Psychiatric Symptoms Do Not Precede Criminal Behavior for the Majority of Mentally Ill Offenders

lhbPsychiatric symptoms do not precede criminal behavior for the majority of mentally ill offenders. This is the bottom line of a recently published article in Law and Human Behavior. Below is a summary of the research and findings as well as a translation of this research into practice.

Law and Human Behavior 2014, Vol. 38, No. 5, 439-449

How often and How Consistently do Symptoms Directly Precede Criminal Behavior Among Offenders with Mental Illness?


Jillian K. Peterson University of California, Irvine
Patrick Kennealy University of South Florida
Jennifer Skeem University of California, Irvine
Beth Bray University of North Dakota
Andrea Zvonkovic Columbia University


Although offenders with mental illness are overrepresented in the criminal justice system, psychiatric symptoms relate weakly to criminal behavior at the group level. In this study of 143 offenders with mental illness, we use data from intensive interviews and record reviews to examine how often and how consistently symptoms lead directly to criminal behavior. First, crimes rarely were directly motivated by symptoms, particularly when the definition of symptoms excluded externalizing features that are not unique to Axis I illness. Specifically, of the 429 crimes coded, 4% related directly to psychosis, 3% related directly to depression, and 10% related directly to bipolar disorder (including impulsivity). Second, within offenders, crimes varied in the degree to which they were directly motivated by symptoms. These findings suggest that programs will be most effective in reducing recidivism if they expand beyond psychiatric symptoms to address strong variable risk factors for crime like antisocial traits.


offenders, mental illness, mental health symptoms, crime, recidivism

Summary of the Research

Approximately 1 million people in the criminal justice system have a major mental disorder such as schizophrenia, bipolar disorder, or major depressive disorder. This constitutes about 14-16% of the 7.3 million people who are under correctional supervision. A direct link between criminal behavior and psychiatric symptoms is the assumption of most policy initiatives, and the majority of research has focused on the role of these symptoms in causing crime.

Identifying how often offenders commit crimes that are motivated by symptoms of mental illness will vary based on how symptoms of mental illness are defined. Including only hallucinations and delusions provides a narrower definition than including more normative traits encompassing anger, impulsivity, irritability or aggression and will result in a lower estimate of mental health symptoms motivating criminal behavior.

As the definition of symptoms of mental illness broadens beyond psychosis, it becomes increasingly difficult to distinguish between symptoms and normative risk factors for crimes. For example, anger is correlated with symptoms of psychosis (delusions and command hallucinations), personality disorders (emotional instability), mood disorders (irritability and “anger attacks”), and post-traumatic stress disorder; however, anger is also a fundamental and functional human emotion that is a robust dynamic risk factor for violence among both general offenders and psychiatric inpatients. It is difficult to distinguish between anger as a human emotion and anger as a symptom of mental illness. To make this distinction, anger must be examined in relation to an individual’s typical behavior. This difficulty in distinguishing between symptoms and normative traits also remains true for impulsivity.

This research examined the relation of symptoms of mental illness and criminal behavior in a sample of 143 offenders with major depression, bipolar disorder, or schizophrenia spectrum disorders. Participants completed a 2-hour interview that focused on past criminal behavior, mental health symptoms, and the connection between the two. Among these 143 offenders, a total of 429 crimes were coded with respect to the degree to which they were directly a result of symptoms of mental illness.

Question 1: How Often Do Offenders Commit Crimes Motivated by Mental Health Symptoms?

The first aim of this study was to examine how often psychiatric symptoms are related to criminal behavior. Symptoms of psychotic disorder, bipolar disorder, and depression were considered and analyzed with respect to whether the symptoms immediately preceded the crime and increased its likelihood of occurrence.

Proportion of direct crimes by diagnosis

Of the 429 crimes coded, almost two thirds (64.7%) were coded as completely independent and less than one in 10 (7.5%) were coded as completely direct. About one third (27.9%) of crimes fell in the middle of the continuum, indicating mixed or moderate symptom involvement.

Schizophrenia spectrum distribution

Of crimes committed by participants with schizophrenia spectrum disorders, 23% were completely or mostly related directly to symptoms. Of crimes related to schizophrenia spectrum disorders, 42% were crimes against another person, 42% were property crimes, and 16% were minor crimes such as trespassing.

Bipolar disorder

Of crimes committed by participants with bipolar disorder, 62% were completely or mostly related directly to symptoms. Of crimes related to symptoms of bipolar disorder, 39% were crimes against another person, 42% were property crimes, and 19% were minor crimes.


Some 15% of crimes committed by participants with depression were completely or mostly related directly to symptoms. Of crimes related to symptoms of depression, 39% were crimes against another person, 15% were property crimes, and 46% were minor crimes” (p. 444).

Question 2: How Consistently Are Symptoms of Mental Illness Linked to Criminal Behavior Over Time, Across Incidents?

Additionally, this study examined whether the relationship between symptoms and crime is consistent with the offender’s criminal history. That is, the extent of consistency between symptoms and crimes was examined to determine whether there is a subgroup of mentally ill offenders that consistently commit crimes in response to their symptoms.

“The 18% of crimes coded as mostly or completely related directly to symptoms were scattered among 38% of offenders. Of the 38% of offenders with at least one direct crimes, most (66.7%) also committed at least one crime that was coded ‘mostly or completely’ independent. This suggests that the relationship between symptoms and criminal behavior varies over time within an offender” (p. 445).

The “results indicate that little or no variance in direct continuum scores can be attributed to offenders—that crimes are inconsistently related to symptoms within a given offender, over time. The majority of offenders who committed a “mostly or completely” direct crime committed at least one crime independent of symptoms as well” (pp. 445-446).

Translating Research into Practice

These “findings question the accuracy of past distinctions between offenders with mental illness whose criminal behavior is or is not directly caused by symptoms. These findings also underscore the fact that symptoms other than psychosis can lead directly to criminal behavior. As noted earlier, however, distinguishing between symptoms that are specific to major mental disorder and features that may be found among offenders without mental illness can be difficult. Further investigation of specific symptoms of Axis I disorders in causing crime is needed.

[These] findings also question the current policy focus on controlling symptoms as a means toward recidivism reduction. As shown in prior literature reviews, system solutions like diversion programs that focus predominantly on symptom control tend to have little effect on recidivism. The findings in this study indicate that effective mental health treatment may prevent a minority of crimes from occurring (about 18%, according to our findings), but would likely not improve criminal justice outcomes for the vast majority of offenders with mental illness. In keeping with past, [these] results suggest that psychiatric symptoms are not robust, independent risk factors for criminal recidivism.

Instead, most offenders with mental illness—whether they occasionally commit a crime that is directly motivated by symptoms or not—may benefit from interventions that reduce recidivism for offenders without mental illness. For example, cognitive– behavioral treatment focused on criminal cognition or services that target variable risk factors for high-risk offenders have been shown to reduce criminal recidivism for general offenders. Developing a better understanding of causal factors for recidivism among offenders with mental illness can inform better correctional interventions, both in institutions and probation and parole” (p. 447).

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Special Contributor

BeltraniAmandaContributions to this post were made by Amanda Beltrani.

Amanda M. Beltrani is a first-year graduate student in the Forensic Psychology masters program at John Jay College of Criminal Justice in New York. Her professional interests include forensic assessments and criminal matter evaluations. Amanda plans to continue her studies in a doctoral program after completion of her Masters degree.

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