive behaviors. Its first aim was to provide an overview on publicly accessible evidence-based e-health interventions for the treatment and prevention of depressive symptoms (study 1). The second aim was to test the feasibility, acceptability and potential effectiveness of a newly developed computer-based expert system intervention simultaneously targeting hazardous alcohol consumption and depressive symptoms and to investigate the importance of the sample selection when preliminary testing interventions (study 2). The third aim was to further investigate rumination with its subfactors brooding and reflection as a common cause of depression and addictive behaviors and thus as a potential target for combined interventions by analyzing its associations with symptoms of pathological gambling (SPGs; study 3). Methods: This thesis provides a summary of different working steps in the process of developing and testing a computer-based intervention for health care patients (HCPs) with comorbid hazardous alcohol consumption patterns and depressive symptoms. In study 1, a systematic literature search was conducted to identify evidence-based e-health interventions for depressive symptoms. Interventions were considered for further inspection if studies provided evidence for at least small intervention effects and if the interventions were accessible to at least selected groups of individuals. For study 2, 2773 consecutive HCPs were screened for hazardous drinking and depressive symptoms. Of the 41 HCPs who were offered to participate in the study, 27 (65.9%) consented. To investigate the importance of the sample selection when preliminary testing interventions, HCPs were compared to media recruited volunteers (MVs). Over a period of 6 months, study participants received 6 individualized counselling letters and weekly short messages. Pre-post data were analyzed for 30 participants (15 HCPs, 15 MVs). Intervention acceptability was assessed in post-intervention interviews conducted with 32 study participants. In study 3, cross-sectional data of 506 (80.4% male) individuals aged 14 to 64 years with a history of gambling problems were analyzed. Associations between the rumination subfactors and SPGs across different levels of problem gambling severity were investigated by means of sequential quantile regression. Results: In study 1, 37 publicly accessible evidence-based e-health interventions for depressive symptoms were identified. Most interventions (81.1%) were available in English. For the German language area, only 3 interventions were identified. In study 2, HCPs and MVs reduced regular binge drinking (HCPs: p = 0.016; MVs: p = 0.031) and depressiveness (HCPs: p = 0.020; MVs: p < 0.001). MVs further reduced average daily consumption (p = 0.034). Both subsamples rated the intervention positive. Compared to HCPs, MVs rated the alcohol module more favorably (p = 0.012). Intervention usage was higher in MVs than in HCPs (p = 0.013). Study 3 showed that at the median, ruminative brooding was positively associated with the severity of problem gambling after controlling for covariates (p = 0.005). Along the distribution of problem gambling severity, findings did hold for all but the lowest severity level. Ruminative reflection was not associated with problem gambling severity at the median (p = 0.347). Conclusions: E-health interventions show great potential in the treatment and prevention of depressive symptoms and addictive behaviors. However, more research is needed to clarify how to make the most of this potential. Important questions that remain to be answered include, for example, how to best provide e-health interventions to those in need or how to design interventions in order to maximize their reach and thus their public health impact. This thesis showed that 1) publicly accessible evidence-based e-health interventions for depressive symptoms were available. However, the supply in the German language area was low. 2) The computer-based expert system intervention targeting hazardous alcohol consumption and depressive symptoms was technically and logistically feasible, acceptable, and may have the potential to reduce hazardous drinking and depressive symptoms in different populations, including populations unselected in terms of their motivation to change. To avoid biased conclusions about the potential of interventions, intervention developers should preliminary test interventions on intended target populations. 3) Rumination might be important in the development and maintenance of addictive behaviors. With its relations to depression and addictive behaviors, it should be considered as a target for future combined interventions.

IntroductionThe co-occurrence of health risk behaviours (HRBs, ie, tobacco smoking, at-risk alcohol use, insufficient physical activity and unhealthy diet) increases the risks of cancer, other chronic diseases and mortality more than additively; and applies to more than half of adult general populations. However, preventive measures that target all four HRBs and that reach the majority of the target populations, particularly those persons most in need and hard to reach are scarce. Electronic interventions may help to efficiently address multiple HRBs in healthcare patients. The aim is to investigate the acceptance of a proactive and brief electronic multiple behaviour change intervention among general hospital patients with regard to reach, retention, equity in reach and retention, satisfaction and changes in behaviour change motivation, HRBs and health.Methods and analysisA pre–post intervention study with four time points is conducted at a general hospital in Germany. All patients, aged 18–64 years, admitted to participating wards of five medical departments (internal medicine A and B, general surgery, trauma surgery, ear, nose and throat medicine) are systematically approached and invited to participate. Based on behaviour change theory and individual HRB profile, 175 participants receive individualised and motivation-enhancing computer-generated feedback at months 0, 1 and 3. Intervention reach and retention are determined by the proportion of participants among eligible patients and of participants who continue participation, respectively. Equity in reach and retention are measured with regard to school education and other sociodemographics. To investigate satisfaction with the intervention and subsequent changes, a 6-month follow-up is conducted. Descriptive statistics, multivariate regressions and latent growth modelling are applied.Ethics and disseminationThe local ethics commission and data safety appointee approved the study procedures. Results will be disseminated via publication in international scientific journals and presentations on scientific conferences.Trial registration numberNCT05365269.