Violent behavior in schizophrenic patients has serious clinical and societal consequences. In addition to the obvious harm to the victims, it also has profound effects on its perpetrators. Violent behavior is a frequent reason for psychiatric admission and prolongs hospital stays.1 It also constitutes an important barrier to appropriate community placement2,3 and is an obstacle for the successful reintegration of patients back into the community. As a result of deinstitutionalization, many of these patients live in the community but are homeless and frequently are involved with the criminal justice system.4 One study points out that the rise in criminality of the mentally ill coincides with far-reaching changes in the community care of those with serious mental disorder.5 Assessment of violence potential and treatment of violent behavior in people with schizophrenia are important areas for the clinician to consider.
Despite its importance, our understanding of violent behavior in schizophrenia remains fragmented. Research has been hampered by the implicit assumption that violence is a homogeneous phenomenon. Violent patients as a group are contrasted to nonviolent ones. However, the significance of various symptoms and other risk factors for violence will vary depending on the phase of the illness and on the presence of other underlying predispositions and risk factors. By grouping together dissimilar populations of violent patients with schizophrenia, one can mask important differences and as a result fail to identify essential risk factors for violence. The role of neurological impairment in violent behavior, for example, easily can be masked because some violent patients evidence greater neurological impairment than nonviolent schizophrenic patients, while others are less neurologically impaired than these patients.6
This article reviews various clinical symptoms associated with violence in schizophrenia, including psychotic symptoms and neurological impairment. Comorbidity with substance abuse and antisocial personality disorders play a significant role and are discussed as well. Another objective is to underscore the heterogeneity of violent behavior in schizophrenia; there are different types of violence with dissimilar underlying symptoms. Such an emphasis allows for more precise prediction of violence and more differentiated treatments.
Violence Associated with Psychotic Symptoms
An association between violence and positive psychotic symptoms (such as delusions, hallucinations, and conceptual disorganization) in patients with schizophrenia is well established in the literature7–9 and has already been extensively reviewed.10 This association, however, often is insufficiently characterized. To obtain a better understanding of the mechanisms by which these psychotic symptoms result in assault, we must examine temporal relationships between symptoms and violent behavior.
Many of the studies reporting an association between violence and positive symptoms have been carried out in the acute phase of the illness, in the period surrounding hospital admission, when these symptoms are most florid. The time course, however, rarely has been examined directly.10 In schizophrenia, many of the important symptoms and dispositional characteristics are not constant but change as a function of the course of the illness.11,12 Violence is associated with one set of variables early on in the patients' hospital stay, but with another set subsequently. Thus, excitement and hyperarousal are more common early on. Violence is accompanied by anger and agitation in newly admitted patients with schizophrenia13 but occurs in the relative absence of emotional turmoil later in their hospital stays.14 Thus, there are marked differences between the symptoms associated with violence present in acute psychotic decompensation and those associated with more enduring forms of violence.
Violence and Specific Psychotic Symptoms
Psychotic delusions are reported to play an important role in violence. In one study using the Epidemiologic Catchment Area data, the presence of delusions per se elevated the rate of reported violence fourfold.15 Specific types of delusions also may play a role in more persistent violence. Certain chronic or well-circumscribed delusions have been associated with higher risk of violence; these include delusions of being poisoned16 or syndromes of misidentification.17
Link and colleagues18 proposed that violence is more likely with threat control override symptoms — that is, when the patient has beliefs that there are people seeking to harm him or that outside forces are in control of his mind. These symptoms, however, were not associated an increased risk of violence in the McArthur violence risk assessment study.19 The reliance on self-report in previous studies may have resulted in the mislabelling of other phenomena that can contribute to violence as delusions.
Violence and Insight
Poor insight may play a role in violence. In one study, violent schizophrenic and schizoaffective patients had significantly less insight than nonviolent patients.20 Lack of insight can affect violence in different ways. It can have a more direct influence on patients' behavior because their inability to understand other people's actions and motivation leaves them more likely to interpret others' actions as malevolent.21 It can also affect violent behavior indirectly through compliance (or lack thereof) with treatment. Poor treatment compliance is associated with violence in multiple studies.22–24
Neurological Dysfunction and Violence
Violence has been associated with neurological and neurocognitive impairment as measured by a variety of methods, including neuropsychological25,26 and neurological27 tests. This connection is especially true of persistent violence28–30 in various patient populations. Abnormalities in brain function have been reported in brain imaging studies of violent people.31 Similarly, a high prevalence of EEG abnormalities have been reported in violent people, especially recidivist violent offenders.32
In violent patients with schizophrenia, this neurological impairment has remained poorly characterized; its mechanism of action and etiology are not understood. In a study conducted on a special unit for the management of violent behavior, neurological abnormalities differentiated recidivist violent patients from nonviolent or transiently violent schizophrenic patients.12 The recidivist violent patients evidenced impairments in higher motor and sensory integrative activity.
