Evaluating persecutory delusions

Research examining the contribution of delusions to violent behavior provides mixed results. Earlier studies suggested that persecutory delusions were associated with an increased risk of aggression [4]. Delusions noted to increase the risk of violence were those characterized by threat/control-override (TCO) symptoms. TCO-type delusions are characterized by the presence of beliefs that one is being threatened (e.g., being followed or poisoned) or that one is losing control (i.e., control-override) to an external source (e.g., one’s mind is dominated by forces beyond the person’s control) [5]. Similarly, Swanson et al. [6], using data from the Epidemiologic Catchment Area surveys, found that people who reported threat/control-override symptoms were about twice as likely to engage in assaultive behavior as those with other psychotic symptoms.

In contrast, results from the MacArthur Study of Mental Disorder and Violence showed that the presence of delusions did not predict higher rates of violence among recently discharged psychiatric patients [7]. In particular, a relationship between the presence of TCO delusions and violent behavior was not found. A subsequent analysis of the data indicated that men were significantly more likely than women to engage in violence during times they experience threat delusions, whereas women were significantly less likely to engage in violence due to threat delusions [8].

In a study that compared male criminal offenders with schizophrenia who had been found not guilty by reason of insanity to matched controls of non-offending schizophrenic persons, Stompe et al. [9] also found that TCO symptoms showed no significant association with the severity of violent behavior, nor did the prevalence of TCO symptoms differ between the two groups. However, nondelusional suspiciousness, such as misperceiving others’ behavior as indicating hostile intent, has demonstrated an association with subsequent violence [7].

Nederlof et al. [10] conducted a cross-sectional, multi-center study to further examine whether the experience of TCO symptoms is related to aggressive behavior. The study sample included 124 psychotic patients characterized by the following diagnostic categories: 70.2% paranoid schizophrenia, 16.1% “other forms” of schizophrenia, 3.2% schizoaffective disorder, 0.8% delusional disorder, and 9.7% psychosis not otherwise specified (NOS). The authors determined that TCO symptoms were a significant correlate of aggression in their study sample. When the two domains of TCO symptoms were evaluated separately, only threat symptoms made a significant contribution to aggressive behavior. In their attempt to reconcile conflicting findings from earlier research regarding the relationship of TCO symptoms to aggressive behavior, the authors suggested that various methods of measuring TCO symptoms may underlie the seemingly contradictory findings among various studies [10].

In addition to research examining the potential relationship of particular delusional content to aggression, Appelbaum et al. [11] utilized the MacArthur–Maudsley Delusions Assessment Schedule to examine the contribution of noncontent-related delusional material to violence. These authors found that individuals with persecutory delusions had significantly higher scores on the dimensions of “action” and “negative affect,” indicating that persons with persecutory delusions may be more likely to react in response to the dysphoric aspects of their symptoms [10]. Subsequent research has demonstrated that individuals who suffer from persecutory delusions and negative affect are more likely to act on their delusions [4,12,13]. Coid et al. [14] found that anger due to delusions is a key factor that explains the relationship between violence and acute psychosis. Angry affect, in particular, has been shown to be an important intermediate variable in the pathway between anger delusions. When translating the various research findings into a practical examination, the psychiatrist should consider asking about five specific delusions that may increase the risk of violence, particularly when the patient presents as angry [15]. These delusions are listed in Table 5.2.

Evaluating auditory hallucinations

A careful inquiry about hallucinations is required to determine whether their presence increases the person’s risk to commit a violent act. Command hallucinations are those that provide some type of directive to the patient. Command hallucinations are experienced by approximately half of hallucinating psychiatric patients [16]. The majority of command hallucinations are nonviolent in nature, and patients are more likely to obey nonviolent instructions than violent commands [17].

The research on factors that are associated with a person acting on harmful command hallucinations has been mixed. In a review of seven controlled studies examining the relationship between command hallucinations and violence, no study demonstrated a positive relationship between command hallucinations and violence, and one found an inverse relationship [18]. In contrast, McNiel et al. [19] reported that, in a study of 103 civil psychiatric inpatients, 33% reported having had command hallucinations to harm others during the prior year, and 22% of the patients reported that they complied with such commands. The authors concluded that patients in their study who experienced command hallucinations to harm others were more than twice as likely to be violent [19].

Much of the literature examining the relationship of a person’s actions to command hallucinations has examined the person’s response to all command hallucinations, without delineating factors specific to violent commands. Seven factors associated with acting due to command hallucinations include the following [16].

Factors associated with acting on general command hallucinations as described above have also been found to indicate increased compliance with acting on violent command hallucinations [21,23]. Studies that have examined compliance specific to harmful command hallucinations provide additional guidance when evaluating the person’s potential risk of harm. Some aspects relevant to increased compliance to violent command hallucinations include the following.

Schizophrenia and violence risk

Although the majority of individuals with schizophrenia do not behave violently [26], there is emerging evidence that a diagnosis of schizophrenia is associated with an increase in criminal offending. In a retrospective review of 2861 Australian patients with schizophrenia followed over a 25-year period, Wallace et al. [27] found that patients with schizophrenia accumulated a greater total number of criminal convictions relative to matched comparison subjects. These authors noted that the criminal behaviors committed by schizophrenic patients could not be entirely accounted for by comorbid substance use, active symptoms, or characteristics of systems of care [27]. Likewise, Short et al. [28] found that even schizophrenic patients without comorbid substance-use disorders were significantly more likely than controls to have been found guilty of violent offenses.

Depression and Violence Risk

Depression may result in violent behavior, particularly in depressed individuals who strike out against others in despair. After committing a violent act, the depressed person may attempt suicide. Depression is the most common diagnosis in murder–suicides [30]. Studies that have examined mothers who kill their children (filicide) have found that they were often suffering from severe depression. High rates of suicide following a filicide have been noted, with between 16%–29% of mothers and 40%–60% of fathers taking their life after murdering their child [30–32]. In a study of 30 family filicide–suicide files, the most common motive involved an attempt by the perpetrator to relieve real or imagined suffering of the child – a motive known as an altruistic filicide. Eighty percent of the parents in this study had evidence of a past or current psychiatric history, with nearly 60% suffering from depression, 27% with psychosis, and 20% experiencing delusional beliefs [31].

In their analysis of 386 individuals from the MacArthur Violence Risk Assessment Study with a categorical diagnosis of depression, Yang et al. [33] noted two important findings relevant to depression and future violence risk. First, violence that had occurred within the past 10 weeks was a strong predictor of future violence by participants with depression, but not by participants with a psychotic disorder. This finding suggests that a past history of recent violence may represent a higher risk of future violence in depressed patients than in those with psychosis. Second, this risk of future harm by depressed patients was further increased with alcohol use.