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Summary - It is well known that the two major demographic predictors of violent behavior are male sex and younger age. It is also known that the two major clinical predictors of violent behavior are past history of violence and substance abuse (alcohol and/or drug). Recent studies have established that being severely mentally ill and not taking medication is a third major clinical predictor of violent behavior.
I. Severely mentally ill individuals who are taking their medication are not more dangerous than the general population.
The three-site MacArthur Foundation Study of violence and mental illness reported that discharged psychiatric patients without substance abuse had approximately the same incidence of violent behavior as other individuals living in the same neighborhoods. These patients were being followed closely for a year and most were taking their medications. The reported results were weakened by the fact that the patients with the most violent past histories were excluded from the study and the fact that the Pittsburgh neighborhoods used as controls were "disproportionately impoverished and had higher violent crime rates through the city as a whole."
Steadman HJ, Mulvey EP, Monahan J, et. al. Violence by people discharged from acute psychiatric impatient facilities and by others in the same neighborhoods. Archives of General Psychiatry 55:393-401, 1998.
II. Severely mentally ill individuals who are not taking their medication are more dangerous than the general population.
Several early studies in the 1970s suggested this fact but were not well controlled. For example, a 6-year follow-up of 301 patients discharged between 1972 and 1975 from a California state hospital reported that their arrest rate for "violent crimes" was 10 times the rate for the general population.
Sosowsky, L. Explaining the increased arrest rate among mental patients: A cautionary note. American Journal of Psychiatry 137:1602-1605, 1980.
In reviewing these earlier studies on discharged psychiatric patients, Dr. Judith Rabkin concluded: "Arrest and conviction rates for the subcategory of violent crimes were found to exceed general population rates in every study in which they were measured."
Rabkin J. Criminal behavior of discharged mental patients: A critical appraisal of the research. Psychological Bulletin 86:1-27, 1979.
The Epidemiological Catchment Area (ECA) surveys carried out in 1980-1983 reported much higher rates of violent behavior among individuals with severe mental illness living in the community compared to other community residents. For example, individuals with schizophrenia were 21 times more likely to have used a weapon in a fight.
Swanson JW, Hozer CD, Ganju VK, et. al. Violence and psychiatric disorder in the community: Evidence from the Epidemiologic Catchment Area surveys. Hospital and Community Psychiatry 41:761-770, 1990.
In a more recent analysis of data from the ECA study the authors noted that "mentally ill individuals with no treatment contact in the past 6 months had significantly higher odds of violence in the long term…moderate levels of agitation and psychoticism increase the risk of violence." They then conclude: "This would seem to provide a strong argument for providing more interventions targeted specifically to persons with combined mental illness and addictive disorders who are likely not to comply voluntarily with conventional outpatient therapies."
Swanson J, Estroff S, Swartz M, et. al. Violence and severe mental disorder in clinical and community populations: The effects of psychotic symptoms, comorbidity, and lack of treatment. Psychiatry 60:1-22, 1997.
A study of inpatients diagnosed with schizophrenia reported an inverse correlation between their propensity to violence and their blood level of antipsychotic medication.
Yesavage, J.A. Inpatient violence and the schizophrenic patient: An inverse correlation between danger-related events and neuroleptic levels. Biological Psychiatry 17:1331-1337, 1982.
A study of severely mentally ill patients in a state forensic hospital found a highly significant correlation (p< 0.001) between failure to take medication and a history of violent acts in the community.
Smith LD. Medication refusal and the rehospitalized mentally ill inmate. Hospital and Community Psychiatry 40:491-496, 1989.
A study in a forensic hospital in England reported an association between violent behavior and untreated psychotic symptoms. According to the authors "over 80 percent of the offenses of the psychotic [men] were probably attributable to their illness….Within the psychotic group those driven to offend by their delusions were most likely to have been seriously violent, and psychotic symptoms probably accounted directly for most of the very violent behavior."
Taylor P. Motives for offending amongst violent and psychotic men. British Journal of Psychiatry 147:491-498, 1985.
A 1990 study investigated violent behavior among severely mentally ill individuals in 1401 randomly selected families who were members of the National Alliance for the Mentally Ill (NAMI). In the preceding year 11 percent of these individuals were reported to have physically harmed another person.
