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Mental Illness- Does it make you more violent?
Tanvir Singh, MD,
Assistant Prof. Psychiatry
University of Toledo Medical Center, Toledo, Ohio, 43614
Abstract - The purpose of the paper is to review the literature on the relationship between mental illness and violence. It considers which subgroup of patients with mental illness carry more risk of violence than others. The article also considers the impact of public perception or misperception of this relationship, which can contribute to further victimization of mentally ill. Also reviews the contemporary status and the limitations in predicting the violence in mentally ill.
Key Words- “mental illness”, “violence,” “mental illness and violence”
Violence refers to acts of physical aggression against others. It is the sixth leading cause of death for the age group 15-44 and fifth leading cause of death for persons aged 10 to 60 years in the United States1-3. Many people who do survive from acts of violence, suffer physical injury and psychological consequences, which makes it amongst the 20 leading cause of disability.4
After the deinstitutionalization, even the people with severe mental illness live in the community5-6.The number of patients hospitalized for mental illness in US decreased from 237 per 100,000 persons in 1969 to 80 per 100,000 in 19987.Mean length of stay now is less than 10 days and is further going down as managed care rely increasingly on nonresidential care to reduce the health care costs.8
The year 1990, marked the start of decade of the brain9. The year also marked the beginning of contemporary era of research on link between mental illness and violence.10
Few decades ago it was thought that mentally ill were no more likely to be violent than non mentally ill.11 But this perception has changed as many recent studies have reported a modest association and now it is generally agreed that mentally ill are more prone to violence than general population.12-16 But what has remained unclear is the extent of this greater risk and how much it is modifiable or preventable. Purpose of this article is to review the literature about the complex relationship between mental illness and violence.
Mentally ill and violent Acts
Though for United States, there is no data available to look into rate of mental disorders in homicide offenders, but a study in Sweden did the psychiatric evaluation of the homicide offenders and found that 54% had diagnosis of personality disorders, 47% had substance use disorders, and 25% had schizophrenia, bipolar, or other type of psychosis.17 Another study in Sweden examined the crime registers and hospital records between periods 1988-2000 and calculated the number of violent crimes per 1000 persons, which would not have occurred if the risk factor of mental illness had been absent. The results from the study found the attributable risk for violent acts with mental illness to be around 5.2%.18 In other words it meant that if mentally ill people no longer exist in community, the violent crimes would be less by 5.2%. Swanson and others also did a study using self report data from the Epidemiological Catchment area (ECA) survey to assess the violence rate in people with and without mental illness. They found out that major mental disorders correlated with atleast five fold increase in rates of violence over a 1 year period, compared with rates among individuals with no disorder, and ten fold increase in violence was found in people with substance abuse disorders.19
DSM IV has diagnosis like conduct disorder and antisocial personality disorder (APD) which have direct association with crime and violence. They are in a way paradigm of aggressiveness, with violent acts being part of their diagnostic criteria.20 Prevalence rate for APD are 3% for males and less than 1% for females21-22 but they comprise around 20% of the prison population23 and between 33%-80% of the population of chronic criminal offenders24-25. And these individuals are thought to account for over 50% of all the crimes in US26-27. Conduct disorder increases the likelihood of developing APD in adult life and criminal population overlap with APD in more than one way.21-27
Psychosis and violence
Link and Steuve28 found that presence of certain psychotic symptoms (like others meant to do one harm, that others could control ones thought, or other could put thoughts into their head),which were characterized by them as TCO(threat/control/override)are good predictors of violence in psychotic patients .
Swanson and others29 replicated the findings later and found respondents with TCO symptoms were twice as likely to indulge in violent acts compared with patients who had other psychotic symptoms. Swanson et al30 in another study on 1410 schizophrenic patients reported 6 month prevalence of simple violence (assault without injury or weapon use) around 15.5%, with 3.6% showing serious violent behavior (assault resulting in injury or involving use of lethal weapon, or sexual assault).They found that positive psychotic symptoms like persecutory ideation, and history of childhood conduct problems, and victimization increased the risk of violence.
Birth cohort studies, have yielded significant (OR) odd ratios (increased risk) of violence in patients with psychotic disorders.31 Hodgins32 reported OR of 4 for males and 27 for females from his 30 year study of violence in mental disorders with psychosis, while Tiihonen and others33 in their study of 26 years reported OR of 7 for male subjects with schizophrenia and 23 in female subjects with schizophrenia.
Results from various studies are consistent to suggest that risk of violence in psychosis is more in case of female gender than male.34-36 Study36 done on 304 women with psychosis found 2 year prevalence of violent acts to be around 17% which is more than reported in males. Factors predicting violence in female gender in the study included past history of violence, substance use, African Caribbean descent, presence of personality disorders, and history of victimization..
