Perpetrator Prevention – Rahm/Joleby research group

We are a group specialized in clinical research with an overarching vision to prevent violence, with a specific focus on sexual violence against children. Our goal is to develop and evaluate pharmacological and psychotherapeutic treatment interventions for individuals at risk of committing abuse, with the hope of ultimately improving the quality and accessibility of highly specialized care.

Through interdisciplinary research methods, we aim to develop effective, safe, and scalable interventions, online and in the clinic. Our research is at the forefront of deepening the understanding of pedophilia neurobiologically and psychologically, as well as establishing evidence-based treatment methods.

Part of our research focuses on neuropsychiatric investigations, where brain imaging studies are used to explore the etiology of pedophilia and risk factors for committing abuse. The results from these studies have contributed to the understanding of pedophilia as part of a larger neuropsychiatric problem.

We also conduct pharmacological studies to investigate how medical treatments can be used to prevent sexual offenses in high-risk individuals. Our research shows that the testosterone suppressing medication degarelix can be effective in this context, and well appreciated by patients. Follow-up studies are now being planned to evaluate long-term effects.

A third line of research focuses on the development and evaluation of psychotherapeutic interventions. Our cognitive behavioral therapy program, Prevent It, available free and anonymously online, globally, has been shown to be effective in significantly reducing the amount of time anonymous individuals recruited via the Darknet viewed child sexual abuse material. This has led to the development and evaluation of several other related treatment programs conducted in multicenter trials and offered in nine different languages to closely examine the effectiveness of the interventions. Among other things, in Project Bridge we are testing motivational interviewing as a technique to increase likelihood of seeking healthcare for sexual impulses directed at children, and together with the Swedish Prison and Probation Services, cognitive behavioral therapy is being evaluated in prison. 

In the group, there is also a project on the implementation of violence prevention efforts within 24-hour psychiatric care, in a national collaborative project.

The research group is led by Christoffer Rahm, who is primarily responsible for conducting research activities, and Malin Joleby, who is responsible for personnel, work environment and finances.

Research Projects


In a pharmacological study , the effect of the testosterone-suppressing drug degarelix in reducing the risk of repeated sexual offenses against children in people with pedophile disorder was investigated for the first time. This double-blind, placebo-controlled, parallel-group RCT showed that degarelix reduces the risk of committing a sexual offense as early as two weeks after the first injection, providing support for the use of this drug as a rapid-onset treatment.

Within Priotab, in-depth interviews were also conducted in order to qualitatively study various aspects of the experience of having pedophilia and seeking care.

Contact person: Christoffer Rahm (principal examiner)

Funding: Swedish Medical Association, ALF funds, Fredrik and Inga Thuring Foundation, Gothenburg Medical Association, Center for Psychiatry Research

Collaboration partners: Kliniken Anova, Karolinska University Hospital

Prevent It

Prevent It is an anonymous Internet-delivered cognitive behavioral therapy to prevent child sexual abuse. The treatment program is nine weeks long, also available via the Darknet, and aims to help the participant learn to manage their sexual thoughts, feelings, and behaviors with the support of a therapist.

The first version of Prevent It has been scientifically evaluated in a placebo-controlled RCT, with recruitment from online offender forums, and found to be effective, safe and substantially appreciated by participants.

The program evaluation in follow-up studies is carried out in two pre-registered RCTs within the framework of the two projects: Global Perpetrator Prevention and PRIORITY. In these projects, Prevent it is available in both English, Swedish, German and Portuguese.

Contact persons: Allison McMahan and Malin Joleby, project coordinators. Christoffer Rahm (principal investigator)

Funding: EU (PRIORITY) Oak Foundation (Global Perpetrator Prevention), Swedish Medical Association (first version of Prevent it)

Financial and strategic partner: World Childhood Foundation (first version of Prevent it)

Collaboration partners: Universitaetsklinikum Hamburg-Eppendorf, Germany; Universidade do Porto, Portugal; Johns Hopkins Bloomberg School of Public Health, USA; Royal Ottawa Institute of Mental Health Research, Canada and Professor Gerhard Andersson's group at Linköping University, Sweden


Prevent-MED is a planned RCT evaluating the effectiveness of giving the testosterone-suppressing drug degarelix in addition to the Prevent It treatment program to participants with sexual problems that pose a risk to others. Can degarelix as an addition to psychological treatment reduce the risk of committing sexual abuse? Within Prevent-MED, new strategies are also being investigated to prevent and manage side effects of degarelix.