Steinwachs DM, Kasper JD, Skinner EA. Family perspectives on meeting the needs for care of severely mentally ill relatives: A national survey. Arlington, VA: National Alliance for the Mentally Ill, 1992.
A 9 to 12 year follow-up of 192 men with schizophrenia who had been detained by the Secret Service when they had presented themselves at the White House with delusional demands found that they had a subsequent arrest rate for violent crimes 1.6 times (no past history of violence) to 4.8 times (with a past history of violence) the general population.
Shore D, Filson CR, Rae DS. Violent crime arrest rates of White House case subjects and matched control subjects. American Journal of Psychiatry 147:746-750, 1990.
A study of 133 outpatients with schizophrenia showed that "13 percent of the study group were characteristically violent." Having inadequately treated symptoms of delusions and hallucinations was one of the predictions of violent behavior. Specifically, "71 percent of the violent patients…had problems with medication compliance, compared with only 17 percent of those without hostile behaviors," a difference which was statistically highly significant (p< 0.001).
Bartels J, Drake RE, Wallach MA, et. al. Characteristic hostility in schizophrenic outpatients. Schizophrenia Bulletin 17:163-171, 1991.
A Swedish study of 644 individuals with schizophrenia followed for 15 years reported that they committed violent offenses at a rate four times greater than the general population.
Lindqvist P, Allebeck P. Schizophrenia and crime: A longitudinal follow-up of 644 schizophrenics in Stockholm. British Journal of Psychiatry 157:345-350, 1990.
Another Swedish study, using case registers, examined the criminal records of all individuals born in Stockholm in 1953 and still living there 30 years later. Men and women with a severe mental illness were 4.2 times (men) and 27.5 times (women) more likely to have been convicted of a violent crime compared to individuals with no psychiatric diagnosis.
Hodgins, S. Mental disorder, intellectual deficiency, and crime. Archives of General Psychiatry 49:476-483, 1992.
In a follow-up of patients released from a psychiatric hospital, Dr Henry Steadman et. al. reported that "27 percent of released male and female patients report at least one violent act within a means of four months after discharge."
Monahan J. Mental disorder and violent behavior. American Psychologist 47:511-521, 1992.
Among 20 individuals who pushed or tried to push another person in front of the subway in New York, all except one was severely mentally ill and offered motives directly related to their untreated psychotic symptoms.
Martell DA, Dietz PE. Mentally disordered offenders who push or attempt to push victims onto subway tracks in New York City. Archives of General Psychiatry 49:472-475, 1992.
In a carefully controlled study comparing individuals with severe mental illness living in the community in New York with other community residents, the former group was three times more likely to commit violent acts such as weapons use or "hurting someone badly." The sicker the individual, the more likely they were to have been violent.
Link BG, Andrews H, Cullen FT. The violent and illegal behavior of mental patients reconsidered. American Sociological Review 57:275-292, 1992.
A study of 538 individuals with schizophrenia living in London reported that the men had a 3.9 times and women 5.3 times greater risk for conviction for assault and serious violence compared to a control group with other psychiatric diagnoses.
Wesseley SC, Castle D, Douglas AJ, et. al. The criminal careers of incident cases of schizophrenia. Psychological Medicine 24, 483-502, 1994.
A study of 348 inpatients in a Virginia state psychiatric hospital found that patients who refused to take medication "were more likely to be assaultive, were more likely to require seclusion and restraint, and had longer hospitalizations."
Kasper JA, Hoge SK, Feucht-Haviar T, et. al. Prospective study of patients’ refusal of antipsychotic medication under a physician discretion review procedure. American Journal of Psychiatry 154:483-489, 1997.
A study in Switzerland compared 282 men with schizophrenia with a matched control group in the general population. The patients were five times more likely to have been convicted of violent crimes, mostly "assaults resulting in bodily harm." The more acutely ill the patient was, the more likely he was to have been violent.
Modestin J, Ammann R. Mental disorder and criminality: Male schizophrenia. Schizophrenia Bulletin 22: 69-82, 1996.
