Part I: Mental Illness, Firearms, And Violence

Report Civil Society

Part I: Mental Illness, Firearms, And Violence

January 31, 2019 Over an hour read Download Report

Authors: John Malcolm and Amy Swearer


This is Part I of a three-part series of papers examining the intersection of mental illness, violence, and firearms. As the nation sits in the midst of a serious discussion about gun violence in general, and mass shootings in particular, we must ensure that policy decisions regarding Second Amendment rights reflect an accurate understanding of the role mental illness does and does not play in gun violence, as well as an accurate understanding of why the United States is suffering from a crisis of untreated serious mental illness.

Key Takeaways

Policies aimed at protecting the public from mass public shootings must not overlook the role of firearm access by individuals with serious mental illness.

Such policies must also take, however, a holistic approach that accounts for the various factors known to impact rates of firearm-related violence.

They must also do so without infringing on the constitutional rights of those who are not at risk of violent behavior.

In order to understand the relationship between mental illness, violence, and firearms, we must first understand the complex phenomenon of “mental illness.” Although many Americans will experience some degree of mental illness at least once in their lives, only a small percentage will develop serious, chronic mental illnesses that substantially impact their ability to function on a daily basis.

“Mental illness” is a complex topic that affects millions of Americans every year.

The most common interaction of mental illness and firearm-related violence is suicide, which accounts for two-thirds of all annual gun-related deaths. While the United States has a comparatively high percentage of suicides that are committed with firearms as opposed to other means, it does not have a particularly high overall suicide rate compared to countries that severely limit civilian access to firearms. It is clear that mental illness plays a key role in suicide, whether carried out with firearms or through other means, but policies seeking to reduce the overall suicide rate should account for the many factors associated with increased risks of suicide, not just the presence of mental illness. Similarly, broad limitations on firearm access for individuals who are not necessarily at a heightened risk for committing suicide are unlikely to meaningfully impact overall suicide rates and should be viewed with a heavy dose of skepticism.

 Finally, while most mentally ill individuals are not—and never will become—violent, certain types of untreated, serious mental illness are associated with a higher prevalence of interpersonal violent behaviors. In particular, untreated serious mental illness is prevalent in a substantial majority of individuals who commit mass public shootings. As with suicides, this does not suggest that mass killings by individuals with serious mental illness are likely to be reduced by broadly limiting civilian access to firearms. The connection between untreated serious mental illness and specific types of firearm-related violence cannot, however, be overlooked, and must be addressed as one of many factors in a truly holistic approach to understanding the interaction between mental illness and violence.

I. What Is Mental Illness?

In order to understand the role mental illness plays in violence generally, and in firearm-related violence specifically, we must first answer one important question: What is mental illness? This is no easy task, as mental illness is an extraordinarily complex phenomenon. “Mental illness” refers to a medical condition that causes significant behavioral or psychological symptoms that impair a person’s ability to think, feel, and relate to others,REF which often causes “a diminished capacity for coping with the ordinary demands of life.”REF The term “mental illness” is used interchangeably with “mental disorder,” which the American Psychiatric Association defines as “a syndrome characterized by clinically significant disturbance in an individual’s cognition, emotional regulation, or behavior that reflects a dysfunction in the psychological, biological, or developmental processes underlying mental functioning.”REF Put more simply, mental illness is a medical condition that primarily affects a person’s thought processes and emotions instead of his or her physical abilities.

Just as there are many different types of physical illnesses, there are many different types of mental illnesses. It is a broad definition that can include a number of subset mental illness “groupings,” like affective disorders,REF personality disorders,REF anxiety disorders,REF and psychotic disorders.REF It covers such varied diagnoses as schizophrenia,REF depression,REF bipolar disorder,REF post-traumatic stress disorder (PTSD),REF and agoraphobia.REF

As with physical illness, the symptoms of mental illness can range from mild, temporary, and manageable to severe, life-long, and debilitating.REF And, similar to physical illnesses, mental illness is a very common occurrence, with anywhere from one-third to one-half of Americans experiencing mental illness at some point in their lives.REF Many of these individuals, however, will never present a danger to themselves or others, nor even find themselves significantly or chronically impaired.REF In other words, only a small subset of individuals with mental illness will suffer from “serious mental illness,” which is generally defined as a “functional impairment which substantially interferes with or limits one or more major life activities.”REF While any subset of mental illness can rise to the level of “serious mental illness,” individuals with schizophrenia, bi-polar disorder, and major depression comprise the bulk of those suffering from serious mental illness.REF Fewer than 1 in 25 individuals in the United States will develop one of these serious mental illnesses.REF

