Finnish-Swedish study analyzes link between psychotropic drugs and homicide risk

http://www.eurekalert.org/pub_releases/2015-06/uoef-fsa052515.php

Public Release: 1-Jun-2015
University of Eastern Finland

A study analysing the Finnish homicide and prescription drug databases discovered that the use of certain drugs that affect the central nervous system are associated with an increased risk of committing a homicide. The greatest risk was associated with the use of painkillers and tranquillizing benzodiazepines, while anti-depressants were linked only to a slightly elevated risk. The study is the first one of its kind in the world.

Professor Jari Tiihonen's research group analysed the use of prescription drugs of 959 persons convicted of a homicide.

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After confounding factors were controlled for, the results show that the use of anti-psychotics was not associated with a significantly increased risk of committing a homicide, whereas the use of anti-depressants was associated with a slightly elevated risk (+31%), and the use of benzodiazepines (drugs used to treat anxiety and insomnia) with a significantly elevated risk (+45%). The study found, rather surprisingly, that the highest increase in the risk of committing a homicide was associated with opiate painkillers (+92%) and anti-inflammatory painkillers (+206%). In persons under 26 years of age, the highest increase in the risk of commit-ting a homicide was associated with opiate painkillers (+223%) and benzodiazepines (+95%). An increase in the risk by, for example, 100% means that the risk doubles. Although the use of intoxicants was present in the ma-jority of the homicides, the differences between the drug groups could not be explained by simultaneous in-toxicant use.

In many cases, benzodiazepines had been prescribed in very high doses and for a long period of time. "Benzo-diazepines can weaken impulse control, and earlier research has found that painkillers affect emotional pro-cessing. Caution in prescribing benzodiazepines and strong painkillers to people with a history of substance abuse is advisable," Tiihonen says.