Study Links Painkillers to Homicides

By Pat Anson, Editor

You can add the term “homicidal” to the list of stigmas faced by chronic pain patients.

A new study in the journal World Psychiatry has found that certain drugs that affect the central nervous system – particularly opioid painkillers – significantly increase the risk of committing murder.

The Swedish and Finnish researchers behind the study wanted to know if there was any scientific basis for the claim that anti-depressants and other psychotropic drugs can cause violent behavior. It’s an issue that was debated after massacres committed by young people in schools and other public places in Finland and around the world.

"It has been repeatedly claimed that it was the anti-depressants used by the persons who committed these massacres that triggered their violent behavior. It is possible that the massive publicity around the subject has already affected drug prescription practices," said lead author Jari Tiihonen of the Karolinska Institute in Sweden.

In one of the first studies of its kind, researchers analyzed a database of 959 people convicted of homicide in Finland between 2003 and 2011 to see what medications they were taking before their crimes.  

They found that anti-psychotic medication was not associated with a significantly increased risk of homicide, and there was only a slightly elevated risk for most people taking anti-depressants and benzodiazepines – drugs used to treat anxiety and insomnia.

But the study did find, rather surprisingly, that there was a significantly higher risk of committing a homicide associated with opioid pain medications like oxycodone and tramadol (93% higher) and anti-inflammatory pain relievers such as acetaminophen (206% higher).

The risk was even more elevated for young people. For someone under the age of 26, there was a 223% greater chance of them killing someone if they were taking opioids. Young people taking benzodiazepines had a 95% greater risk.

"Benzodiazepines can weaken impulse control, and earlier research has found that painkillers affect emotional processing. Caution in prescribing benzodiazepines and strong painkillers to people with a history of substance abuse is advisable," Tiihonen concluded.

Although alcohol and other intoxicants were also involved in a majority of the homicides, the researchers said their use did not explain the differences between the drug groups.

In 2007, an 18-year old Finnish high school student named Pekka-Eric Auvinen fatally shot eight people at his school before taking his own life. He had been taking anti-depressants for a year prior to the massacre.

The Citizens Commission on Human Rights UK has a list of several other massacres around the world linked to the use of anti-depressants. Opioids are not mentioned in any of the examples.