The breadth and complexity of mental illness present a major challenge to simplistic conceptions of mental illness and its relationship to violence. Proper care must be taken to distinguish among different types of mental illness, the circumstances under which some mentally ill individuals may become violent, and the policies that will prove most helpful to addressing this limited subset of seriously mentally ill individuals. It is important that all persons—whether medical professionals, policymakers, law enforcement, or just concerned citizens—refrain from categorizing and treating mentally ill persons as a group instead of as individuals with varied and complex histories, problems, and outlooks. That having been said, while there are still many unanswered questions regarding the role mental illness plays in violence trends, what is clear is that untreated serious mental illness does, indeed, play a significant role.

II. Mental Illness, Firearm Access, and Suicide

Most gun deaths in the U.S. are suicides, but there is little statistical connection between overall suicide rates, gun laws, and general firearm access.

By far, the most significant intersection of mental illness and violence—especially violence committed with firearms—is that of suicide. Almost two-thirds of annual firearm-related deaths in the United States are suicides, an average of about 21,000 suicides by firearm every year.REF Of course, not every suicide is necessarily related to an underlying mental illness,REF but there can be little doubt that the presence of mental health disorders—particularly affective disorders such as PTSD and depression—contribute substantially to the suicide rate.REF The most commonly employed means of committing suicide in the United States is the use of a firearm, an unsurprising reality given that the United States has the highest number of privately owned firearms per capita in the world.REF Although some specific gun control policies may be effective at reducing the number of suicides committed with firearms, there is no evidence that these policies reduce the overall risk of suicide in the general population.REF

While there are still many unanswered questions regarding the role mental illness plays in violence trends, what is clear is that untreated serious mental illness plays a significant role.

Any suicide is tragic, regardless of the means used, and more can certainly be done to study why some people choose to end their own lives, including suicides committed by those with mental health issues.REF But the reality is that the United States, even with its relatively high rate of firearm suicides, does not have a particularly high overall suicide rate compared to other developed countries.REF In fact, our national suicide rate stands roughly at the world average and is comparable to the rate experienced by many European countries—despite their significantly lower rates of private firearm ownership.REF At the same time, a number of countries with severely restrictive gun control laws have significantly higher rates of suicideREF than the United States, including France,REF Finland,REF Belgium,REF Russia,REF Japan,REF and South Korea.REF

Suicide rates in the United States have remained relatively stable over the past 50 years,REF even though the number of guns per capita has doubled.REF Moreover, since 1999, while the number of privately owned firearms has increased by more than 100 million, the percentage of suicides committed with firearms has actually decreased.REF Further, some states with permissive gun laws (like Texas and Nebraska)REF and with some of the highest numbers of guns per capita (like Mississippi and Hawaii)REF have comparatively low rates of suicide,REF while other states with relatively restrictive gun laws (like Colorado and Washington)REF and low rates of firearm ownership (like New Hampshire and Maine)REF have comparatively high rates of suicide.REF

As this data suggests, there are other socioeconomic factors beyond firearm possession rates that appear to account for differences in suicide rates. Several studies, for example, suggest that divorce rates are strongly linked to suicide rates.REF Other studies have found strong relationships between suicides rates and other measures of social cohesion, such as unemployment, poverty, past trauma, resource shortages, family structure, immigration and cultural assimilation, and the size of one’s social group.REF It is apparent that, regardless of which measure of social cohesion is used, more socially integrated societies tend to have lower suicide rates.REF Analyses of the relationship between firearm ownership rates and suicide rates regularly fail to account for these and other important factors that likely affect both firearm ownership rates and suicide rates.

When individuals have serious mental illness, firearm access may increase their risk of committing suicide.

