Investigating the role of friendship interventions on the mental health outcomes of adolescents: a scoping review of range and a systematic review of effectiveness

Friendships are a crucial component of adolescence, though their role on adolescent mental health remains largely unexplored. This paper presents a scoping review, followed by a systematic review, to assess friendship interventions and their impacts on the mental health outcomes of adolescents aged 12-24. The scoping review intends to map the range of friendship interventions, while the systematic review intends to evaluate and categorise the efficacy of friendship interventions for mental health. Studies were selected using eight databases and screened for inclusion. Studies were included if they incorporated a friend or authentic social group in an intervention dedicated to improving mental health outcomes and well-being. Twenty-four studies were included in the scoping review, and 18 were eligible for the systematic review. Data from 12815 adolescents were analysed; three prominent themes emerged. The most common theme was mental health literacy, followed by supporting help-seeking and, finally, friendship-building and combating isolation. Most studies evaluated the individual who had received the intervention rather than their wider friends who would have been potential recipients of any altered interactions. Of the three included studies focusing on friendship building for mental health support, all had positive short-term outcomes but inconclusive long-term effects. Two studies brought in friends from an individual’s authentic social group to, for example, learn how to support their friend better. While the opportunities for improving mental health literacy and help-seeking seem to be strong, friends’ role in mental health interventions has only been developed in a few areas. It would benefit from broader domains of influence and mechanisms of action being explored, given how friends are proven to be a key point of contact for many adolescents.