Unlike many other studies, MacArthur study done on recently discharged patients from psychiatric hospitals, reported that if symptoms of substance abuse are excluded, no significant difference exist in prevalence of violence between discharged psychiatric patients and community control subjects.37 In one of the conclusion from the MacArthur study Steadman and others reported no significant relation between psychosis (with TCO Symptoms) and violence38
Substance abuse and violence
Substance abuse has been consistently reported as major risk factor for violence, both alone as well combined with mental health disorders.19,39-43 Swanson and others19 in their epidemiological catchment area (ECA) data study reported substance abuse as more significant variable for risk of violence than any major mental disorders. Fulwiler and colleagues39 studied patients in assertive community treatment program and found that substance abuse either alone or in combination with mental disorders significantly increased the chances of violent behavior. MacArthur study37 found no increase in rate of violence in mentally ill patients compared to general population if they were not using illicit drugs or alcohol. Swartz and others40 in their study found substance abuse and noncompliance with treatment as major predictors of violent behavior in mentally ill. Study done by Wallace and colleagues43 looked at the conviction rate of patients with schizophrenia for over 25 years and compared it with community sample. They found out that substance abuse in schizophrenic patients increased their risk of criminal conviction by sixteen fold.
One of the most challenging task has been to compare the prevalence of violence in patients with major mental disorder and substance use, to patients with mental disorders and no substance use. Study done by MacArthur Violence risk assessment team37 made intensive effort to distinguish the two and concluded that concurrent substance use simply doubled the risk of violence in the mentally ill patients.
Other factors and violence
Research supports presence of certain sociodemographic and environmental factors as risk factors for violence19,37,44-46. Swanson and others44 in 2002 did a study on a multistate sample of psychiatric patients with psychotic and mood disorders. They found environmental factors like homelessness and witnessing or experiencing violence in past as significantly contributing towards the risk of violence. Swanson and other ECA studies19 found that male sex(with no mental illness), young age, and low socioeconomic status were significantly more predictive of violent behavior than mental illness alone. Link and others45 found significant relation between educational level and violence. Study done by Silver and colleagues46 found that psychiatric patients discharged to neighborhoods of concentrated property further increased their risk of violence by 2.7 times.
Violent victimization of mentally ill
Many studies have supported the criminal and violent victimization of people with mental illness47-51 Deinstitutionalization increased the rate of homelessness in psychiatric patients which inturn has made people with mental illness more vulnerable to victimization.5-6 Study49 done on 270 acute inpatient psychiatric patients found that 15.2% of them had been physically assaulted, forced to have sex, threatened or attacked with weapon within the last 10 weeks. Another study48 done on 172 outpatient with schizophrenia found that 38% of the patients had been victimized in last 3 years and in 91% of cases the incident was violent in nature. Teplin et al51 did a study on 936 patients with mental illness and compared the crime and violent victimization with general population based on national crime victimization survey. They found the incidents of violent crimes in mentally ill patients to be four times higher than national crime victimization survey rates. And when they compare the psychiatric patients victimization rate with general population, results indicated that victimization rate depending on crime(rape/sexual assault, robbery, physical assault)was 6-23 times higher in people with mental illness.
Predicting violence in the mentally ill
Study52 in 1993, done on staff prediction of violence in nearly 2000 university psychiatric emergency departments reported that prediction accuracy had sensitivity of 60% and specificity of 58%. And patients who were predicted to become violent committed more serious acts of violence. Results also indicated significant underestimation of violence in female patients. When authors compared the accuracy with predictions made by history alone, sensitivity was 69% and specificity 48%.
Mossman53 looked into 44 already published studies of violent prediction and reanalyzed 58 data sets. He found no difference in short term or long term prediction of violence, and concluded that accuracy of prediction is definitely better than chance. He also reported better prediction in studies done after 1986 and suggested that past behavior was better predictor than clinical judgment alone. Several other studies54-57 have also looked into the prediction of violence by physician and other mental health staff and found mixed results. In one study54, clinicians were asked about which patients would become violent, under what circumstances, and what characteristics of violence would occur. Results showed that clinician did well in their predictions about place, target, severity of violence, and involvement of alcohol in violent acts, but overestimated the role of medication noncompliance, clinical condition, and drug use as associated factors. Study 55 done in Israel compared the ability of psychiatrists and nurses to predict inpatient violence among a sample of 308 admitted patients. Psychiatrists correctly classified the patients in 82% of cases, but this was mainly because of correct prediction of nonviolence rather than violent acts. Their specificity in prediction of violence was 88% but sensitivity was only 37%.
