The aim of the present thesis was to further explore psychological, social, and biological risk factors for criminal behavior and investigate the possibility that stress hyperreactivity (i.e., an excessively active stress response), as indexed by high scores on the Neuroticism personality trait, may mediate the impact of social, as well as biological, risk factors for antisocial behavior.
The thesis investigated the effects of low birth weight and being a client of Child Protective Services on criminal behavior, with a particular focus on the impact of being placed outside of the home, i.e., in foster care or an institution. Furthermore, the influences of genetic variance in monoamine oxidase A (MAOA), serotonin transporter (SLC6A4), and catechol-O-methyltransferase (COMT) genes on criminal behavior were investigated. The impacts of personality, the quality of relationship with caregivers, and having witnessed domestic violence were also examined. Finally, the thesis investigated possible explanations of why antisocial individuals have been found to score high on Neuroticism, indicating stress hyperreactivity, as well as sensation seeking, indicating stress hyporeactivity (i.e., an unusually diminished stress response). The thesis examined the possibility that high versus low scores on Neuroticism predict different types of sensation seeking.
The results showed that the personality factor of Neuroticism predicted a prosocial type of sensation seeking, with individuals working in a high-risk profession having high scores (i.e., high Emotional Stability) and inmates showing low scores. Furthermore, the MAOA polymorphism was related to criminal behavior and the COMT Val158Met polymorphism to sensation seeking. Having a poor relationship with caregivers predicted low scores on sensation seeking. Moreover, Neuroticism was observed to mediate the associations between the relationship with caregivers and the COMT Val158Met polymorphism and sensation seeking. Having witnessed domestic violence and being a client of Child Protective Services predicted an increased risk of criminal behavior. Finally, low birth weight interacted with placement in out-of-home care among clients of Child Protective Services to predict decreased risk of criminal behavior. In conclusion, this dissertation sheds further light on how psychological, social, and biological factors and their interrelationships may impact the development of criminal behavior. Disclosing vulnerability and resilience factors for antisocial behavior, the results may contribute to the detection of high-risk individuals and the formation of effective prevention policies.