Relationship between comorbidity and violence risk assessment in forensic psychiatry - the implication of neuroimaging studies.

Violence is an important social problem. Violence in the community has important social relevance for the political, criminal justice, and health care systems. Studies of homicide offenders have suggested a high prevalence of neurologic dysfunction due to organic brain damage such as traumatic brain injury, epilepsy and dementia have been observed to exhibit excessive violence. Moreover, violence in the mentally ill can be viewed as an important medical and mental health problem with significant implications for forensic psychiatry and the community. Although numerous previous studies showed that rate of violent behavior in the community is not much higher in patients with serious mental disorders (schizophrenia) than in healthy controls, that rate is substantially higher in patients with psychiatric comorbidity and substance abuse. A high proportion of patients in forensic psychiatric facilities are diagnosed with comorbidity, most often with schizophrenia, paranoid psychosis, organic brain syndrome, various personality disorders and comorbid substance abuse. These patients represent a high risk group for violence within forensic psychiatric facilities, and repetitive violent behavior in the community. Understanding the neurobiological basis of aggressive behavior clearly has important social and clinical implications. By introduction of neuroimaging studies (MRI, fMRI, PET, SPECT) as a useful tool in forensic psychiatry, the neurobiological aspect of violence is better understood. Previous studies have shown that individuals with frontotemporal brain dysfunction are frequently displaying antisocial behavior (disinhibition, impulsivity, lack of empathy) that justify the diagnosis of "acquired sociopathy/psychopathy". A correlation between the potential for impulsive aggression mediated by limbic brain structures, and the control of the aggression by frontotemporal brain regions has been shown. The individuals with such brain dysfunction have an increased risk of violent behavior and scored high on the Webster's and Hare's violence risk assessment scale. This article reviews the relationship between psychiatric comorbidity, violence risk assessment and neuroimaging in forensic psychiatry and showing the useful directions for future research, screening and prevention of violent behavior among mentally ill criminal offenders.