As evidenced above, it is unlikely that general rates of gun ownership meaningfully affect overall suicide rates at a state or national level. That does not necessarily mean, however, that specific individuals are not at a greater risk of committing suicide if they have access to a firearm. Individuals with serious mental illness are at a substantially greater risk of committing suicide than are individuals without serious mental illness, irrespective of the means used.REF And studies indicate that when individuals with serious mental illness have access to firearms, it further increases their individual risk of committing suicide.REF

But the reality of firearm access, mental illness, and suicide may also be a bit more complicated. One recent study analyzed the use of firearms to commit suicide by those with a mental illness or substance-abuse disorder compared to the use of firearms in suicides by those without a known history of mental illness or substance-abuse disorder.REF It found that serious mental illness was associated with increased odds of committing suicide generally, but also that individuals with serious mental illness who committed suicide were less likely to use firearms than were individuals without serious mental illness who committed suicide.REF In other words, while individuals with serious mental illness may have an increased risk for committing suicide when they have ready access to firearms, they may also be generally less likely to commit suicide with firearms.

Since 1999, while the number of privately owned firearms has increased by more than 100 million, the percentage of suicides committed with firearms has actually decreased.

What might account for these apparent discrepancies? One of the reasons that individuals with serious mental illness may be less likely to commit suicide with a firearm is that they often have greater barriers to firearm access. For example, state and federal laws prohibit the purchase and possession of firearms by many individuals with serious mental illness,REF and such individuals are also more likely to have friends or family members who monitor or limit their unsupervised access to firearms.REF And yet despite the common limitations on firearm access imposed on individuals with serious mental illness, the study still found that roughly 40 percent of individuals with a known history of mental illness who committed suicide did so with a firearm.REF This suggests that the studies are not at odds with each other at all: It is precisely because firearm access increases the risk of suicide for those with mental illness that we have taken steps to reduce firearm access for these individuals, and this in turn appears to have lowered the use of firearms by those individuals to commit suicide—even if it has not prevented many others from committing suicide via other means.

Finally, the fact that significant numbers of suicides by both those with and without serious mental illness are carried out by means other than firearms indicates that the risk of suicide is far from limited to individuals with serious mental illness who also have access to firearms. Several studies suggest that reducing unsupervised access to commonly employed means of suicide (such as firearms, sharp objects, medications, and rope material) would likely reduce suicide rates for certain at-risk persons, regardless of whether they have serious mental illness.REF In sum, policies designed to reduce suicide rates by limiting firearm access for mentally ill persons may be an important step in the right direction for reducing state and national suicide rates, but they are not comprehensive solutions to a much more complex problem.REF

III. Mental Illness, Firearms, and Interpersonal Violence

Untreated serious mental illness is associated with a higher likelihood of violent behavior.

There is no evidence to support a claim that all persons with mental illness constitute a “high-risk” population with respect to interpersonal violence in general and firearm-related interpersonal violence in particular. The vast majority of people suffering from mental illness will never become violent toward others, and are, in fact, much more likely to be the victims of violent crime.REF Most comprehensive studies estimate that mental illness is responsible for only 3 percent to 5 percent of all violent crimes committed in the United States, and an even smaller percentage of those crimes involve firearms.REF Moreover, some current research suggests that the relationship between psychiatric disorders and violence is minimal in the absence of substance abuse—though there is significant disagreement on this subject.REF Neither is there any evidence that people with serious mental illness who are receiving appropriate treatment are more dangerous than individuals in the general population.REF On the contrary, “most episodes of violence committed by mentally ill persons are associated with our failure to treat them.”REF

At the same time, a substantial body of research indicates that people who exhibit specific symptoms associated with serious mental illness are more likely to commit violent acts than the general population or other mentally ill people.REF One study regarding the relationship between serious mental illnesses—like bipolar disorder and schizophrenia—concluded that “[o]nce gender, age, socio-demographic and socio-economic status are taken into account, the overall risk for physical assault is generally estimated to be 3 to 5 times higher [for those with major mental illness] than that of the general population.”REF At least 20 different studies have found a positive relationship between psychotic delusions and violence, especially when those delusions involve paranoid beliefs about persecution and exaggerated perceptions of threat risks or involve “command hallucinations” in which voices inside their heads command them to commit violent acts.REF And while mental illness in general may have a limited relationship to violent crime in general, studies in both the United States and the international community routinely suggest that individuals with untreated schizophrenia and bipolar disorder are responsible for a disproportionate number of violent crimes,REF and for roughly 10 percent of murders in particular.REF Although it is estimated that only one in 300 persons with schizophrenia will kill someone, research suggests that individuals with schizophrenia commit homicide at a rate 20 times greater than that of the general population.REF

