Analgesics Linked to Increased Homicide Risk

Liam Davenport

June 11, 2015

Psychotropic medications, including antidepressants, benzodiazepines, and particularly opiate and nonopiate analgesics, are associated with a significantly increased risk for homicide, new research shows.

Jari Tiihonen, MD, PhD, professor, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden, and colleagues found that antidepressants increase the homicide risk by 31% and that benzodiazepines increase the risk by 45%.

Further, the use of opiate and nonopiate analgesics was associated with a two- and threefold increased risk for homicide, respectively. Interestingly, antipsychotics were not associated with an increased homicide risk.

"The surprisingly high risk associated with opioid and non-opioid analgesics deserves further attention in the treatment of pain among individuals with criminal history," the investigators note.

The research was published online June 4 in World Psychiatry.

Great Debate

There has been debate as to whether psychotropic medications can cause violent behavior, especially in light of several massacres committed by young people in recent years, including in the United States and Finland.

"Antidepressants have especially been blamed by non-scientific organizations for a large number of senseless acts of violence," the authors write.

"It is likely," they add, "that such massive publicity in the lay media has already led a number of patients and physicians to abstain from antidepressant treatment, due to the perceived fear of pharmacologically induced violence," they add.

To determine whether current antidepressant treatment was associated with an increased risk for homicide, the investigators prospectively collected data on 959 individuals who committed a homicide between 2003 and 2011. For each offender, 10 population control participants were picked from the Finnish Population Information System; these individuals were matched for sex, age by year of birth, and home municipality at the time of each homicide.

In addition, information on medication use from 1995 to 2011 was obtained for all case participants and control participants via linkage to the nationwide Finnish Prescription Register, with a current user being someone who was using a given drug at the time of the homicide/control matching.

After taking into account potential confounding factors, the researchers found that for current use vs no use, the adjusted relative risk (RR) of committing a homicide was 1.31 for antidepressants (P = .022), 1.45 for benzodiazepines (P = .001), and 1.10 for antipsychotics (P = .54).

Lowered Impulse Control

The current use of opioid and nonopioid analgesics was associated with a significantly increased risk of committing a homicide (RR, 1.92 and 3.06, respectively; P < .001 for both).

When restricting the analysis to offenders aged 25 years or younger, the only associations with committing homicides that approached significance were for current use of opioid analgesics and benzodiazepines (RR, 3.22 and 1.95, respectively; P = .04 and P = .07, respectively).

"Benzodiazepines can weaken impulse control, and earlier research has found that painkillers affect emotional processing," said Dr Tiihonen.

"The surprisingly high risk associated with opioid and non-opioid analgesics deserves further attention in the treatment of pain among individuals with a criminal history," the authors write.

The investigators also note that although antidepressant use was associated with a risk for homicide, the risk reached borderline statistical significance, whereas benzodiazepine and analgesic use was linked with a much higher risk for homicide. This finding "remained highly statistically significant even after correction for multiple comparisons."

These results, they write, "imply that the use of antidepressants should not be denied to either adults or adolescents due to a presumed risk of homicidal behavior."

The authors report no relevant financial relationships.

World Psychiatry. Published online June 4, 2015. Abstract

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