Campbell Collaboration

Countering Violent Extremism (CVE) Program Reviews

Published studies

  • Madriaza, P., Hassan, G., Brouillette-Alarie, S., Mounchingam, A. N., Durocher-Corfa, L., Borokhovski, E., Pickup, D., & Paillé, S. (2025). Exposure to hate in online and traditional media: A systematic review and meta-analysis of the impact of this exposure on individuals and communities. Campbell Systematic Reviews, 21, e70018. https://doi.org/10.1002/cl2.70018
  • Lewis, J., Marsden, S., Cherney, A., Zeuthen, M., Rahlf, L., Squires, C., & Peterscheck, A. (2024). Case management interventions seeking to counter radicalisation to violence and related forms of violence: A systematic review. Campbell Systematic Reviews, 20, e1386. https://doi.org/10.1002/cl2.1386
  • Vergani, M., Perry, B., Freilich, J., Chermak, S., Scrivens, R., Link, R., Kleinsman, D., Betts, J., & Iqbal, M. (2024). Mapping the scientific knowledge and approaches to defining and measuring hate crime, hate speech, and hate incidents: A systematic review. Campbell Systematic Reviews, 20, e1397. https://doi.org/10.1002/cl2.1397
  • Sydes, M., Hine, L., Higginson, A., McEwan, J., Dugan, L., & Mazerolle, L. (2023). Criminal justice interventions for preventing radicalisation, violent extremism and terrorism: An evidence and gap map. Campbell Systematic Reviews, 19, e1366. https://doi.org/10.1002/cl2.1366
  • Sarma, K. M., Carthy, S. L., & Cox, K. M. (2022). Mental disorder, psychological problems and terrorist behaviour: A systematic review and meta-analysis. Campbell Systematic Reviews, 18, e1268. https://doi.org/10.1002/cl2.1268
  • Windisch, S., Wiedlitzka, S., Olaghere, A., & Jenaway, E. (2022). Online interventions for reducing hate speech and cyberhate: A systematic review. Campbell Systematic Reviews, 18, e1243. https://doi.org/10.1002/cl2.1243
  • Wolfowicz, M., Hasisi, B., & Weisburd, D. (2022). What are the effects of different elements of media on radicalization outcomes? A systematic review. Campbell Systematic Reviews, 18, e1244. https://doi.org/10.1002/cl2.1244
  • Zych, I., & Nasaescu, E. (2022). Is radicalization a family issue? A systematic review of family-related risk and protective factors, consequences, and interventions against radicalization. Campbell Systematic Reviews, 18, e1266. https://doi.org/10.1002/cl2.1266
  • Wolfowicz, M., Litmanovitz, Y., Weisburd, D., & Hasisi, B. (2021). Cognitive and behavioral radicalization: A systematic review of the putative risk and protective factors. Campbell Systematic Reviews, 17, e1174. https://doi.org/10.1002/cl2.1174
  • Mazerolle, L, Cherney, A, Eggins, E, Hine, L, Higginson, A. Multiagency programs with police as a partner for reducing radicalisation to violence. Campbell Systematic Reviews, 2021, 17, e1162. https://doi.org/10.1002/cl2.1162
  • Carthy, SL, Doody, CB, Cox, K, O’Hora, D, Sarma, KM. Counter-narratives for the prevention of violent radicalisation: A systematic review of targeted interventions. Campbell Systematic Reviews, 2020; 16:e1106. https://doi.org/10.1002/cl2.1106. Watch a video presentation about this study on YouTube: click here.
  • Mazerolle, L, Eggins, E, Cherney, A, Hine, L, Higginson, A, Belton, E. Police programmes that seek to increase community connectedness for reducing violent extremism behaviour, attitudes and beliefs. Campbell Systematic Reviews. 2020; 16:e1111. https://doi.org/10.1002/cl2.1111. Watch a video presentation about this study on YouTube: click here.

Ongoing studies

Protocols

  • Valdebenito, S., Eisner, M. (2025). PROTOCOL: Interventions to Prevent Cognitive and Behavioural Violent Radicalisation: A Systematic Review and Multilevel Meta-Analysis. Campbell Systematic Reviews, 21 e70058 https://doi.org/10.1002/cl2.70058
  • Duarte, F. P., Ramos, J. P., Barbosa, P., Vergani, M., de Carvalho, C. M. (2025). PROTOCOL: Effectiveness of Educational Programmes to Prevent and Counter Online Violent Extremist Propaganda in English, French, Spanish, Portuguese, German and Scandinavian Language Studies: A Systematic Review. Campbell Systematic Reviews, 21, e70042. https://doi.org/10.1002/cl2.70042
  • Petrosino, A. & Morgan, C. (2025). PROTOCOL: Prevalence and Risk and Protective Factors for Radicalization Among School-Aged Youth: A Systematic Review. Campbell Systematic Reviews, 21: e70041. https://onlinelibrary.wiley.com/doi/10.1002/cl2.70041
  • Lewis, J., Marsden, S., Stefaniak, A., & Hewitt, J. (2025). PROTOCOL: Non-criminal justice interventions for countering cognitive and behavioural radicalisation amongst children and adolescents: A systematic review of effectiveness and implementation. Campbell Systematic Reviews, 21, e70020. https://doi.org/10.1002/cl2.70020
  • Marchment, Z., Clemmow, C., Gill, P. (2025). PROTOCOL: Situational Crime Prevention Measures to Prevent Terrorist Attacks Against Soft Targets and Crowded Places: An Evidence and Gap Map. Campbell Systematic Reviews, 21, e70040. https://doi.org/10.1002/cl2.70040
  • Hassan, G., Brouillette-Alarie, S., Braddock, K., Carthy, S., Varela, W., Madriaza, P., Gill, P. (2025). PROTOCOL: Government-Led Communication Campaigns for Reducing Violent Extremism − A Systematic Review. Campbell Systematic Reviews, 21: e70031. https://doi.org/10.1002/cl2.70031
  • Zych, I., & Marín-López, I. (2024). Risk and protective factors for child sexual abuse and interventions against child sexual abuse: An umbrella review. Campbell Systematic Reviews, 20, e70000. https://doi.org/10.1002/cl2.70000
  • Hassan, G., Brouillette-Alarie, S., Ousman, S., Madriaza, P., Varela, W., Danis, E., Kilinc, D., Pickup, D., Borokhovski, E., & CPN-PREV team. (2022). PROTOCOL: Are tools that assess risk of violent radicalization fit for purpose? A systematic review. Campbell Systematic Reviews, 18, e1279. https://doi.org/10.1002/cl2.1279

Titles

The following titles are reviews in progress. Protocols for these titles will be published in the journal Campbell Systematic Reviews.

  • Interventions targeting misinformation, disinformation and malinformation for reducing and countering violent extremism: A systematic review. Catia de Carvalho, João Pedro Ramos, Pedro Barbosa, Sarah Carthy, Marta Pinto. 9 June 2024.
  • Interventions for increasing trust in government in democratic contexts: A systematic review. Matteo Vergani, Zarina Vakhitova, Kathryn Benier, Kerry O’Brien, Haily Tran.
  • Primary interventions for cognitive and behavioural radicalization: An evidence and gap map. Kieren Aris, Meriem Rebbani, Joshua Freilich.

Countering Violent Extremism