The risk of violent behavior is highest among individuals suffering from their first episode of psychosis,REF and among mentally ill individuals with histories of non-adherence to medication treatment regimen or discontinuation of treatment altogether.REF Unfortunately, as many as 50 percent of individuals with schizophrenia and bipolar disorder suffer from anosognosia—a lack of insight into the existence or severity of their illness—that is strongly associated with repeated refusals to take medication.REF A number of studies indicate that substance abuse greatly increases the likelihood of violent behavior within populations of mentally ill individuals, even when compared to the increased likelihood it also causes within the general population.REF

Notably, mentally ill individuals who exhibit violent behaviors become no more likely than the average population to commit acts of violence once they are adequately treated for their illness.REF This is consistent with analyses of mass killers with mental illness that have found that psychiatric treatment was either unavailable or underutilized in “virtually all cases of adult and adolescent mass murder.”REF At least one recent study reinforces the link between a lack of adequate treatment and an increased risk of violent behavior among severely mentally ill individuals, finding that higher homicide rates are associated with stricter civil commitment laws that make it harder to get someone involuntarily committed.REF This suggests that when states make it easier to mandate mental health treatment for individuals suffering from a mental illness who otherwise refuse or neglect it, it significantly decreases the likelihood that those individuals commit violent crimes in the future.

The relationship between mental illness and violence is further complicated by studies indicating that various socioeconomic factors can have significant mediating effects on whatever components of mental illness are associated with violence or crime.REF As one analysis of various studies concluded, it appears that “persons who suffer from serious mental illness, but who grew up in a healthy family environment (e.g., not violently victimized by family members), developed self-control and coping skills (no substance abuse), and who are able to maintain gainful employment (better able to afford living in a non-violent neighborhood) often seem to escape” any heightened risk of violence associated with mental illness.REF This appears to support assertions that the link between serious mental illness and violence is not clear-cut, even if it likely exists.

The majority of mass public killers exhibited clear signs of mental illness prior to their attacks, and some studies conclude that as many as two-thirds of all mass public killers suffered from a severe mental illness.

Finally, just because a person with a serious mental illness commits a violent act, it does not necessarily mean that the mental illness was the cause of the violent act.REF It appears that psychotic symptoms may be more likely to be a direct cause of homicidal behavior in schizophrenic individuals,REF but studies and the experiences of many in the law enforcement community also suggest that psychotic symptoms are not the immediate cause of most criminal acts committed by most mentally ill individuals.REF Even though we may not fully understand the complex mechanisms linking psychotic and delusional symptoms of mental illness to violence, the fact remains that there is a clear statistical link between them.REF

Many mass public killings—including mass public shootings—are committed by individuals with untreated mental illness.

Although most individuals suffering from a mental illness do not and will never pose a heightened risk of danger to the general public, there is a strong connection between mass public violence and mental illness that cannot be ignored. While acts of mass public violence are incredibly rare,REF they are often high-profile events that deeply impact the national view of violent crime trends; moreover, mass public shootings in particular stoke national conversations about gun violence and gun control.

Many mass public killings—including mass public shootings—are committed by individuals with untreated mental illness.

The majority of mass public killers exhibited clear signs of mental illness prior to their attacks, and some studies conclude that as many as two-thirds of all mass public killers suffered from a serious mental illness,REF although many of these individuals had not received an official diagnosis, much less treatment for a psychiatric condition.REF Consistent with research showing that personality disorders are the strain of mental illness most closely associated with violent tendencies, many high-profile mass public killers displayed obvious signs of paranoia, delusional thinking, and feelings of irrational oppression associated with schizophrenia or bipolar-related psychosis prior to their attacks.REF

Prominent examples of mass public killers exhibiting psychotic symptoms at the time of their attacks include:REF

