Consistent with the results of prior epidemiologic research,3–7
violent behavior before and since age 15 was significantly increased among individuals with alcohol and drug use disorders. Bipolar I and II disorders were associated with increased risks of violent behavior both before and since age 15, and MDD was associated with an increased risk of violent behavior since age 15. These new findings reflect the fact that the NESARC was the first epidemiologic study to differentiate between MDD and bipolar disorders, while at the same time controlling for sociodemographic characteristics and comorbidity. In contrast to previous studies,3,6,7
that examined aggregate measures of any anxiety disorder, this study also found increased risks of violent behavior since age 15 among individuals with panic disorder without agoraphobia and with specific phobia.
Information on the associations of PDs other than antisocial PD, nicotine dependence, and pathological gambling with violent behavior has not previously been available. This study found increased odds of violent behavior both before and since age 15 among individuals with paranoid, schizoid, histrionic, and obsessive-compulsive PDs, as well as nicotine dependence, with increased odds observed among individuals with pathological gambling for violent behavior since age 15. Within the context of these findings, it is important to note that the clear majority of individuals with psychiatric disorders do not engage in violent behavior, a finding that we will elaborate upon later.
had suggested that the observed associations between psychiatric disorders and violent behavior could be explained in terms of underlying sociodemographic factors, but this study, which controlled for sex, age, and race-ethnicity, has not supported this view. Psychiatric disorder appears to be an independent correlate of violent behavior, albeit a modest one (ORs=1.29–3.72), for individual disorders. It was not surprising that individuals with substance use disorders, who have earlier ages at onset than other Axis I disorders16, 17
were more likely to engage in violent behavior both before and after age 15. The violent behavior of these individuals is most likely due to the disinhibiting effects of alcohol and drugs. In addition, individuals with drug use disorders are of necessity exposed to illegal drug markets that promote violence.46
Interestingly, pathological gambling, an impulse control disorder closely related to substance use disorders, was also associated with an increased odds of violent behavior since age 15. Individuals with pathological gambling may also share with individuals who have substance use disorders exposure an illegal market, in this case to the illegal betting enterprise, an industry often inextricably linked to the illicit drug market. By contrast, nicotine dependence appears to contribute to the public health burden of violence largely through its comorbidity with other substance use disorders. This explanation is partially supported by the observation that relatively few individuals in the general population with pure nicotine dependence engaged in violent behavior (n=173,903) compared to those with comorbid nicotine dependence (4,850,249).
Increased rates of violent behavior were also observed among individuals with MDD, bipolar I and II disorders, panic disorder with agoraphobia, specific phobia, and paranoid, schizoid, histrionic, and obsessive-compulsive PDs. Paranoid PD, characterized by a pervasive distrust and suspiciousness of others, may predispose toward violence through a number of avenues including pathological jealousy, the tendency to bear persistent grudges, and misinterpretation of even benign remarks or events as threatening. The tendency of individuals with paranoid PD to react to even minor stimuli with anger is also seen among those with histrionic PD, a predisposition that may increase the likelihood of violent behavior. The salient features of schizoid PD, i.e., aloofness, lack of close friends or confidants, and emotional coldness, could contribute to violent behavior among affected individuals by virtue of their extreme detachment from ordinary feelings and emotions. As with schizoid PD, individuals with obsessive-compulsive PD can be characterized by apparent formality and social detachment, both of which can increase the probability of violent behavior.
Possible symptomatology and related motivations underlying the relationships of mood and anxiety disorders with violent behavior are less clear. Major depressive disorder and bipolar disorders characterized predominantly by irritability or hyperirritability may contribute to the occurrence of violent behaviors among individuals with these presentations. Panic attacks associated with panic disorder without agoraphobia and often accompanying specific phobia may lead to weakening of self-control mechanisms, increasing the likelihood of violent behavior among affected individuals, similar to the override of personal controls shown to predispose toward violence among psychotic individuals experiencing certain types of hallucinations and delusions.47–49
Future attempts to specify which symptoms of specific psychopathology are associated with violent behavior, together with tests of theory-driven explanations about the mechanisms that produce such associations, are sorely needed. Future research examining patterns of violence should recognize that violence among individuals with psychiatric disorders cannot be explained solely in terms of the clinical features of the disorders. The impact of symptomatology on violent behavior can only be adequately understood in the context of social relationships, that is, the ways in which symptomatology affects relationships by impairing individuals’ abilities to relate meaningfully to others, gain critical social support, and resolve conflicts.50
Although the aforementioned results provide information on which specific psychiatric disorders are associated with rates of violent behavior in excess of the control group without any lifetime DSM-IV disorder, the data do not address the magnitude of the problem because they ignore the base rates or prevalences of specific psychiatric disorders in the general population. When base rates and associated population estimates of violent behavior since age 15 were estimated for each pure disorder, the number of individuals who engaged in violent behavior, with pure substance use disorders (n=1,150,363), especially alcohol abuse (n=479,067) was clearly greater than the combined number of individuals who engaged in violent behavior with pure mood (n=149,156), anxiety (n=84,521), and PDs (n=80,815).
Although previous research has established that comorbidity with substance use disorders increases the risk of violent behavior among individuals with other psychiatric disorders,3–7,47
this study was the first to show that comorbidity between and within Axis I and II disorders also significantly increases the likelihood of violent behavior regardless of which specific psychiatric disorder was examined. Indeed, the public burden of violence since age 15 was 1,507,970 among individuals with specific lifetime pure psychiatric disorders, whereas the corresponding burden among those with comorbid disorders was 7,719,156. The increased disability and impairment in social and occupational functioning among comorbid individuals, well documented in both the clinical and the epidemiologic literatures,16
may predispose toward violence in these individuals. Future research examining associations between disability and violent behavior among individuals with pure and comorbid psychiatric disorders appears warranted.
