Mental Illness Isn’t Driving Violent Crime
Mental illness combined with substance abuse increases the risk of violent crime, but research shows that isn’t driving overall trends, especially for random violence.
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Last month, I wrote a “thinking-out-loud” post on how we might have a more useful conversation about guns. It generated quite a bit more response than I expected. Some of the comments below the post were heated, but also mostly productive — with a few exceptions, of course. Overall, I learned, and was encouraged by the tenor of the discussion.
Today I’d like to think out loud a bit about the most common response I received: that the epidemic of gun deaths in the United States is really a mental health problem.
This is certainly not an area of expertise for me. That said, the mental-health response comprises a hypothesis, and I think one way to elevate the level of discussion is to take that hypothesis and look for evidence that bears on it.
This is an important and topical discussion; I think bringing something other than pure intuition to the table can make any discussion both more interesting and more productive. So…
Hypothesis 1: Violent crime is driven by mental illness.
Some of the most interesting data I’ve come across so far is from Sweden — thanks to the country’s national registers of hospital admissions and criminal convictions. I’m not suggesting we blithely extrapolate this to the rest of the world, but here’s the upshot:
“Persons with psychoses are about four times more likely than the general population to have been convicted of a violent crime but the psychotic group accounts for just 5% of such offenses.”
Psychosis means a severe mental disorder that includes a disconnect from reality. This finding indicates that such severe mental illness does increase the risk of perpetrating a violent crime, but because such illness is rare, those crimes are a drop in the bucket overall.
The U.S. data is more scattered than the Swedish data, but it doesn’t tell a wildly different story. For example:
“Databases that track gun homicides, such as the National Center for Health Statistics, similarly show that fewer than 5% of the 120,000 gun-related killings in the United States between 2001 and 2010 were perpetrated by people diagnosed with mental illness.”
From the studies I’ve read thus far, I’d say this is an emerging theme across countries: certain mental illnesses can increase the risk of violent crime, but public perception represents “an exaggeration of the ‘threat’ associated with these disorders,” as one paper put it. Several of the papers I read pointed out that people with mental illness are far more likely than their peers to be victims of violent crime.
My working notion is that hypothesis 1 is probably false. That data I’ve seen so far doesn’t support the idea that mental illness is a driving force in the overall quantity of violent crime. Which leads me to my hypothesis 2….
Hypothesis 2: The public wildly overestimates the danger associated with mental illness.
To give the conclusion up front: papers I’ve read so far suggest to me that this is definitely true. (See, for example, the section of this paper titled: “The assumption that mental illness causes gun violence.”) But I’m also interested in why this is the case. One passage in an overview paper particularly resonated with me:
“The public most fear violence that is random, senseless, and unpredictable and they associate this with mental illness. Indeed, they are more reassured to know that someone was stabbed to death in a robbery, than stabbed to death by a psychotic man.”
Years ago — when I was trying to complete my transition from aspiring scientist to journalist — I got my first steady journalism job as the overnight reporter at the New York Daily News. (This was known as the “lobster shift", a term for which everyone had a different origin story.) As you might imagine, nothing happy that’s going in the Daily News happens between midnight and 10 a.m. I was usually reporting on murders.
I quickly realized that the very large majority of violent crime was not random, and that when violent crime was random (i.e. targeted at strangers) it inspired much more fear and generated much bigger headlines. Human nature, I suppose. I think reporting on crime is important, but it should also include statistical context.
During that year of crime reporting, I remember that when someone learned my job, they’d often warn: “Watch out for Central Park at night.” I never once reported to Central Park to cover a crime, because violent crime basically never happened in Central Park. And because violent crime basically never happened in Central Park, it was massive news when it did occur.
New Yorkers, it seemed, tended to be most afraid of some of the safest places in the city. When violent crime happened in places where it was generally rare, it was shocking and made for big headlines — and stuck in everyone’s memory. (The “availability heuristic”, or “availability bias”, is a psychological term for the tendency to form opinions based on a single, memorable example of some phenomenon, even when it’s not representative.)