  • Jiverly Wong killed 13 people and then himself at an America Civic Association center in Binghamton, New York, and sent a letter to a news station prior to the attack, detailing the inner workings of a mind completely removed from reality.REF Wong claimed he was being persecuted by undercover cops who caused him to lose his job by spreading rumors about him, touched him in his sleep, stole money from his wallet, and tried to force him into a car accident. Those close to Wong knew he was frustrated over losing his job and struggling with his English-language skills,REF but the letter reveals Wong likely suffered a psychotic break from reality at some point during the days and weeks leading up to the violence.REF
  • Jared Loughner killed six people, including Chief U.S. District Judge John Roll and nine-year-old Christina-Taylor Green, and wounded 13, including Rep. Gabrielle Giffords (D–AZ), in Tucson, Arizona.REF Loughner was almost certainly suffering from untreated schizophrenia in the year prior to the shooting.REF He exhibited such bizarre and concerning behavior that he was suspended from Pima Community College and told he could not return until he received a mental health evaluation “indicating his presence at the College does not present a danger to himself or others.”REF Loughner’s parents were so worried about his mental health that his father confiscated Loughner’s shotgun, disabled his car, and tried to get him mental health treatment.REF
  • Seung-Hui ChoREF and James HolmesREF—similar to Loughner—were both referred to their respective colleges’ mental health services due to concerns over their deteriorating mental states. Cho told his college roommate that he had a supermodel girlfriend who lived in outer space and traveled by spaceship, was known to fixate on female students, and had to be removed from his undergraduate poetry class over worrying behavior.REF After suggesting he might kill himself, he was determined to be “mentally ill and in need of hospitalization” for presenting a danger to himself or others, but received only minimal psychiatric treatment.REF Holmes was receiving psychiatric treatment from Student Mental Health Services at the University of Colorado prior to murdering 24 individuals at an Aurora, Colorado, movie theater.REF One of his psychiatrists was so concerned about Holmes’ mental state that she contacted University Police to discuss placing him under a psychiatric hold.REF
  • Jennifer San Marco’s psychological problems were so pronounced in the years before she shot and killed six post office workers that she was granted early retirement from her job in a mail sorting center and placed on medical disability.REF She was known to act erratically, including having rambling conversations with herself and taking off her shirt in public places.REF
  • Russell Weston killed two Capitol Police officers while under the delusion that the United States was on the verge of annihilation by a disease that turned people into cannibals.REF He told his court-appointed psychiatrist that he went to the Capitol to access “the ruby satellite,” the key to stopping the disease, which he believed was being kept in a Senate safe.REF

A significant number of mass public killers were not necessarily psychotic or delusional at the time of their attacks, but nonetheless exhibited increasingly troubled behavior strongly suggesting the presence of a severe mental disorder:

