Forensic evaluation differs from mental health evaluation for clinical or treatment purposes in several aspects. Clinical evaluations aim at serving the healthcare needs of the individual, whereas forensic evaluators have legal goals that serve other parties 1.
Crime prevention effectiveness has always been one of the most important issues in the area of correctional and forensic psychiatric treatment. Politicians, media, and the public frequently discuss the issue, and clinicians and researchers in the field are often asked for answers. Recently, there have been important developments in the accuracy of assessments of risk for violence among individuals with mental disorders 2–7.
Most countries subject both psychiatrists and other medical practitioners in the field to special obligations for assessing the danger that individual patients pose to themselves and others. The ultimate purpose of such assessments is not prediction, but prevention. Prevention is of utmost importance as many studies suggest that although mental illness constitutes a risk factor for violent crime, a mentally ill individual has only a moderate risk of being prosecuted for such an offense 8.
Individuals with mental disorders are not similar to other groups in terms of the risk factors for violence. The strongest predictors are criminal history and personal demographic variables. Other established risk factors for violence in individuals with psychosis are comorbid substance misuse, active psychotic symptoms, noncompliance with medication, and comorbid personality disorder, particularly antisocial personality disorder 9–13.
Conceptualization of violence
There are different definitions of violence. One definition is that violence is actual, attempted, or threatened harm to an individual or individuals. A behavior that would be fear-inducing to the average individual may be counted as violence. Violence is a description of the act itself, not the damage to a victim. Examples of acts of violence include hitting, punching, kicking, etc. Less clear examples of violence may include kidnapping, arson, and reckless driving because of the threat of harming others 13.
All sexual assaults should be considered violent behavior. Boer et al.14 defined sexual violence as actual or attempted sexual contact with an individual who does not provide consent or who is unable to provide consent.
Sex difference and violence
When assessment techniques of the risk of violence are applied to women, there are particular concerns because of well-established sex differences in the quality, frequency, intensity, and etiology of violence 10,15–18. For example, the construct of psychopathy, which is consistently considered as an integral part of assessment of risk of violence, is different for men and women 19,20. Nonetheless, studies evaluating violence risk assessment measures typically either ignore sex or include male sex as a risk factor for violence 21.
The HCR-20 Violence Risk Assessment Scheme is one of the most frequently used and widely researched violence risk assessment tools 13. Research has shown that the HCR-20 has moderate to strong predictive accuracy in men across different populations and settings 22; however, the utility of the HCR-20 has not been conclusively established or even adequately investigated in women 23, with much of the support for this measure coming from a single research team 24.
A study of the predictive accuracy of HCR-20 has indicated that a number of significant differences were observed for individual items between men and women. These sex differences indicate that the individual risk factors for violence may differ in terms of their frequency, and hence may have a different impact on the process of violence risk assessments. Interestingly, there were no sex differences in the individual items with respect to predictive utility, suggesting that, when present, the same risk factors apply equally to men and women 25.
Violence in psychiatry
Violence and psychosis
In the 1980s, expert opinion suggested that there was no increased risk for violence in individuals with schizophrenia and other psychoses 26. However, with the publication of large population-based studies over the last two decades, it is now believed that there is a modest association between violence and schizophrenia and other psychoses 27. This view is not shared by many mental health clinicians 28 or public advocacy groups. In factsheets, the Schizophrenia and Related Disorders Alliance of America states that individuals with schizophrenia are no more likely to be violent than their neighbors 29, and SANE Australia states that individuals with mental illness who receive treatment are no more violent than others 30.
The issue remains topical because it is believed to have contributed toward policy and legal developments for psychiatric patients 31 and the stigma associated with mental illness 32, which is considered to be the most significant obstacle to the development of mental health services 33.
Although a number of studies have examined the relationship between psychoses and violent outcomes, wide variations in risk ratios have been reported, with estimates ranging from seven-fold increases in violent offending in schizophrenia compared with general population controls 34,35 to no association in a highly influential prospective investigation 36.
