Offenders with mental disorder : psychosocial and neurobiological aspects

Abstract

The main hypothesis of this thesis is that certain functions, or symptoms, in mentally disordered offenders are connected to biological correlates. There is no specific diagnosis that explains antisocial or violent behaviour. Among offenders some functions or symptoms are considered more common, such as impulsivity and reduced empathy. To date, biological factors related to antisocial and violent behaviour are still not fully understood. This is particularly true in the field of brain imaging, where research-findings are mixed and sometimes contradictive. Biological mechanism associated with antisocial and violent behaviour may have an impact on several forensic psychiatric areas, such as diagnostic assessments, provision of treatment options, risk assessment, and treatment evaluation. Therefore, increased knowledge of these biological factors will be important on many levels in forensic psychiatry and the criminal justice system. In this thesis mentally disordered offenders are studied, using a multi-dimensional approach, with parallel investigation of behaviour and peripheral physiology as well as brain structure and function. The findings imply that there are specific subgroups of offenders. These subgroups differ in crime scene behaviour, psychosocial functioning, and emotional processing, reflected by peripheral physiological reactivity as well as cerebral emotional processing.

In study I, crime scene behaviour was studied and the results suggest subgroups of offenders, with respect to differences in psychosocial factors and crime scene behaviour. In study II, emotional reactivity was investigated by measuring peripheral physiological reactivity in response to negative and neutral pictures. In this study, healthy controls and mentally disordered offenders, with different degrees of antisocial behaviour but without psychopathy, were studied. The offenders showed significant lower physiological reactivity in comparison to the controls. Moreover, the attenuated emotional reactivity was a characteristic shared by the offenders overall, thus antisocial behaviour was not a differential factor. In study III, cerebral structural changes were investigated. Cortical thickness was compared between a group of mentally disordered offenders with lack of empathy and healthy controls. The offender group showed thinner cortex in the frontal lobes bilaterally. Also, a negative correlation was found between scores on the psychopathy checklist and cortical thickness in the frontal lobes bilaterally, the right temporal lobe, and right hemisphere, suggesting that these areas are of importance in psychopathy. In study IV, emotional reactivity, reflected by cerebral functioning, was assessed with fMRI, during presentation of fearful and neutral facial expressions. Mentally disordered offenders were compared to healthy controls, moreover, two subgroups of offenders were also compared, the psychopathy group and the autism spectrum disorder group. The results indicated higher cerebral activity in specific brain areas in the mentally disordered offenders, implying altered perception and processing of fearful facial expressions in these subjects. Also, there were differences between the subgroups in the communication between the amygdala and other parts of the limbic system, suggesting that processing of fearful facial expressions differ in the two groups.

The results from this thesis suggest that biological factors, in addition to social and psychological factors should be considered in order to advance the understanding of different mechanism underlying antisocial and violent behaviour. Future studies are needed to confirm some of the findings, to further increase knowledge about these biological factors.