When interpreting the results of this study, it is important to keep in mind, as previously mentioned, that only a minority of individuals with psychiatric disorders (i.e., 9,227,126 of 110,365,733) engage in violent behavior, a result that does not validate the public image of all individuals with psychiatric disorders as potentially violent. The public health burden of violent behavior, however, is clearly greater among individuals with psychiatric disorders (n=9,227,126) than among individuals with no psychiatric disorders (n=641,718) in the general population when expressed in terms of U.S. population estimates. In marked contrast to findings of previous research,3–7, 51
psychiatric disorders were found in this study to be associated with violent behavior in the general population. Prior research focused exclusively on the modest to moderate increases in rates of violent behavior among individuals with psychiatric disorders, which this study also found, while ignoring the burden of violent behavior attributable to individuals with psychiatric disorders, by not analyzing base rates and population estimates. Previous research5, 51
also failed to present the burden of violent behavior attributable to those without psychiatric disorders and to compare these estimates with those associated with any psychiatric disorder. Further, conclusions from past research that only a weak association exists between psychiatric disorder and violent behavior, based on analyses showing that demographic factors were far better predictors of violent behavior than psychiatric disorders, were also not supported by the results of this study. Significant associations remained between specific psychiatric disorders and violent behavior even after controlling for sociodemographic factors and comorbidity.
This study has increased our understanding of the relationship between psychiatric disorders and violent behavior by demonstrating that the burden of violent behavior in the general population is not equally shared across the spectrum of psychiatric disorders. Burden is limited to several particular disorders, most noteworthy alcohol and drug use disorders followed in magnitude by nicotine dependence, personality disorders and mood disorders, with anxiety disorders and pathological gambling contributing little to the overall burden of violent behavior. In fact, individuals with alcohol and drug use disorders contribute more to the public health burden of violent behavior than all other psychiatric disorders combined. Reducing levels of anger leading to violent behavior is now seen as an important component in substance use treatment and anger dyscontrol has been associated with relapse.52
Although anger management modules and emotional regulation are often components of substance use treatment programs there exist no large scale randomized controlled clinical trials of such programs.53, 54
Clearly, the need to develop, evaluate and implement anger management programs and their ability to control the consequences of anger as both an affect and behavior is needed to break the alcohol and drug use disorder-violent behavior cycle.
Individuals with alcohol and drug use disorders have also repeatedly been identified as high risk groups for intimate partner violence (IPV).55–57
However, not much is currently known about the best treatments for IPV among individuals with alcohol and drug use disorders and the efficacy of domestic violence intervention programs tailored to these individuals is unknown.58
Comprehensive evaluation of IVP among married or cohabiting individuals entering substance abuse treatment, strengthening referral linkages between these programs, and developing and evaluating interventions for IVP that can be integrated into substance abuse treatment programs can help substantially reduce the public health burden of violent behavior. Increasing prevention efforts aimed at excessive alcohol and/or drug use, especially among high risk subgroups of the population, will also be needed to parallel treatment interventions if the burden of violent behavior attributable to these disorder is to be reduced.
Similar to all previous epidemiologic work in this area, the present study was cross-sectional, whereas several questions regarding relationships between violent behavior and psychiatric disorders would best be examined in a longitudinal design. Although this study has advanced our understanding of the relationship between violent behavior and psychiatric disorders, prospective epidemiological studies of general populations will be needed to determine the exact nature of that relationship. The Wave 2 NESARC, a three-year follow-up of participants in this Wave 1 survey, was designed to address this limitation. Further, general population surveys may not capture all individuals who engage in violent behaviors, since these individuals are more likely to be incarcerated, homeless or otherwise less likely to live in households, the exclusive sampling frame of most general population surveys. However, the NESARC sampled from households and group quarters (e.g., shelters, halfway houses, group homes), one strategy designed to increase representation in the sample of individuals who engage in violent behavior. Based on these considerations of potential underrepresentation of individuals who engage in violent behaviors, NESARC estimates of prevalences and risks are likely to be conservative.
Stigma of mental disorders and substance use disorders, and the public perceptions and anxieties associated with stereotypes of violence among individuals with these disorders, appear to be largely unwarranted, as the majority of individuals with these disorders do not engage in violent behavior. However, the public health burden of violence in the general population appears to be most attributable to individuals with psychiatric disorders, with specific disorders disproportionately contributing to that burden. Clearly the public health burden of violent behavior can be largely attributed to alcohol and drug use disorders. With regard to public health implications, campaigns to educate the public about the low prevalence of violent behavior among individuals with psychiatric disorders and those disorders most associated with violence appear warranted. With regard to clinical implications, there is a need to assess violent behavior particularly among comorbid individuals, especially those with specific psychiatric disorders most significantly related to violence in this study. Future research on the interplay of various factors affecting the relationships found in this study can refine the identification of subgroups of individuals with psychiatric disorders who are particularly prone to violent behavior. Increasing our knowledge of the circumstances under which violence among individuals with specific psychiatric disorders is likely to occur promises to improve the accuracy of prediction in clinical practice; this in turn will contribute to the development of more effective prevention strategies in the future.