Neurological dysfunction affects the regulation of behavior. This is especially true of impairment in the inhibitory functions of the frontal lobes. It has been suggested that violence in frontally impaired patients is resistant to behavioral intervention due to the inability of such patients to use information concerning their own errors.33
Impairment of inhibitory function also is related to impulsivity. Recent literature has focused on impulsivity as a particularly relevant mechanism in the emergence of violent behavior.34 Additional information about the mechanisms through which neurological impairment results in violence was reviewed previously in this journal.35
Antisocial Traits, Psychopathy, and Violence
Antisocial traits, antisocial personality disorder, and psychopathy are strongly associated with violence and especially with violent recidivism in various populations. These include prison inmates, mentally disordered offenders, and both inpatient and outpatient civil psychiatric populations. In a meta-analysis of predictive longitudinal studies (from 1959 to 1995) examining predictors of violent recidivism for offenders with mental illness, antisocial personality disorder was the most significant clinical predictor.36
The importance of psychopathy as a predictor of violence in civil psychiatric samples was underscored by the MacArthur Violence Risk Assessment project.37 In a study using the data on 1,136 patients from that study followed in the community, the Psychopathy Checklist: Screening Version (PCL-SV) was the strongest clinical predictor of violence.38 Studies that are limited to patients with schizophrenia report similar findings; antisocial traits and psychopathy play an important role in violent behavior39 and particularly in violent recidivism.40
Aside from recidivism, the violence associated with psychopathy also is characterized by its severity. High comorbidity of psychopathy and schizophrenia have been reported in patients who showed severe violence.41 It is also qualitatively different; these patients commit premeditated violent crimes that are similar in their motivation to those committed by people who do not have mental illness.42
The Role of Substance Abuse
Substance abuse has been associated with violence in the general population43 and in psychiatric patients.44 In the MacArthur Violence Risk Assessment Study, the presence of a co-occurring substance abuse disorder was a key factor in community violence. Substance abuse is common among patients with schizophrenia; approximately half of patients with schizophrenic spectrum disorders meet criteria for a lifetime diagnosis of substance use problems.45 Schizophrenia with comorbid substance abuse increases the risk of violence compared with schizophrenia without substance abuse.46,47
Various mechanisms can account for the association between substance abuse and violence that are relevant to the three-dimensional model. Drug and alcohol abuse have disruptive effects on prefrontal function48 and on executive functioning. Impairments in neurocognitive function and especially in executive function play an important role in aggression related to substance use.49 Drug and alcohol consumption and impairments in executive functioning are related independently to aggressive behavior and have a compound interactive effect on such behavior.50 Substance abuse also has been associated with exacerbation of psychotic symptoms.51,52 There is also an association between psychopathy and substance abuse. Antisocial personality disorder within schizophrenia has been shown to be associated with greater concurrent substance use disorders.53,54
Differentiating Patterns of Violence in Schizophrenia
An important distinction in violence patterns, as mentioned above, is between transient and persistent forms of violence. Transient violence most commonly is detected in the period surrounding hospital admission. It is a common cause for hospitalization and is present early on during the hospital stay. Excitation and hyperarousal, prominent features of this presentation, easily escalate into violent behavior, but the latter resolves as the symptoms improve. These patients are less likely to present with a history of violent crime in the community.
Persistent violence has no clear time course. While it often is associated with neurological impairment,55 other factors are also present. When violent crime in the community was considered in addition to inpatient assaults to characterize more fully the violent behavior described in the study discussed earlier,6 patients with persistent inpatient violence combined with violent crime were found to differ markedly from patients with persistent inpatient violence but no violent crime in the community. The former had minimal neurological impairment, while the latter had prominent neurological dysfunction and persistent negative symptoms. The patients with crime in the community evidenced more severe hostility and suspiciousness.
Patients with neurological dysfunctions experience impairments in inhibitory control of violent behavior and in behavioral adaptability. Those who present with violent crime in the community have no problems with behavioral adaptability. The violence persists not for lack of control but because violence is viewed by its perpetrators as “adaptive.” The violence and hostility represent, therefore, well-ingrained patterns of antisocial behaviors.