A study of homicides in Finland reported that "the risk of committing a homicide was about 10 times greater for schizophrenia patients of both genders than it was for the general population." For men "schizophrenia without alcoholism increased the odds ratio more than 7 times; schizophrenia with coexisting alcoholism more than 17 times."
Eronen M, Tiihonen J, Hakola P. Schizophrenia and homicidal behavior. Schizophrenia Bulletin 22:83-89, 1996.
In another study in Finland an unselected birth cohort of 11,017 individuals was followed for 26 years. Men with schizophrenia without alcoholism were 3.6 times more likely to commit a violent crime than men without a psychiatric diagnosis. Men with both schizophrenia and alcoholism were 25.2 times more likely to commit a violent crime.
Rasanen P, Tiihonen J, Isohanni M, et.al. Schizophrenia, alcohol abuse, and violent behavior: a 26-year follow-up study of an unselected birth cohort. Schizophrenia Bulletin 24:437-441, 1998.
In the three-site MacArthur Foundation Study of violence and mental illness referred to above, 17.4 percent of the patients were violent in the 10-week period prior to hospitalization, during which time they were not being treated, compared to an average of 8.9 percent for the five 10-week periods after hospitalization during which most of them were being treated.
Steadman HJ, Mulvey EP, Monahan J, et. al. Violence by people discharged from acute psychiatric inpatient facilities and by others in the same neighborhoods. Archives of General Psychiatry 55:393-401, 1998.
An English study of 1015 forensic patients with severe mental illness ("functional psychosis") reported that the diagnosis of "schizophrenia was most strongly associated with personal violence" and that "more than 75 percent of those with a psychosis were recorded as being driven to offend by their delusions." The authors concluded that "treatment appears as important for public safety as for personal health."
Taylor PJ, Leese M, Williams D, et. al. Mental disorder and violence. British Journal of Psychiatry 172:218-226, 1998.
A 10-year follow-up of 1056 severely mentally ill patients discharged from mental hospitals in Sweden in 1986 reported that "of those who were 40 years old or younger at the time of discharge, nearly 40 percent had a criminal record as compared to less than 10 percent of the general public." Furthermore, "the most frequently occurring crimes are violent crimes."
Belfrage H. A ten-year follow-up of criminality in Stockholm mental patients. British Journal of Criminology 38:145-155, 1998.
A study of 331 individuals with severe mental illness reported that 17.8 percent "had engaged in serious violent acts that involved weapons or caused injury." It also found that "substance abuse problems, medication noncompliance, and low insight into illness operate together to increase violence risk."
Swartz MS, Swanson JW, Hiday VA, et. al. Violence and severe mental illness: The effects of substance abuse and nonadherence to medication. American Journal of Psychiatry 155:226-231, 1998.
A study of 63 inpatients with schizophrenia in Spain reported that the best predictors of violent behavior were being sicker (i.e. higher scores on symptom measures) and less insight into their illness. "The single variable that best predicted violence was awareness into psychotic symptoms."
Arango C, Barba AC, Gonzalez-Salvador T, et. al. Violence in schizophrenic inpatients: A prospective study. Schizophrenia Bulletin, in press.
In reviewing many of these studies in 1992 Professor John Monahan concluded: "The data that have recently become available, fairly read, suggest the one conclusion I did not want to reach: Whether the measure is the prevalence of violence among the disordered or the prevalence of disorder among the violent, whether the sample is people who are selected for treatment as inmates or patients in institutions or people randomly chosen from the open community, and no matter how many social and demographic factors are statistically taken into account, there appears to be a relationship between mental disorder and violent behavior."
Monahan J. Mental disorder and violent behavior. American Psychologist 47:511-521,1992.
And in a 1996 editorial reviewing such studies Dr. Peter Marzuk added: "In the last decade, however, the evidence showing a link between violence, crime, and mental illness has mounted. It cannot be dismissed; it should not be ignored."
Marzuk PM. Violence, crime, and mental illness. Archives of General Psychiatry 53:481-486, 1996
III. Individuals with severe mental illnesses probably are responsible for no more than 5 percent of violent episodes in the United States.
Compared to substance abuse, severe mental illness contributes a relatively small percentage to total violence. Professor John Monahan cited a study that estimated "that 3 percent of the variance in violent behavior in the United States is attributable to mental disorder."