Contact person: Valdemar Landgren (principal examiner)

Funding: The Swedish Research Council

Partners: Correctional Service, Västra Götaland Region, Region Örebro, Region Stockholm, Forensic Psychiatry Växjö

Brain imaging of pedophilia and sexuality

Brain imaging with magnetic resonance imaging (MR), both 3T and 7T, both structural and functional imaging, is part of the PRIOTAB and Prevent-MED projects. The overall goal is to explore the neurobiology behind pedophilia and risk factors for committing sexual crimes.

Contact persons: Christian Mannfolk, Christoffer Rahm (main tester), Benny Liberg, Christoph Abé, Isabella Björkman-Burtscher

Funding: Fredrik and Ingrid Thurings Foundation, Professor Bror Gadelius Memorial Fund, Medical Society, Swedish Society for Medical Research, Söderström-Köningska Hospital Foundation, ALF funds

Collaboration partners: University of Gothenburg, Karolinska University Hospital Huddinge, Université de Lille, France

Project Bridge

Within Project Bridge, the following two treatment programs are evaluated:

ReDirection - An anonymous online self-help program based on cognitive behavioral therapy that focuses on helping people stop using child sexual abuse material.

Mi Bridge - Motivational Interviewing with a therapist via anonymous chat where the participant can explore their difficulties, their need for care and help to establish a contact with healthcare if the participant so wishes.

The treatment programs are available in Swedish, English, Finnish, German, Spanish, Czech and Slovak and are evaluated through two multicenter RCTs, based on pilot studies.

Contact persons: Maria Breide (project coordinator), Christoffer Rahm (principal investigator)

Funding: EU

Collaboration partners: Tobias Lundgren's research group; Suojellaan Lapsia, Protect Children ry, Finland; Universitat Jaume I De Castellon, Spain; Universitaetsklinikum Hamburg-Eppendorf, Germany; National Institute of Mental Health, Czech Republic; Akademia Policajneho Zboru V Bratislava, Slovakia; Professor Gerhard Andersson's group at Linköping University, Sweden

Preventing Sexual Abuse: CBT Programs for Convicted Men and Women in a Correctional Setting

The project aims to increase knowledge about recidivism prevention work among people convicted of sex crimes, by examining the programs Consent and SEIF that are conducted within the Swedish Correctional Service. Both programs are based on the principles of risk, need and susceptibility and are based on cognitive behavioral therapy. The projects include a mapping of treatment needs in the programs' target groups (men), an evaluation of Consent in an RCT (men) and a feasibility study (women).

Contact person: Johanna Lätth (project coordinator), Christoffer Rahm (principal tester)

Funding: The Correctional Service and the Crime Prevention Council

Collaborating partners: The Correctional Service


Violence and coercive measures in psychiatric round-the-clock care lead to an unsafe and damaged care and work environment for patients and staff. Safewards is an evidence-based program that can contribute to reducing violence and coercive measures by creating a sustainable and socially inclusive ward environment with patients and staff as creative co-creators. The project aims to evaluate the effects of introducing Safewards in Swedish psychiatric departments, as well as investigate which factors promote a successful implementation.

Contact person: Anna Björkdahl

Funding: AFA, FORTE, Red Cross University

Collaborating partners: Region Örebro


The high incidence of sexual abuse of children within the Catholic Church is a global problem that is receiving increasing attention. In this project, together with the Roman Catholic University of Rome, a culturally adapted version of the anonymous treatment program Prevent It will be developed with the aim of preventing sexual abuse of children within the Catholic Church.

