Mental disorder, psychological problems and terrorist behaviour: A systematic review and meta‐analysis

Abstract

Background: The link between mental health difficulties and terrorist behaviour has been the subject of debate for the last 50 years. Studies that report prevalence rates of mental health difficulties in terrorist samples or compare rates for those involved and not involved in terrorism, can inform this debate and the work of those responsible for countering violent extremism.Objectives: To synthesise the prevalence rates of mental health difficulties in terrorist samples (Objective 1-Prevalence) and prevalence of mental health disorders pre-dating involvement in terrorism (Objective 2-Temporality). The review also synthesises the extent to which mental health difficulties are associated with terrorist involvement compared to non-terrorist samples (Objective 3-Risk Factor).Search Methods: Searches were conducted between April and June 2022, capturing research until December 2021. We contacted expert networks, hand-searched specialist journals, harvested records from published reviews, and examined references lists for included papers to identify additional studies.Selection Criteria: Studies needed to empirically examine mental health difficulties and terrorism. To be included under Objective 1 (Prevalence) and Objective 2 (Temporality), studies had to adopt cross-sectional, cohort, or case-control design and report prevalence rates of mental health difficulties in terrorist samples, with studies under Objective 2 also needing to report prevalence of difficulties before detection or involvement in terrorism. For Objective 3 (Risk Factor) studies where there was variability in terrorist behaviour (involved vs. not involved) were included.Data Collection and Analysis: Captured records were screened in DisillterSR by two authors. Risk of bias was assessed using Joanna Briggs Institute checklists, and random-effects meta-analysis conducted in Comprehensive Meta-Analysis software.Results: Fifty-six papers reporting on 73 different terrorist samples (i.e., studies) (n = 13,648) were identified. All were eligible for Objective 1. Of the 73 studies, 10

Distinguishing lone from group actor terrorists: A comparison of attitudes, ideologies, motivations, and risks

“…Research by Spaaij [23] too, noted the frequent occurrence of psychological disturbance among lone actors, although this observation was based on a small sample. In contrast, a recent Campbell Systematic Review and meta‐analysis involving 73 different samples and 13,648 terror subjects [29] reported a life‐time prevalence rate of 17.4% for mental disorder and a pooled prevalence rate of 25.5% for studies reporting psychological problems and suspected disorder. In conclusion, the authors reported that, “this review does not support the assertion that terrorist samples are characterised by higher rates of mental health difficulties than would be expected in the general population (p. 2).”…”

Understanding (non)involvement in terrorist violence: What sets extremists who use terrorist violence apart from those who do not?

“…We are also reminded of two selection effects: one in which people with more socially oriented personalities seek the company of like‐minded individuals, and the other where (extremist) groups are likely to deny (continued) membership to individuals perceived as unreliable or erratic, whether as a result of limited social skills or mental health–related issues (Lindekilde et al., 2019). Arguably, such selection effects are part of the reason why mental health issues may be particularly prevalent among lone‐actor terrorists and less so group‐based ones (Sarma et al., 2022).…”

“…Whether mental health issues are associated with involvement in terrorism has long been subject to debate (Gill, Clemmow, et al., 2021). Recent meta‐analytical work finds that, excepting particular subpopulations (e.g., lone actors), those involved in terrorist violence exhibit unremarkable rates of diagnosed disorder or suspected disorder (Sarma et al., 2022). We contributed to this subject by collecting clinical information on the presence or absence of neurodevelopmental and mental health disorders, before and during radicalization.…”

Challenges to reintegration: a case study of violent extremist detainees and their reintegration into Malaysian society

“…Existing literature has explored the origins of terrorism, delving into their sociological and psychological aspects to gain a deeper understanding of the primary factors influencing their actions (Hudson, 1999). These studies had examined on the causality of terrorism whether in aspects of mental disorder, youth psychological vulnerabilities, immigration and various other factors that comes into such reasoning of their actions (Harpviken, 2020;Light and Thomas, 2021;Sarma et al, 2022). This is where the criminal justice systems are required to play their role in ensuring that such actions are penalised and offenders would not repeat such offences.…”