Years later, when I moved to DC and would share that I was a big runner, I was warned several times to stay out of Rock Creek Park at night because Chandra Levy was killed there. What happened to Levy in 2001 was, obviously, horrific. That said, it was fully 12 years before the next homicide investigation in Rock Creek Park.
So what does this have to do with mental illness and perception of violent crime?
My guess is that stories of random violence perpetrated by a psychotic criminal are so dramatic that — like murders in Central Park — they have an outsized impact on public perception, even though they are rare. They present perfect material for our availability-biased brains.
To recap my cursory conclusion for hypothesis 2: people universally overestimate the threat of violence associated with mental illness, probably due to rare but dramatic stories.
Psychiatric Patients Compared to Their Neighbors
Perhaps the most interesting study I came across — and again, I’m just dipping a toe into this literature, but it’s better than my intuition! — was the MacArthur Violence Risk Assessment Study, conducted in the 1990s.
Researchers tracked a thousand patients with mental disorders after they were discharged from hospital psychiatric units in Kansas City, Pittsburgh, and Worcester, Massachusetts. These were men and women between the ages of 18 and 40 who had serious enough mental illness to have been hospitalized.
For a comparison group, the researchers used the patients’ neighbors. That way, they could see if discharged patients were any more or less violent than others given the same socioeconomic context.
Here’s what they found: discharged psychiatric patients were equally likely to commit violent acts as their randomly selected neighbors — if they did not also have substance abuse disorders. Here’s how they explained their results in a magazine letter-to-the-editor:
"Patients who were not substance abusers were no more likely to be violent than were their neighbors. Does this mean that we claim that mental disorder has nothing to do with violence? No. Mental disorder has a significant effect on violence by increasing people's susceptibility to substance abuse. When first discharged, patients were twice as likely as their neighbors to be abusing substances, and alcohol and drugs raised the risk of violence for patients abusing them even more than for others."
The MacArthur Study authors also reported that most violence by discharged patients did not involve a weapon or result in serious injury, and was not random. Usually, violence was directed at family members or others who lived with the discharged patient. As the researchers wrote:
“People with mental disorders are less likely than people without such disorders to assault strangers and to commit assaults in public places.”
In terms of violent crime targeted at strangers, their results showed that there was more to worry about from the control group than the discharged-patient group.
I am not well read in this area, but I found this back and forth between the MacArthur researchers and a pair of critics to be fascinating in terms of highlighting important questions.
Keeping Perspective
The overwhelming sense I got from the studies I mentioned here, as well as others I read but didn’t include: it is right to be concerned about the association between mental illness and violence — particularly when it intersects with substance abuse — but mental illness is absolutely not the primary, or even a particularly large factor in overall homicides. That is even more true when it comes to violent crime perpetrated against strangers.
For what it’s worth, this comports with my experience on the lobster shift. There were about 550 murders in New York City over that year; I estimate that I had a hand in reporting on at least 50 of them — a pretty decent sample. Almost all of them involved impulsive shooting — usually by boys or men in their teens or twenties — during an argument, or a drug deal or related dispute. (Research supports the idea that the large majority of shootings involve people in the same social network.) On the infrequent occasions it was something else, it made big news.
As an aside, I think it’s worth noting that despite a recent uptick in homicides in the U.S., the homicide rate is lower than it was in the 1970s, ‘80s, and ‘90s. Many of the messages I got about the gun-violence post suggested that we’re in a time of unprecedented mental illness and random violence. I don’t know about the former — although suicide rates are higher than in the past — but the latter is certainly not true.
Lastly, some commenters on the gun post expressed earnest concern about how potential gun-control laws might infringe on individual rights. I appreciated that discussion, and it got me thinking about infringement on individual rights by forced mental health treatment. I happen to be related to an expert in mental health law. If you found this post interesting, and would like to learn a bit about what it takes to force an adult with a mental illness to receive treatment, let me know in the comments. Perhaps a topic for a future post…
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Until next time…
David
P.S. Update: a number of readers asked for reading recommendations. I think this (free) journal article did a nice job providing extensive background.
Photo credit: bubaone / Getty Images