Prisoners with and without mental illness and community samples: detecting differences in aggression and psychopathic traits

The presence of people with mental illnesses in prisons is well-documented. However, the relationship between mental illness and aggressive behaviour within prison environments remains insufficiently understood. This study aims to examine the differences in aggression and psychopathic traits among three groups: prisoners with mental illness (PMI), prisoners with no mental illness (PNMI), and a community population group (CP). The sample comprised 165 adult males (18-65 years; M = 41.64, SD = 9.71), recruited from a Spanish prison and a community setting. Our results showed that within the prison population, the PMI subgroup scored significantly higher on various aggression subscales, including physical aggression, anger, and hostility, compared to the PNMI subgroup. Additionally, the PMI group exhibited greater impulsive aggression compared to the CP group. Regression analyses revealed a stronger association between psychopathic traits and aggression in the PMI group than in the other groups. These findings highlight that PMI show lower resilience and more pronounced psychopathic traits; in this context, these traits are associated with higher levels of aggression.