STUDY PROTOCOL published: 05 November 2021 doi: 10.3389/fpsyg.2021.703624 Edited by: Richard John Gray, La Trobe University, Australia Reviewed by: Evangelia Karagiannopoulou, University of Ioannina, Greece Yang Wang, University of Maryland, Baltimore, United States *Correspondence: Célia M. D. Sales celiasales@fpce.up.pt Specialty section: This article was submitted to Psychology for Clinical Settings, a section of the journal Frontiers in Psychology Received: 30 April 2021 Accepted: 28 September 2021 Published: 05 November 2021 Citation: Sales CMD, Martins F, Alves MM, Carletto S, Conejo-Cerón S, da Silva LC, ˇ Cuš A, Edridge C, Ferreira N, Hancheva C, Lima EMA, Liverpool S, Midgley N, Moltrecht B, Moreno-Peral P, Morgan N, Mortimer R, Mota CP, Pietrabissa G, Sousa S, Ulberg R and Edbrooke-Childs J (2021) Patient and Public Involvement in Youth Mental Health Research: Protocol for a Systematic Review of Practices and Impact. Front. Psychol. 12:703624. doi: 10.3389/fpsyg.2021.703624 Patient and Public Involvement in Youth Mental Health Research: Protocol for a Systematic Review of Practices and Impact Célia M. D. Sales 1,2 * , Filipa Martins 1 , Marisa M. Alves 1 , Sara Carletto 3 , Sonia Conejo-Cerón 4 , Luis Costa da Silva 5,6 , Anja ˇ Cuš 7 , Chloe Edridge 5,6 , Nuno Ferreira 8 , Camellia Hancheva 9 , Esperanca M. A. Lima 1 , Shaun Liverpool 5,10 , Nick Midgley 5 , Bettina Moltrecht 5 , Patricia Moreno-Peral 4 , Nicholas Morgan 6 , Rose Mortimer 5 , Catarina Pinheiro Mota 5,11 , Giada Pietrabissa 12,13 , Sonia Sousa 14 , Randi Ulberg 15,16 and Julian Edbrooke-Childs 5,6 1 Faculty of Psychology and Education Science, University of Porto, Porto, Portugal, 2 Center for Psychology, University of Porto (CPUP), Porto, Portugal, 3 Department of Neuroscience “Rita Levi Montalcini”, University of Torino, Turin, Italy, 4 Biomedical Research Institute of Malaga (IBIMA), Málaga, Spain, 5 Evidence Based Practice Unit, University College London and Anna Freud National Centre for Children and Families, Clinical, Educational and Health Psychology, London, United Kingdom, 6 Child Outcomes Research Consortium, Anna Freud National Centre for Children and Families, London, United Kingdom, 7 Department of Child and Adolescent Psychiatry, Medical University of Vienna, Vienna, Austria, 8 Department of Social Sciences, University of Nicosia, Nicosia, Cyprus, 9 Sofia University St. Kliment Ohridski, Sofia, Bulgaria, 10 Faculty of Health, Social Care and Medicine, Edge Hill University, Ormskirk, United Kingdom, 11 University of Trás-os-Montes and Alto Douro, Vila Real, Portugal, 12 Department of Psychology, Catholic University of Milan, Milan, Italy, 13 Istituto Auxologico Italiano IRCCS, Psychology Research Laboratory, Milan, Italy, 14 School of Digital Technologies, Tallinn University, Tallinn, Estonia, 15 Division of Mental Health and Addiction, Institute of Clinical Medicine, University of Oslo, Oslo, Norway, 16 Department of Psychiatry at Diakonhjemmet Hospital, Oslo, Norway Various health settings have advocated for involving patients and members of the public (PPI) in research as a means to increase quality and relevance of the produced knowledge. However, youth PPI has been an understudied area. This protocol paper describes a new project that aims to summarize what is known about PPI with young people in mental health research. In line with the Preferred Reporting Items for Systematic reviews and Meta-Analyses Statement guidelines we will identify and appraise suitable articles and extract and synthesize relevant information including at least two reviewers at each stage of the process. Results will be presented in two systematic reviews that will describe (a) how youth PPI has been conducted (Review1) and (b) what impact youth PPI had on the subsequent research and on stakeholders (Review2). To our knowledge, this is the first set of reviews that uses a critical appraisal tool, which is co-developed with children and young people. Findings from this project will provide valuable insights and set out the key steps to adopting adequate PPI methods when involving children and young people in mental health research. Keywords: patient and public involvement, involvement in research, adolescents, young people, mental health Frontiers in Psychology | www.frontiersin.org 1 November 2021 | Volume 12 | Article 703624