  • Adam Lanza, who killed 20 first-graders and six adults at the Sandy Hook Elementary School, began exhibiting symptoms consistent with schizophrenia, such as excessive hand washing and smelling non-existent aromas, in pre-school.REF Lanza regularly took special classes focusing on his speech and language deficiencies through elementary school and was diagnosed with Asperger’s Syndrome in the seventh grade.REF As an adolescent, he often refused to take medications or engage with behavioral therapists.REF He became increasingly antisocial in the year leading up to the shooting, closing himself in his room for long periods of time and communicating with his mother only through text messages, even though they lived in the same house.REF The final report from the State’s attorney noted that it was “well known that [Lanza] had significant mental health issues that affected his ability to live a normal life and interact with others,”REF but he did not appear to have lost touch with reality to a degree indicating psychosis.
  • Devin Kelley, who murdered 26 people at a Sutherland Springs, Texas, church in 2017, had a long history of non-psychotic mental illness. Kelley had been court martialed during his stint in the Air Force and confined to an on-base mental health facility for unspecified mental health disorders.REF He was deemed a danger to himself and others for attempting to sneak weapons onto base and threatening superior officers—and even attempted to escape the mental health facility. Kelley’s troubles continued after his 2012 bad-conduct discharge from the Air Force, which he received for serious domestic violence convictions. Two ex-girlfriends told reporters that Kelley stalked them after their respective break-ups, to the point where one of the women was forced to change her cell phone number several times.REF In 2014, Kelley was convicted of animal cruelty in Colorado, and police reports indicate that he “picked up the dog by the neck into the air and threw it onto the ground and then drug [the dog] away.”REF He was also investigated in Texas for allegations of sexual assault. While Kelley was not psychotic, he exhibited serious mental health red flags over a period of years indicating that he had paranoid and narcissistic tendencies that manifested themselves in violent ways.
  • Stephen Paddock, who committed the worst mass public shooting in U.S. history when he murdered 58 and wounded another 851 individuals attending a Las Vegas country music concert in 2017, was never diagnosed with a mental health disorder and maintained steady employment throughout his life.REF His primary care doctor, however, told police that he believed Paddock may have suffered from bipolar disorder, but Paddock had refused to discuss the subject.REF The few people close to Paddock described him as “standoff-ish,” “disconnected,” and “a man who had difficulty establishing and maintaining meaningful relationships.”REF He would often gamble at casinos for hours on end with minimal human contact, and some law enforcement officials have opined that Paddock likely suffered from some form of undiagnosed mental illness.REF
  • Elliot Rodger killed six and wounded 13 in a 2014 rampage near the University of California, Santa Barbara.REF He was seeing multiple mental health care professionals at the time of the killing, and had been attending similar therapy sessions intermittently since he was a child.REF Less than a month before the violent attacks, a staff member at a mental health agency requested that law enforcement conduct a welfare check on the attacker after being alerted to his social media posts about suicide and killing people.REF Sheriff’s deputies contacted the attacker at his apartment, but determined that his behavior did not meet the criteria for an involuntary psychiatric hold and did not conduct a search of his room, which would likely have revealed Rodger’s cache of firearms.REF
  • Then there is the case of Charles Whitman, who in 1966 created a “sniper’s perch” atop a campus bell tower at the University of Texas at Austin, killing 15REF and wounding 31 with his bolt-action hunting rifle.REF Whitman was a 25-year-old former Marine and Eagle Scout who received a scholarship from the Naval Enlisted Science Education Program to study architectural engineering.REF His emotional state soon took a turn for the worse, and he lost his scholarship after struggling with gambling and bad grades.REF Prior to the attack, he sought professional help for “overwhelming violent impulses”REF and left a note stating his wish that his brain be examined for “mental disorders” after his death.REF An autopsy revealed Whitman had a brain tumor that some have suggested could have affected his aggression levels and impulse-control capabilities.REF This would indicate that Whitman may have suffered from neurological changes unrelated to—but perhaps mimicking—serious mental illness.

Although many factors can combine in different ways to cause an individual to commit a violent act, when it comes to mass public shootings, it is increasingly clear that untreated mental illness is often a significant contributing factor. While such acts account for only a small percentage of all gun-related violent crime, they shake the national conscience and affect our feelings of general safety for understandable reasons.REF By focusing on intervention and treatment for individuals exhibiting clear signs of serious mental illness that heightens their risk of danger to self or others, we can lower the risk of mass public violence without imposing broad restrictions on the rights of law-abiding citizens.

Other Factors Unrelated to Serious Mental Illness That Play Prominent Roles in Acts of Mass Public Violence

While a strong association between untreated serious mental illness and acts of mass public violence exists, not all public mass killers have a history of identifiable symptoms of mental illness. Some mass public killers commit acts of violence due to a set of repugnant but otherwise rationally derived beliefs. Dylann Roof, who murdered nine individuals at a predominantly African American church in Charleston, held views of extreme racism and white supremacy.REF While his violent and extremist ideology is sickening, there are no indications that he exhibited delusional or psychotic symptoms that caused him to believe this ideology.

Similarly, Major Nidal Hassan, who killed 13 and wounded 32 during a violent attack at Fort Hood, Texas, may have been exceptionally angered by his perceived concerns over Muslim soldiers being deployed to fight other Muslims, and subscribed increasingly to radical jihadist beliefs. And Rizwan Farook and his wife Tasheen Malik were also motivated not by mental illness but by ideology when they murdered 14 and wounded 24 in San Bernardino, California, in 2015.REF Like Roof, however, Hassan, Farook, and Malik had no discernable history or signs of mental illness.REF

When it comes to mass public shootings, it is increasingly clear that untreated mental illness is often a significant contributing factor.