Instruments like Violence risk appraisal guide(VRAG)58 and Historical/clinical/risk management 20 item(HCR-20)59 have been developed, and their validity in predicting violence has received empirical support.60-61 But their main limitation has been the inability to reflect the change in clinical state of the psychiatric patients.31
Public mostly learn about mental illness from the media and movies.13,62-63 Unfortunately movies mostly depict psychiatric patients as dangerous and unpredictable.62 A Survey63 was done to look into public perception of relationship between mental illness and violence. It was found that public overestimates the risk of violence with mental illness. Results suggested that generally people associate random, senseless and unpredictable violence(attack by stranger in public place) with mental illness. Contrary to public perception the most likely victims of violence associated with mental illness have been found to be family members or friends, and violent acts perpetuated by mentally ill have typically occurred at home.37
MacArthur violence Risk Assessment Study37,64.
More than 1000 patients in acute civil psychiatric facilities were assessed by MacArthur study for more than 100 potential risk factors for violent behavior. Multiple measures of violence including patient self report were used, same neighbor comparison subjects were used to avoid any environmental bias
(1)Strong predictor of future violent behavior in people with mental illness after discharge from hospital is past violent and criminal behavior.
(2)History of physical abuse while growing up or exposure to environment of substance abuse as children results in higher rate of violence.
(3)Violent behavior is many times function of high crime neighborhoods, discharge patients reside, and not from mental illness
(4)Delusional symptoms even of violent content are not predictive of future violence in most of cases
(5)People with personality disorders and adjustment disorders are more prone to violent behavior than patients with schizophrenia and bipolar disorders.
(6)Comorbid substance use is vital in predicting violence
Results and discussion
Most of studies support that mental illness does moderately increase the risk of violence. And the presence of substance abuse, conflicted social relationships, poverty, and homelessness, makes people with mental illness even more vulnerable to respond in violent way. MacArthur study37 supports no role of mental health variables(if substance use is excluded) in distinguishing violent and non violent individuals, and in fact supports negative correlation between schizophrenia or presence of TCO symptoms and violence. One of the explanation could be that MacArthur study was done on patients just released from inpatient psychiatry hospital by natural decision of the clinician. Many experts31 believe that the contradictory results seen in MacArthur study might be due to successful psychiatric treatment received by the group before their discharge from the hospital. American Psychiatric Association also supports similar risk of violence in patients with mental illness compared to general population, but only if they are getting appropriate treatment. Positive impact of psychiatric treatment to reduce the risk of violence suggests more liberal use of policy of mandatory treatment adherence in patients recognized to be high risk for violence.
If one look into the factors associated with violence, substance abuse stands out as the most consistent and significant variable. Drug consumption has been believed to be responsible for increase in violence by several ways. The similarities in personality traits(like antisocial personality) that predispose to both drug consumption and acts of violence could be another reason for the association. Drug use decreases the inhibitions which facilitate patients to be violent and increase the chances of conduct concordant with content of delusions or hallucinations of violent theme. That is one reason there is such an important need to target substance use to reduce the risk of violent behavior.
We should not forget the association between mentally ill and violence when it comes to violent victimization of psychiatric patients. Violent victimization of psychiatric patients has unfortunately never received much public attention unlike the violence perpetuated by mentally ill. Victimization of mentally ill can also predispose them to react violently when provoked. A study66 showed that around half of mentally ill psychiatric patients retaliated with their own violent acts when victimized by other people.
Public perception plays a great role to determine how mentally ill would be treated in home, work, or in community. As the psychiatric hospitals continue to downsize the inpatient beds, media’s description of people with serious mental illness as “possible psycho killers” is going to make public feel very unsafe. And this presumption of violence may also serve as justification for violent victimization of mentally ill.
Though we are still in the learning process of how to predict violence in mentally ill. Current thinking can be summarized in McNeil and colleague’s observation61 that clinical factors(like intent, positive psychotic symptoms) are more important predictors of violence in acutely ill patient and past history of violence with certain socio-demographic factors more relevant in predicting long term risk.
It is universally agreed that majority of the mentally ill who are receiving appropriate treatment, do not carry more risk for violence than general population. Major determinants of violence include socio-demographic and socio-economic factors than just presence of mental illness. Mentally ill are also victims and not always perpetrator of violence. Early identification and treatment of substance use problems, especially if it occurs concurrent with mental illness can significantly reduce the risk of violence in mentally ill. Violence in female psychiatric patients(especially when psychotic) is underestimated.
Past history of violence and clinical judgment based on presenting symptoms are crucial in predicting potential violence in mentally ill. Greater funding and expansion of community based public mental health programs is needed. We also need more research on contextual determinants of violence to boost our violence prevention programs
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