PROTOCOL: Mental disorder, psychological problems and terrorist behaviour: A systematic review

This is the protocol for a Campbell systematic review. The objectives are as follows: the first objective of the review (Objective 1—Prevalence) is to present a synthesis of the reported prevalence rates of mental health difficulties in terrorist samples. Where sufficient data is available, the synthesis will be sensitive to the heterogeneity of the terrorism phenomenon by exploring the rates of mental health difficulties for different forms of terrorism and for different terrorist roles (e.g., bombing, logistics, finance, etc.). The second objective (Objective 2—Temporality) will synthesise the extent to which mental health difficulties pre-date involvement in terrorism within prevalence studies. Finally, the third objective (Objective 3—Risk) aims to further establish temporality by examining the extent to which the presence of mental disorder is associated with terrorist involvement by comparing terrorist and non-terrorist samples.