Monahan J. Mental illness and violent crime. National Institute of Justice Research Preview, October 1996.
A 1988 Department of Justice study reported that individuals with a history of mental illness (not including drug or alcohol abuse) were responsible for 4.3 percent of the homicides in the United States, or 897 out of 20,860. In instances in which the homicide occurred among family members the percentage was much higher, eg. in 25 percent of cases in which an individual killed his/her parent, that individual was mentally ill. If the 4.3 percentage held in 1993, the total mental illness-related homicides would have been 1,055 (4.3 percent of 24,530). It seems reasonable to assume that most of these would have been preventable if the individual had been receiving psychiatric treatment.
Dawson JM, Langan PA. Murder in families. U.S. Department of Justice, Office of Justice Programs, Bureau of Justice Statistics, 1994.
IV. At least 10 percent of males with severe mental illnesses become violent and a lesser percentage of females. In the United States this would total approximately 200,000 – 250,000 individuals.
There is very little data which can be used to estimate the percentage of severely mentally ill individuals who become violent. The best study used the Danish psychiatric case register, covering the whole country, and convictions for criminal offenses. Between1978 and 1990 6.7 percent of males and 0.9 percent of females with "major mental disorders" (psychoses) were convicted of a violent crime ("all offenses involving interpersonal aggression or a threat thereof"), compared with 1.5 percent males and 0.1 percent females among individuals with no psychiatric diagnosis. Since these are only convictions, it can be assumed that another unknown percentage committed a violent act for which they were not charged or convicted.
Hodgins S, Mednick SA, Brennan PA, et.al. Mental disorder and crime. Archives of General Psychiatry 53:489-496, 1996.
The incidence of violent behavior among severely mentally ill individuals in the studies discussed under II above includes:
11 percent in the survey of NAMI families
13 percent among outpatients with schizophrenia
8.9 percent in treatment and 17.4 percent not in treatment in the MacArthur Foundation Study
17.8 percent among inpatients with severe mental illness
In light of the above, it seems reasonable to estimate that at least 10 percent of males with a severe mental illness exhibit violent behavior at some time during their illness and a lesser percentage of females. Since there are at least 4 million individuals in the United States with schizophrenia and manic-depressive disorder, then approximately 200,000 – 250,000 severely mentally ill individuals are or have been violent.
V. Publicized episodes of violence by individuals with severe mental illnesses are a major cause of discrimination and stigma against this group.
Following highly publicized attacks on prominent German officials by individuals with severe mental illnesses, there was a measurable "marked increase in desired social distance from mentally ill people immediately following [the] violent attacks." The increased social distance and consequent stigma slowly decreased over time but had not returned to baseline two years later.
Angermeyer MC, Matschinger H. The effect of violent attacks by schizophrenic persons on the attitude of the public towards the mentally ill. Social Science and Medicine 43:12:1721-1728, 1996.
A study using university volunteers demonstrated that reading a newspaper article reporting a violent crime committed by a mental patient led to increased "negative attitudes toward people with mental illnesses."
Thorton JA, Wahl OF. Impact of a newspaper article on attitudes toward mental illness. Journal of Community Psychology 24:17-25, 1996.
Such studies suggest that it is futile to try and decrease stigma against individuals with mental illness until the problem of violence is addressed. This was noted as early as 1981 by Dr. Henry Steadman who observed:
"Recent research data on contemporary populations of ex-mental patients supports these public fears [of dangerousness] to an extent rarely acknowledged by mental health professionals. . . .It is [therefore] futile and inappropriate to badger the news and entertainment media with appeals to help destigmatize the mentally ill."
Steadman, HJ. Critically reassessing the accuracy of public perceptions of the dangerousness of the mentally ill. Journal of Health and Social Behavior 22. 31—316, 1981.
And in 1992 Dr. John Monahan added:
"The data suggest that public education programs by advocates for the mentally disordered along the lines of ‘people with mental illness are no more violent than the rest of us’ may be doomed to failure….And they should: the claim, it turns out, may well be untrue."
Monahan J. Mental disorder and violent behavior. American Psychologist 47:511-521, 1992.
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