A More Differentiated Approach to Violence
Different psychological and biological predispositions may underlie different forms of violence. The distinction between more disinhibited or impulsive behaviors and more antisocial behaviors receives support from the literature. In several imaging studies, prefrontal abnormalities were associated with impulsive, emotionally charged aggression as opposed to premeditated or predatory aggression.56,57 These different biological predispositions may interact to produce the various behavioral phenotypes.
Our ability to identify patterns of violence in schizophrenia also has important implications for the prevention, control, and modification of aggressive behavior in schizophrenic patients. Distinguishing among the dimensions of underlying violence will make it possible to develop targeted pharmacologic and behavioral therapies to each component of the violence domain in schizophrenia.
In treating violence that is associated with hyperarousal, the clinician must address the underlying excitement and acute positive symptoms. Typical antipsychotic agents, the mainstay of the management of violence in schizophrenia, usually are effective in the treatment of this violent behavior. Supplementation with other agents may speed up the process. Some studies have suggested that aggressive symptoms associated with hyperarousal respond well to divalproex,58 but these were conducted in bipolar patients.
Typical antipsychotic agents, while quite important in treating psychotic excitation, play a more limited role in the treatment of violence that is associated with neurological impairment or with psychopathy. These agents do not address the basic underlying deficits for these behaviors. The newer antipsychotic agents may be more useful in this respect.59,60 Disinhibited or impulsive violence may respond to antiepileptics; thus, phenytoin reduced impulsive, but not premeditated, aggressive acts in prisoners.61
In addition to treatment with specific psychopharmacologic agents, a more differentiated therapeutic approach can include behavioral techniques directed at the specific impairments underlying the violence. For example, to counter the impaired processing of feedback associated with neurological dysfunction present in the “disinhibited dimension,” improving cognitive functioning is of great importance. Specific interventions, such as the use of cueing, designed to exaggerate the link between stimulus and response, may be beneficial.62 Similarly, these patients may respond to a high degree of structure, supervision, and specific environmental modifications.63 Techniques such as cognitive-behavior therapy may be useful for the chronic characterological deficits present in the “antisocial dimension.” Cognitive remediation therapies would be of little use for violence associated with hyperarousal. Interventions aimed at preventing, decreasing, or counteracting a high level of arousal are of great importance.
In addition to pharmacologic treatment, the patients may further be helped with anger management and various coping techniques in response to interpersonal provocations. Such an approach would allow treatments to be tailored according to the dominant underlying mechanism of vulnerability.
- Lelliott P, Wing J, Clifford P. A national audit of new long-stay psychiatric patients. I: Method and description of the cohort. Br J Psychiatry. 1994;165(2):160–169. doi:10.1192/bjp.165.2.160 [CrossRef]7953029
- Bigelow DA, Cutler DL, Moore LJ, McComb P, Leung P. Characteristics of state hospital patients who are hard to place. Hosp Community Psychiatry. 1988;39(2):181–185.3345982
- Greenfield TK, McNiel DE, Binder RL. Violent behavior and length of psychiatric hospitalization. Hosp Community Psychiatry. 1989;40(8):809–814.2759570
- Borzecki M, Wormith JS. The criminalization of psychiatrically ill people: a review with a Canadian perspective. Psychiatr J Univ Ott. 1985;10(4):241–247.3911240
- Coid B, Lewis S, Reveley AM. A twin study of psychosis and criminality. Br J Psychiatry. 1993;162:87–92. doi:10.1192/bjp.162.1.87 [CrossRef]8425145
- Krakowski M, Czobor P, Chou JC. Course of violence in patients with schizophrenia: Relationship to clinical symptoms. Schizophrenia Bull. 1999;25(3):505–517. doi:10.1093/oxfordjournals.schbul.a033397 [CrossRef]
