Public attitudes toward depression and help-seeking: Impact of the OSPI-Europe depression awareness campaign in four European regions.

•New insights in visibility and effectiveness of a public awareness campaign across four European regions.•Less personal depression stigma in the intervention regions compared to control regions.•Aware respondents in the intervention region report more openness toward seeking professional help compared to control.•Findings exceed previous research regarding effects on help-seeking behaviour and distribution of intervention sites.•Public campaigns are effective means in reducing stigma as part of multi-level intervention programmes.