Recruitment. Participants will be recruited by means of advertisements in newspapers and through internet forums. The high-circulation newspapers are delivered for free in the Swiss public transport systems. Interested individuals in participation will contact the study office via SMS, e-mail or phone. Screened positive patients are invited for an intake assessment to verify the inclusion and exclusion criteria based on a standardized interview. Participants that are not screened positive are informed about more appropriate treatments via phone call or if requested by a further face-to-face contact.