- Tardiff K, Sweillam A. Assault, suicide and mental illness. Arch Gen Psychiatry. 1980;37(2):164–169 doi:10.1001/archpsyc.1980.01780150054005 [CrossRef]7352848
- Yesavage JA. Inpatient violence and the schizophrenic patient: A study of Brief Psychiatric Rating Scale scores and inpatient behavior. Acta Psychiatr Scand. 1983;67(5):353–357. doi:10.1111/j.1600-0447.1983.tb00352.x [CrossRef]6869042
- McNiel DE, Binder RL. The relationship between acute psychiatric symptoms, diagnosis, and short-term risk of violence. Hosp Community Psychiatry. 1994;45(2):133–7.8168791
- Krakowski M, Volavka J, Brizer D. Psychopathology and violence: a review of literature. Compr Psychiatry. 1986;27(2):131–148. doi:10.1016/0010-440X(86)90022-2 [CrossRef]3514114
- Krakowski M, Czobor P. Violence in psychiatric patients: the role of psychosis, frontal lobe impairment and ward turmoil. Compr Psychiatry. 1997;38(4):230–236. doi:10.1016/S0010-440X(97)90031-6 [CrossRef]9202880
- Krakowski MI, Convit A, Jaeger J, Lin S, Volavka J. Neurological impairment in violent schizophrenic inpatients. Am J Psychiatry. 1989;146(7):849–853. doi:10.1176/ajp.146.7.849 [CrossRef]2631695
- Craig TJ. An epidemiologic study of problems associated with violence among psychiatric inpatients. Am J Psychiatry. 1982; 139(10):1262–1266. doi:10.1176/ajp.139.10.1262 [CrossRef]7124976
- Planansky K, Johnston R. Homicidal aggression in schizophrenic men. Acta Psychiatr Scand. 1977;55(1):65–73. doi:10.1111/j.1600-0447.1977.tb00141.x [CrossRef]842384
- Swanson JW, Holzer CE, Ganju VK, Jono RT. Violence and psychiatric disorder in the community: evidence from the Epidemiologic Catchment Area surveys. Hosp Community Psychiatry. 1990;41(7):761–770.2142118
- Humphreys MS, Johnstone EC, MacMillan JF, Taylor PJ. Dangerous behavior preceding first admissions for schizophrenia. Br J Psychiatry. 1992;161:501–505. doi:10.1192/bjp.161.4.501 [CrossRef]1393336
- Silva JA, Sharma KK, Leong GB, Weinstock R. Dangerousness of the delusional misidentification of children. J Forensic Sci. 1992;37(3):830–838.1629675
- Link HG, Andrews H, Cullen FT. The violent and illegal behavior of mental patients reconsidered. Am Sociological Rev. 1992;57(3): 275–292. doi:10.2307/2096235 [CrossRef]
- Appelbaum PS, Robbins PC, Monahan J. Violence and delusions: data from the MacArthur violence risk assessment study. Am J Psychiatry. 2000;157(4):566–572. doi:10.1176/appi.ajp.157.4.566 [CrossRef]10739415
- Arango C, Calcedo BA, Gonzalez-Salvador T, Calcedo OA. Violence in inpatients with schizophrenia: 1 prospective study. Schizophr Bull. 1999;25(3);493–503. doi:10.1093/oxfordjournals.schbul.a033396 [CrossRef]10478784
- McEvoy JP, Freter S, Everett G, et al. Insight and the clinical outcome of schizophrenic patients. J Nerv Ment Dis. 1989;177(1):48–51. doi:10.1097/00005053-198901000-00008 [CrossRef]2535871
- Swartz M, Swanson J, Hiday V, Borum R, Wagner H, Burns B. Violence and severe mental illness: the effects of substance abuse and nonadherence to medication. Am J Psychiatry. 1998;155(2):226–231.9464202
- 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. 1997;60(1):1–22. doi:10.1080/00332747.1997.11024781 [CrossRef]9130311
- Bartels SJ, Drake RE, Wallach MA, Freeman DH. Characteristic hostility in schizophrenic outpatients. Schizophr Bull. 1991;17(1): 163–171. doi:10.1093/schbul/17.1.163 [CrossRef]2047786
- Yeudall LT, Fromm-Auch D, Davies P. Neuropsychological impairment of persistent delinquency. J Nerv Ment Dis. 1982;170(5): 257–265. doi:10.1097/00005053-198205000-00001 [CrossRef]7069411
- Spellacy F. Neuropsychological differences between violent and nonviolent men. J Clin Psychol. 1978;34(1):49–52. doi:10.1002/1097-4679(197801)34:1<49::AID-JCLP2270340109>3.0.CO;2-0 [CrossRef]641182
- Lewis DO, Pincus JH, Bard B, et al. Neuropsychiatric, psychoeducational, and family characteristics of 14 juveniles condemned to death in the United States. Am J Psychiatry. 1988;145(5):584–589. doi:10.1176/ajp.145.5.584 [CrossRef]3358463
- Yeudall LT. Neuropsychological concommitants of persistent criminal behavior. Research Bulletin #29. Alberta Hospital, Edmonton, Alberta Canada; 1979.
