“…Assessments of the impact of gatekeeper training programmes are usually based on trained individuals completing questionnaires about their knowledge, their sense of their own competence, their skills, and sometimes their intentions to become engaged in preventive actions [16,17,20,25]. A number of literature reviews and meta-analyses [15,26–28] emphasise the lack of data on the efficacy of gatekeeper training programmes. There is a particular lack of data concerning elderly people [29], in contrast to the populations of adolescents and young adults [26,27,30–32], the military [14], employees in their workplace [20], and prisoners [33].…”