If an event doesn’t happen often, it’s difficult to predict when it will happen next. We can only talk about “risk factors”.
For example, no one can predict when an earthquake will occur. We can, however, talk about the risk of an earthquake. We know that the risk of an earthquake is much higher in Seattle than in Houston: Seattle is on a fault line while Houston is not. Because earthquakes are rare, though, we don’t know when Seattle will have an earthquake. We just know that it’s more likely to happen there than in Houston.
Homicide is also a rare event. In 2013, about five out of 100,000 people died from homicide. That means 99,995 out of 100,000 people did not die from homicide that year.[1. A reader told me that these numbers are confusing. More than 100,000 people died in the US in 2013. My point is that the vast majority of people don’t die from homicide. Communication is hard.] Compare that with suicide: In the same year about 13 out of 100,000 people died from suicide. That’s right: In the US, people are over twice as likely to kill themselves than other people.
Because homicide is such a rare event, it is difficult to predict when, where, and how it will occur. We can discuss risk factors (e.g., alcohol and other substance use; access to firearms; gang involvement; exposure to domestic violence and child abuse; previous history of fighting of violence), but none of those risk factors will help us predict when it will happen. There are adults who were beaten as children, drink alcohol now, and own a firearm… but they will never kill anyone.
The data is mixed about the association between mental illness and homicide.[2. Here are three papers that discuss mental illness and suicide:
- Patients with mental illness as victims of homicide: a national consecutive case series.
- Mental illness in people who kill strangers: longitudinal study and national clinical survey.
- Mental illness and domestic homicide: a population-based descriptive study.
] Based on numbers alone, though, it is both inaccurate and unfair to state that homicide is due to psychiatric conditions alone:
- Major depression: 7 out of 100 people
- Alcohol use disorder: 7 out of 100 people
- Bipolar disorder: 3 out of 100 people
- Schizophrenia: 1 out of 100 people
Compare that to the rate of homicide: 5 out of 100,000 people.
With increasing news reports of people killing others, my colleagues and I have wondered how we can intervene. Many people who have committed homicide have never encountered the mental health system. Even if they did, they may not have endorsed or demonstrated symptoms that would warrant any intervention, including a follow-up visit. We agree that individuals who kill others are disturbed, but they may not have a “mental illness” that is described in our field. (We then wonder: So what is going on with them?)
The book The Spirit Level describes the correlation between greater interpersonal violence in societies with greater inequality. The authors also show evidence of higher prevalences of psychiatric disorders, obesity, and teen pregnancies in societies that are more unequal.
While it is easier to attribute these acts of heartbreaking violence to individuals—They are the problem; this happens because They are “mentally ill”; Their religion dictates that They should kill people; We would never do that—perhaps we should attribute this violence to our society and our communities (or lack thereof).
How would our society function if everyone had food, clothing, and a home? What would happen if everyone had steady employment and income? How would relationships change if everyone in school and at work learned how to recognize their emotions and practiced coping skills? What would happen if people didn’t drink, use drugs, or resort to violence when feeling distressed? What would shift if everyone had the chance to go to school and learn about different people, places, and ideas? How would things be different if people didn’t feel hopeless and helpless? What if people believed their communities could create something better? What if people didn’t believe that the only solution involves destruction?
It is easy to blame Them: They have mental illness; They believe in a religion that is false; there is something wrong with Them.
They and We, however, are part of the same community. Until we realize that we must work together to reduce risk factors and help each other, we cannot expect that these tragic events will stop.
Maria Yang, MD 