How much mental illness actually affects crime

Serious mental illness may not have the effect on crime you actually think it does.

Many people in United States prisons are in jail for reasons that don’t have anything to do with their mental illnesses. How society views violence and mental illness does not reflect reality.

Multiple studies in the past have been done to test the correlation between mental illnesses and crime. A study done around 2014 shows that mental illness doesn’t have as big an effect on crime as one would think.

“Researchers analyzed 429 crimes committed by 143 offenders with three major types of mental illness and found that 3 percent of their crimes were directly related to symptoms of major depression, 4 percent to symptoms of schizophrenia disorders and 10 percent to symptoms of bipolar disorder.” (Researchers at American Psychological Association.)

Some crimes can be seen as a side effect of the offender. But, typically, people with mental illness are less likely to commit a crime. There are few instances where this is the opposite. Certain mental illnesses affect the mind more drastically, and are more likely to have crime as a side effect.

In an interview with Dr. Thatcher, CMO for Valley Behavioral Health, he said, “ To give you an idea of how rarely mental illness causes crime let’s look at the rate of defendants qualifying to plead not guilty by reason of insanity. Basically, for every 1,000 defendants, only 25 attempts to get a conviction of not guilty by reason of insanity, and only about 3 to 5 get that decision in their case. So, that means that less than 1% of crimes are determined to be caused by mental illness and 99% are not.”

“Most persons with serious mental illness are never violent.  However, small subgroups of persons with serious mental illness are at increased risk of violence during certain high-risk periods, such as during a first-episode of psychosis and the period surrounding inpatient psychiatric hospitalization.”

Substance abuse is considered a mental illness, changing the statistics of people jailed because of mental illnesses drastically. According to, 45.5% of all American inmates are imprisoned because of drug offenses.

Drug abuse is considered a mental illness because it affects the brain. “The brain is where your emotions happen and are regulated. It is the place where your interpretation of the world inside and outside of your body takes place.” Thatcher says, “Drug abuse is the disorder of continued use of a drug that is clearly causing problems yet you’re unable to stop even though you want to. All of that action takes place in the brain, so that’s why it’s considered a mental illness.”

The most common mental illnesses that have greater effects on those who commit crimes are extremely severe. They are not basic mental illnesses, but controlling and need to be treated and taken seriously. These such illnesses are schizophrenia, major depression, and bipolar disorder. (

Severe mental Illnesses are less common and need to be treated, but society also has a role. “The first step is to recognize there’s a problem. The second step is to get an evaluation done by a mental health professional. The third step is to follow the recommendations of the mental health professional whether that be therapy, medications, or both.”