Four main findings were obtained by a systematic review of the risk of violence in schizophrenia and other psychoses that identified 20 studies including 18 423 individuals with these disorders. The first finding was that the risk of violent outcomes was increased in individuals with schizophrenia and other psychoses. A second finding was that comorbidity with substance use disorders increased this risk considerably. Although there was considerable variation in this estimate between studies, the pooled estimate was around four times higher compared with individuals without comorbidity. Third, the study found no significant differences in risk estimates for a number of study design characteristics for which there has been uncertainty. These included whether the diagnosis was schizophrenia versus other psychoses, whether the outcome measure was register-based arrests and convictions versus self-report, and whether the study location was the USA or Nordic countries compared with other countries. Finally, the increased risk of violence in schizophrenia and psychoses comorbid with substance abuse was not different from the risk of violence in individuals with diagnoses of substance use disorders. In other words, schizophrenia and other psychoses did not appear to add any additional risk to that conferred by the substance abuse alone 37.
The relationship between comorbid substance abuse and violence in schizophrenia may be mediated by personality features and/or social problems, and is unlikely to be a simple additive effect 38.
The relationship with medication adherence may also mediate the association with violent outcomes, particularly if it precedes substance abuse on the causal pathway to violence.
Other findings suggest that individuals with substance use disorders may be more dangerous than individuals with schizophrenia and other psychoses, and that psychoses comorbid with substance abuse may confer no additional risk over and above the risk associated with the substance abuse. As substance use disorders are three to four times more common than psychoses 39,40, public health strategies to reduce violence in society could focus on the prevention and treatment of substance abuse at individual, community, and societal levels 37.
Violence and mood disorders
Any association between mood disorders and violence has been comparatively overlooked. It appears that there may be more evidence relating mood disorders and violence than many clinicians realize. Most societal violence is not mediated by psychosis, being more often associated with anger or other extreme affective states, often interacting with disinhibitors such as intoxication. Therefore, it might be considered that mood disorders, with their prominent symptoms of dysphoria, irritability, and anger, and their intrinsic tendency to weaken internal inhibitions, would be associated with violence at least as much as schizophrenia. However, clinical experience may indicate that this is not the case, that violence in mood disorder is unusual 41.
Homicide–suicide describes the situation when an individual kills someone (often a spouse or a relative) and then takes their own life. In England and Wales, it is estimated that homicide–suicide accounts for 1% of all homicides 42. Homicide–suicide has been commonly associated with depression, and one case series found that 75% of perpetrators were depressed at the time 43.
Infanticide is the killing of a child by the mother before the first birthday, very commonly in the context of pos-partum depression 44. It may be distinguished from neonaticide (a baby being killed within the first day of life) and filicide (the killing of a child on or after its first birthday). Two motivational profiles have been identified: mothers who committed neonaticide were mostly troubled by psychosis and social problems and mothers who committed filicide were defined as severely depressed, with a history of self-directed violence and a high rate of suicide attempts following the filicidal offence 45.
In general, affective states, particularly anger and irritability, play a role in aggressive behavior and are influenced by serotonergic mechanisms. Extensive literature has suggested a link between decreased serotonin function and aggression, probably mediated through impulse control, affect regulation, and social functioning 46. The evidence relating to a clinical association between mood disorders and violence may consider the rate of violence in relation to inpatient treatment of depression, the rate of depression in violent or offender populations, and the rates of co-occurring depression and violence in the community. Most individuals with mental illness are not admitted to hospital and most individuals who behave violently are not convicted of a crime or put in prison. Therefore, research using inpatients and convicted offenders underestimates the rate of mental illness and violent behavior in the general population and potentially biases any findings about an association between mental illness and violence. For this reason, studies in the community are very helpful in elucidating any association 41.
The relationship between mood disorders and violence has been relatively overlooked compared with schizophrenia. It may be that comorbid substance misuse has a more significant impact on the risk of violence in mood disorders than in schizophrenia, which explains why in some studies the association between mood disorders and violence did not remain when comorbidity was controlled for. However, comorbidity is almost ever present in day-to-day clinical practice. It might not be appropriate to consider diagnoses in isolation, as is the case in research 41.