A number of mass killers could also reasonably be described as “irrationally disgruntled and full of rage” but may not have been suffering from a diagnosable mental disorder. For example, in 2010, Omar Thornton shot and killed eight co-workers at Hartford Distributors in Manchester, Connecticut, before committing suicide.REF On the day of the incident, Thornton had been forced to resign after he was caught on a surveillance video stealing beer from a warehouse and was implicated in the theft of empty beer kegs.REF After being escorted off the premises, he returned with two handguns and opened fire on his former co-workers.REF Thornton called 911 and informed the operator that his shooting was motivated by racism he experienced in the workplace.REF There are no indications he suffered from a mental illness.

A similar incident occurred in 1986 in Edmond, Oklahoma. Postal worker Patrick Sherrill was facing possible dismissal due to management concerns over his job performance and reprimands for irritable behavior.REF One day after being verbally disciplined by his supervisors, Sherrill arrived at work with three handguns, shooting and killing 14 co-workers before killing himself.REF Like Thornton, there is little evidence Sherrill was mentally ill in any clinical sense, and official reports on the shooting concluded it was likely the result of job-related frustrations.REF

Mentally Ill Individuals Prone to Violence Committing High-Casualty Acts of Mass Public Violence Without Access to Firearms

While there is certainly an association between untreated serious mental illness and specific types of firearm-related violence such as mass public shootings, this association is too commonly politicized into calls for broad prohibitions on certain types of firearms in the aftermath of mass public shootings. But it is a mistake to focus on the means of violence employed instead of focusing on the underlying untreated serious mental illness that led the individual to violent actions in the first place. Even if it were possible to remove every single one of the almost 400 million privately owned firearms in this countryREF and ensure that no firearms were reintroduced via the black market,REF there are a vast array of alternative means available by which a person can cause equal amounts of harm to himself or others. Mentally ill individuals prone to violence do not need firearms to commit devastating attacks. Consider the follow examples:

  • In 2001, Damir Igric, a mentally disturbed Croatian immigrant with a long history of violent behavior and substance abuseREF attempted to slit the throat of a Greyhound bus driver while traveling near Manchester, Tennessee. Igric eventually succeeded in causing the bus to collide with oncoming traffic, killing seven people (including Igric), and wounding another 35 passengers.
  • That same year, college student David Attias—known around campus as “Crazy Dave”—killed four peopleREF and wounded nine by driving his car down a crowded sidewalk near the University of California, Santa Barbara. Witnesses recalled Attias exiting his car and shouting, “I am the Angel of Death!”REF
  • In 2005, a suicidal man parked his Jeep on the tracks of a commuter train in California, intending to kill himself. Although he changed his mind at the last minute, he left his Jeep to be struck by an oncoming train, resulting in 11 deaths and almost 200 injuries when the train derailed.
  • In 2015, four people were killed and 48 more injured when 25-year-old Adacia Chambers plowed her car through a crowd at Oklahoma State University’s homecoming parade.REF Chambers was initially thought to have been intoxicated but appears instead to have suffered from severe psychosis brought about by undiagnosed bipolar disorder.REF

It is a mistake to focus on the means of violence employed instead of on the underlying untreated serious mental illness that led the individual to violent actions in the first place.

Further, mentally ill individuals intent on committing violence frequently find ways to commit mass killings in countries with even the most restrictive gun control laws. While some of these individuals still have access to firearms,REF as in the United States, there are many available alternatives:

  • In 2010, Zhenf Minsheng, a former community doctor known to suffer from mental illness, went on a stabbing rampage in a Nanping, China, elementary school,REF killing eight children and wounding five after despairing that “life was meaningless.”REF
  • In 2014, an Australian single mother named Raina Thaiday suffered an acute schizophrenic breakdown, during which she stabbed to death all seven of her children. Shortly before the killings, Thaiday’s behavior changed noticeably—she began street preaching about “Papa God,” threw her family’s possessions onto the front lawn, and began “cleansing” her house.REF
  • In 2015, co-pilot Andreas Lubitz locked the captain of Germanwings Flight 9525 out of the cockpit, then deliberately crashed the plane into the French Alps.REF All 150 individuals on board were killed instantly. Lubitz had previously been treated for suicidal tendencies and was declared “unfit to work” by a doctor.REF
  • In 2017, Dimitrious Gargasoulas killed six and wounded another 36 in a vehicular attack on a crowded street in Melbourne, Australia. Investigators disclosed that Gargasoulas had a history of mental health problems and family violence, including stabbing his younger brother for being gay. In the days before the attack, he wrote several “rambling and often nonsensical” posts on social media and made similarly bizarre rants during his court hearings.REF
  • In 2018, just 24 hours after the U.S. media reported the deaths of four individuals at the hands of a mentally disturbed young man at a Tennessee Waffle House,REF a similarly disturbed individual in Toronto, Canada, used a large van to mow down pedestrians, killing 10 and wounding 15.REF

Dealing with the consequences of untreated, serious mental illness necessitates a comprehensive approach that cannot focus simply on the prevalence of firearms within a given community.