- Monroe RR, Hulfish B, Balis G, et al. Neurologic findings in recidivist aggressors. In: Shagass C, Gershon S, Friedhoff AJ, eds. Psychopathology and Brain Dysfunction. New York, NY: Raven Press; 1977:241–253.
- Williams D. Neural factors related to habitual aggression: Consideration of differences between those habitual aggressives and others who have committed crimes of violence. Brain. 1969;92(3):503–520. doi:10.1093/brain/92.3.503 [CrossRef]5806125
- Raine A, Buchsbaum MS, Stanley J, et al. Selective reductions in prefrontal glucose metabolism in murderers. Biol Psychiatry. 1994;36(6):365–73. doi:10.1016/0006-3223(94)91211-4 [CrossRef]7803597
- Milstein V. EEG topography in patients with aggressive violent behavior. In: Moffitt TE, Mednick SA. Biological Contributions to Crime Causation. Dordrecht, Germany: Martinus Nijhoff; 1988:40–54. doi:10.1007/978-94-009-2768-1_3 [CrossRef]
- Teuber HL. Neuropsychology: effects of focal brain lesions. Neuroscience Research Program Bulletin. 1972;10(4):381–384.
- Barrat ES. Impulsiveness and aggression. In: Monahan J, Steadman H, eds. Violence and Mental Disorders: Developments in Risk Assessment. Chicago, IL: University of Chicago Press; 1994:61–79.
- Krakowski M. Neurologic and neuropsychologic correlates of violence. Psychiatric Ann. 1997;27(10):674–678. doi:10.3928/0048-5713-19971001-07 [CrossRef]
- Bonta J, Hanson K, Law M. The prediction of criminal and violent recidivism among mentally disordered offenders: A meta-analysis. Psychological Bull. 1998;123(2):123–142. doi:10.1037/0033-2909.123.2.123 [CrossRef]
- Steadman HJ, Mulvey EP, Monahan J, et al. Violence by people discharged from acute psychiatric inpatient facilities and by others in the same neighborhoods. Arch Gen Psychiatry. 1998;55(5):393–401. doi:10.1001/archpsyc.55.5.393 [CrossRef]9596041
- Skeem JL, Mulvey EP. Psychopathy and community violence among civil psychiatric patients: results from the MacArthur Violence Risk Assessment Study. J Consult Clin Psychol. 2001;69(3):358–74. doi:10.1037/0022-006X.69.3.358 [CrossRef]11495166
- Hodgins S, Lapalme M, Toupin J. Criminal activities and substance use of patients with major affective disorders and schizophrenia: a 2-year follow-up. J Affect Disord. 1999;55(2–3),187–202. doi:10.1016/S0165-0327(99)00045-2 [CrossRef]
- Tengstroem A, Grann M, Langstrom N, Kullgren G. Psychopathy (PCL-R) as a predictor of violent recidivism among criminal offenders with schizophrenia. Law Hum Behav. 2000;24(1):45–58. doi:10.1023/A:1005474719516 [CrossRef]
- Rasmussen K, Levander S. Symptoms and personality characteristics of patients in a maximum security psychiatric unit. Int J Law Psychiatry. 1996;19(1):27–37. doi:10.1016/0160-2527(95)00018-6 [CrossRef]8929657
- Harris GT, Varney GW. A ten-year study of assaults and assaulters on a maximum security psychiatric unit. J Interpersonal Violence. 1986;1(2):173–191. doi:10.1177/088626086001002003 [CrossRef]
- Chermack ST, Blow FC. Violence among individuals in substance abuse treatment: the role of alcohol and cocaine consumption. Drug Alcohol Depend. 2002;66(1):29–37. doi:10.1016/S0376-8716(01)00180-6 [CrossRef]11850133
- Swanson JW. Mental disorder, substance abuse, and community violence: an epidemiological approach.n: Monahan J, Steadman H, eds. Violence and Mental Disorders: Developments in Risk Assessment. Chicago, IL: University of Chicago Press; 1994:101–136.