Contact person: Christoffer Rahm (principal investigator), Allison McMahan (project coordinator)

Financial and strategic partner: World Childhood Foundation

Collaborators: Pontifica Universita Gregoriana, Rome, Italy

Project Nox

Within project Nox, the possibilities for new online-based infrastructure for global access to anonymous intervention programs are explored.

Contact person: Christoffer Rahm (principal investigator), Allison McMahan (project coordinator)

Financial and strategic partner: World Childhood Foundation



Selected publications

Lätth, J., Landgren, V., McMahan, A., Sparre, C., Eriksson, J., Malki, K., ... & Rahm, C. (2022). Effects of internet-delivered cognitive behavioral therapy on use of child sexual abuse material: A randomized placebo-controlled trial on the Darknet. Internet Interventions30, 100590.

Landgren, V., Malki, K., Bottai, M., Arver, S., & Rahm, C. (2020). Effect of gonadotropin-releasing hormone antagonist on risk of committing child sexual abuse in men with pedophilic disorder: a randomized clinical trial. JAMA psychiatry77(9), 897-905. 

Mannfolk, C., Liberg, B., Abé, C., & Rahm, C. (2023). Altered Neural and Behavioral Response to Sexually Implicit Stimuli During a Pictorial-Modified Stroop Task in Pedophilic Disorder. Biological Psychiatry Global Open Science, 3(2), 292-300. 

Abé, C., Adebahr, R., Liberg, B., Mannfolk, C., Lebedev, A., Eriksson, J., ... & Rahm, C. (2021). Brain structure and clinical profile point to neurodevelopmental factors involved in pedophilic disorder. Acta Psychiatrica Scandinavica, 143(4), 363-374. 

Landgren, V., Olsson, P., Briken, P., & Rahm, C. (2022). Effects of testosterone suppression on desire, hypersexuality, and sexual interest in children in men with pedophilic disorder. The World Journal of Biological Psychiatry, 23(7), 560-571. 

Landgren, V., Savard, J., Dhejne, C., Jokinen, J., Arver, S., Seto, M. C., & Rahm, C. (2022). Pharmacological treatment for pedophilic disorder and compulsive sexual behavior disorder: a review. Drugs, 82(6), 663-681. 

McMahan, A., Roche, K., Dreyhaupt, R., Seto, M. C., & Rahm, C. (2023). Changes in sexual thoughts and behaviors in a clinical sample of child sexual abuse material users under the COVID-19 pandemic. Sexual and Relationship Therapy, 1-21. 

Wittström, F., Långström, N., Landgren, V., & Rahm, C. (2020). Risk factors for sexual offending in self-referred men with pedophilic disorder: A Swedish case-control study. Frontiers in psychology, 11, 571775. 

Bayram, G., McMahan, A., Juth, N., & Rahm, C. (2023). Health care professionals’ view on pedophilic disorder: a qualitative study. Sexual and Relationship Therapy, 38(4), 684-695. 

Björkdahl, A., Johansson, U., Kjellin, L., & Pelto‐Piri, V. (2024). Barriers and enablers to the implementation of Safewards and the alignment to the i‐PARIHS framework–A qualitative systematic review. International Journal of Mental Health Nursing, 33(1), 18-36.

 Joleby, M., Lunde, C., Landström, S., & Jonsson, L. S. (2021). Offender strategies for engaging children in online sexual activity. Child Abuse & Neglect, 120, 105214. 

Joleby, M., Lunde, C., Landström, S., & Jonsson, L. S. (2020). “All of me is completely different”: Experiences and consequences among victims of technology-assisted child sexual abuse. Frontiers in psychology, 11, 606218. 


Staff and contact

Group leader

All members of the group


A fundamental principle in our research group's working method is to maintain close collaborations with the surrounding society, and we therefore strive to apply the principle of PPI (Patient and Public Involvement) in our projects. Our partners include the Swedish Police Agency, the Prison and Probation Service, the children's rights organization World Childhood Foundation Sweden, people with lived experience of pedophilia and people with their own exposure to sexual violence. Much of the research is conducted in collaboration with researchers at other universities in Sweden as well as abroad. See more information under the respective projects under the research project tab.