Dealing with the consequences of untreated, serious mental illness necessitates a comprehensive approach that cannot focus simply on the prevalence of firearms within a given community. That does not mean there may not be effective and constitutionally sound mechanisms by which to limit a specific individual’s access to lethal means when he or she evidences a heightened risk of danger to self or others.

It does mean, however, that activist groups and politicians who point to mass public shootings as a reason for broad restrictions on firearm access by the general public largely miss the underlying reality: The real problem is not the prevalence of firearms in particular, but the prevalence of untreated serious mental illness that causes some individuals to become violent in catastrophic ways, regardless of lawful access to firearms.


Serious Mental Illness Plays a Significant Role in Violent and Firearm-Specific Crime that Should Not Be Ignored. Taken together, the broader research and specific incidents presented above evidence a strong correlation between serious mental illness—especially when untreated—and specific types of firearm-related violence, such as suicide and mass public shootings. This is not to suggest that individuals with serious mental illness should be treated as community pariahs or that they are the cause of most firearm-related violence in the United States. The connection between the two, however, is not insignificant, and must be accounted for as part of any holistic approach to reducing the prevalence of violent crime in our communities.

The data show that:

  • Most gun deaths in the United States are the result of suicide, not homicide or accident.
  • General rates of firearm access are not significantly related to general suicide rates, even though the risk of suicide for particular at-risk individuals may be lowered by reducing their individual access to prevalent means of committing suicide—including firearms. Several factors other than general firearm access appear to have much more meaningful connections to suicide rates.
  • The presence of serious mental illness substantially increases the risk that a person will commit suicide. Further, access to firearms increases the likelihood that a person with serious mental illness will commit suicide, and many mentally ill individuals who do commit suicide use firearms despite the fact that firearms may generally be less accessible to them.
  • Most people with mental illness are not and will never become violent toward others, but some types of serious mental illness, when untreated, are associated with certain types of violent crime. In particular, the majority of mass public killers suffer from untreated serious mental illness.
  • Even without firearm access, individuals with untreated serious mental illness can and do find ways to commit mass public killings.

This strongly suggests that:

  • While the broad reduction of gun access is not likely to reduce suicide rates, a reduction in suicide rates is likely to correspond with a reduction in firearm-related death rates. This makes suicide prevention a key component of any plan to reduce gun violence. Meanwhile, policies focusing on the reduction of firearm access broadly, across an entire population, are not necessary for the successful reduction of the suicide rate.
  • Policies that focus solely on reducing access to firearms by the seriously mentally ill as a means of lowering their individual risk of suicide may be worthwhile and decrease the likelihood of suicide for some people under some circumstances, but they also fail to grasp the complexity of the issue and should not be the sole means employed to reduce suicide rates.
  • The reduction of suicide rates requires a comprehensive approach that addresses all of the various factors related to suicide risk, such as serious mental illness, socioeconomic variations, and access to support systems—not the broad-scale disarmament of a given population.
  • Policies to reduce the rate of mass public killings in the United States must account for the significant role played by untreated serious mental illness in such killings, instead of focusing largely on the broader availability of firearms.

Part II: The Consequences of Deinstutionalizing the Severely Mentally Ill

Part III: The Current State of Laws Regarding Mental Illness and Guns

—John G. Malcolm is Vice President of the Institute for Constitutional Government, Director of the Edwin Meese III Center for Legal and Judicial Studies, and Ed Gilbertson and Sherry Lindberg Gilbertson Senior Legal Fellow at The Heritage Foundation. Amy Swearer is a Legal Policy Analyst in the Meese Center.


John Malcolm
John Malcolm

Vice President, Institute for Constitutional Government

Amy Swearer

Visiting Legal Fellow, Meese Center for Legal and Judicial Studies