- Regier DA, Farmer ME, Rae DS, et al. Comorbidity of mental disorders with alcohol and other drug abuse: results from the Epidemiologic Catchment Area (ECA) Study. JAMA. 1990;264(19):2511–2518. doi:10.1001/jama.1990.03450190043026 [CrossRef]2232018
- Cuffel BJ, Shumway M, Chouljian TL, Mac-Donald T. A longitudinal study of substance use and community violence in schizophrenia. J Nerv Ment Dis. 1994;182(12):704–708. doi:10.1097/00005053-199412000-00005 [CrossRef]7989915
- Smith J, Hucker S. Schizophrenia and substance abuse. Br J Psychiatry. 1994;165(1): 13–21. doi:10.1192/bjp.165.1.13 [CrossRef]7953023
- Pihl R, Peterson J, Lau M. A biosocial model of the alcohol-aggression relationship. J Stud Alcohol Suppl. 1993;11:128–139. doi:10.15288/jsas.1993.s11.128 [CrossRef]8410954
- Chermack S, Giancola P. The relationship between alcohol and aggression: an integrated biopsychosocial approach. Clin Psychol Rev. 1997;17(6):621–649. doi:10.1016/S0272-7358(97)00038-X [CrossRef]9336688
- Giancola P. Evidence for dorsolateral and orbital prefrontal cortical involvement in the expression of aggressive behavior. Aggressive Behav. 1995;21(6):431–450. doi:10.1002/1098-2337(1995)21:6<431::AID-AB2480210604>3.0.CO;2-Q [CrossRef]
- Dixon L, Haas G, Weiden P, Sweeney J, Francis A. Acute effects of drug abuse in schizophrenic patients: Clinical observations and patients' self-reports. Schizophr Bull. 1990;16(1):69–79. doi:10.1093/schbul/16.1.69 [CrossRef]2185536
- Mueser KT, Bellack AS, Blanchard JJ. Comorbidity of schizophrenia and substance abuse: Implications for treatment. J Consult Clin Psychol. 1992;60(6):845–856. doi:10.1037/0022-006X.60.6.845 [CrossRef]1460148
- Caton CL, Shrout PE, Eagle PF, Opler LA, Felix A. Correlates of codisorders in homeless and never homeless indigent schizophrenic men. Psychol Med. 1994;24(3): 681–688. doi:10.1017/S0033291700027835 [CrossRef]7991750
- Mueser KT, Drake RE, Ackerson TH, et al. Antisocial personality disorder, conduct disorder, and substance abuse in schizophrenia. J Abnorm Psychol. 1997;106(3):473–477. doi:10.1037/0021-843X.106.3.473 [CrossRef]9241949
- Krakowski M, Czobor P. Clinical symptoms, neurological impairment, and prediction of violence in psychiatric patients. Hosp Community Psychiatry. 1994;45(7):700–705.7927295
- Raine A, Meloy JR, Bihrle S, et al. Reduced prefrontal and increased subcortical brain functioning assessed using positron emission tomography in predatory and affective murderers. Behav Sci Law. 1998;16(3):319–332. doi:10.1002/(SICI)1099-0798(199822)16:3<319::AID-BSL311>3.0.CO;2-G [CrossRef]9768464
- Volkow ND, Tancredi LR, Grant C, et al. Brain Glucose metabolism in violent psychiatric patients: a preliminary study. Psychiatry Res. 1995;61(4):243–253. doi:10.1016/0925-4927(95)02671-J [CrossRef]8748468
- Swann AC. Treatment of Aggression in Patients With Bipolar Disorder. J Clin Psychiatry. 1999;60Suppl 15:25–28.10418811
- Wilson WH, Claussen AM. 18-month outcome of clozapine treatment for 100 patients in a state psychiatric hospital. Psychiatr Serv. 1995;46(4):386–389. doi:10.1176/ps.46.4.386 [CrossRef]7788462
- Ratey JJ, Leveroni C, Kilmer D, Gutheil C, Swartz B. The effects of clozapine on severely aggressive psychiatric inpatients in a state hospital. J Clin Psychiatry. 1993;54(6):219–23.8331090
- Barratt ES, Stanford MS, Felthous AR, Kent TA. The effects of phenytoin on impulsive and premeditated aggression: A controlled study. J Clin Psychopharmacol. 1997;17(5): 341–349. doi:10.1097/00004714-199710000-00002 [CrossRef]9315984
- Becker ME, Vakil E. Behavioural psychotherapy of the frontal-lobe-injured patient in an outpatient setting. Brain Inj. 1993;7(6):515–23. doi:10.3109/02699059309008179 [CrossRef]8260955
- Grigsby J, Kravcisin N, Ayarbe SD, Busenbark D. Prediction of deficits in behavioral self-regulation among persons with multiple sclerosis. Arch Phys Med Rehabil. 1993;74(12):1350–1353. doi:10.1016/0003-9993(93)90091-N [CrossRef]8259904