Personality pathology and violence
Research indicates a higher prevalence of personality disorder diagnoses in forensic psychiatric and correctional samples compared with samples from community settings 47. Personality disorder diagnoses made using validated assessment measures have been detected between 42 and 78% of adult male and female prisoners 48,49. Also utilizing validated assessment methods, research into mentally disordered offenders, many of whom have a history of violence, suggests that 66% of men 50 and 80% of women 51 have one or more personality disorder diagnoses.
Personality pathology is a critical factor in the risk of harm presented by some individuals. Yet, although multiple studies verify the co-occurrence of violence and personality disorder, the mechanism of this link is not well understood. Consequently, the role of personality pathology in explaining violence may be inadequately addressed – if at all – in the risk formulations that should generate the risk management plans that follow. Understanding personality pathology may improve the way in which past violence is understood and the potential for future violence explored and, as a consequence, more appropriate recommendations for risk management may be made 52.
Prediction of violence
Danger to others is in certain ways more complex and more emotionally charged than suicidality, because the danger threatens to involve innocent bystanders. This situation exerts a significant influence on the degree of risk the clinician can accept. Nevertheless, prediction of dangerousness is fundamentally an unreliable endeavor. Forensic psychiatrists are constantly challenged to balance the individual patient’s rights and freedoms against the safety of the society 53.
Prediction of violence has been shown repeatedly to be a difficult clinical task, and its accuracy has usually been deemed to be poor. Some researchers have proposed that actuarial methods, risk assessment on the basis of statistical data, can enhance clinical assessments of potential for violence, which have traditionally been based on reviews by multidisciplinary staff 54.
In other words, risk assessments can be carried out in a number of different ways. Two traditional methods for making decisions – clinical and actuarial models – have been discussed in the medical and behavioral science literatures and have been applied to violence risk assessment. The clinical method has been described as an ‘informal, ‘in the head,’ impressionistic, subjective conclusion, reached (somehow) by a human clinical judge’. In contrast, the actuarial method has been described as ‘a formal method’ that ‘uses an equation, a formula, a graph, or an actuarial table to arrive at a probability, or expected value, of some outcome’ 55.
Recent work has suggested that the influence of risk assessment tools appears to be growing in both general and forensic settings. For example, violence risk assessment is now recommended in clinical guidelines for the treatment of schizophrenia in the USA and the UK 56,57. In the USA, risk assessment tools are used routinely in the mental healthcare systems of the majority of the 17 states that have civil commitment laws 58.
Originally, only clinical, unstructured assessments were carried out, and then instruments and structured methods became increasingly popular in the 1970s. The use of a combination of instruments and structured interviews is now on the rise. This could be justified by the fact that actuarial predictions of future violence on the basis of static nonpsychiatric characteristics result in greater statistical accuracy than purely clinical methods, but the former are insensitive to the effects of treatment and do not inform clinical intervention in an established way 59.
Risk assessment tools aid in the identification and management of individuals at risk of harmful behavior. Because of the potential utility of such tools, researchers have developed many risk assessment instruments, the manuals for which promise high rates of construct and predictive validity 60. To date, no single risk assessment tool has been consistently shown to have superior ability to predict offending 61.
However, a recent meta-analysis found that the predictive validity of commonly used risk assessment measures varies widely. The findings suggest that the closer the demographic characteristics of the tested sample are to the original validation sample of the tool, the higher the rate of predictive validity. The meta-analysis also indicated that tools designed for more specific populations were more accurate in detecting individuals’ risk of future offending. Risk assessment tools were found to produce more valid risk predictions for older White individuals and possibly women 62.
Because of the wide variation in the predictive validity of risk assessment measures, and the difficult clinical challenge imposed, further review of risk assessment procedures in the light of the current clinical and legal system is mandatory.
Conflicts of interest
There are no conflicts of interest.
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