Published: 01-06-2015 09:10 | Updated: 01-06-2015 11:04

Study analyses link between psychotropic drugs and homicide risk

A new study published in the journal World Psychiatry shows that the use of certain drugs that affect the central nervous system may be associated with an increased risk of committing a homicide. The greatest risk was recorded in the use of tranquillizing benzodiazepines and painkillers, while anti-depressants were associated only to a slightly elevated risk.

In recent years, there has been plenty of debate over whether psychotropic drugs, and especially anti-depressants, can cause violent behaviour. In particular, this debate has been fuelled by massacres committed by young persons in schools and other public places in the US and other countries, too. To investigate this claimed link between certain drug use and crime, the international research team, led by Professor Jari Tiihonen at Karolinska Institutet’s Department of Clinical Neuroscience, analysed the use of prescription drugs of 959 persons convicted of a homicide in Finland during 2003 to 2011.

The registers used were the Finnish Homicide Database of the Institute of Criminology and Legal Policy, and the Finnish Prescription Register of the Social Insurance Institution of Finland. 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, and the use of benzodiazepines (drugs used to treat anxiety and insomnia) with a significantly elevated risk.

Anti-inflammatory painkillers

Somewhat surprisingly, the study also found that the highest risk of committing a homicide was associated with opiate painkillers and anti-inflammatory painkillers. Although the use of intoxicants was present in the majority of the homicides, the differences between the drug groups could not be explained by simultaneous intoxicant use.

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

The study was carried out in collaboration between Karolinska Institutet and several organisations in Finland; the University of Eastern Finland, Niuvanniemi Hospital, the National Institute for Health and Welfare, the National Research Institute of Legal Policy, Kuopio University Hospital, Helsinki University Hospital, the University of Helsinki, the Kela Research Department, and Epid Research Ltd. This news article is an abbreviation of a press release from University of Eastern Finland.


Psychotropic drugs and homicide: a prospective cohort study from Finland
Tiihonen J, Lehti M, Aaltonen M, Kivivuori J, Kautiainen H, Virta L, Hoti F, Tanskanen A, Korhonen P
World Psychiatry 2015, Epub June 1, 2015, doi: 10.1002/wps.20220