Background: Although selective serotonin reuptake inhibitors (SSRIs) are widely prescribed, associations with violence are uncertain.
Methods and findings: From Swedish national registers we extracted information on 856,493 individuals who were prescribed SSRIs, and subsequent violent crimes during 2006 through 2009. We used stratified Cox regression analyses to compare the rate of violent crime while individuals were prescribed these medications with the rate in the same individuals while not receiving medication. Adjustments were made for other psychotropic medications. Information on all medications was extracted from the Swedish Prescribed Drug Register, with complete national data on all dispensed medications. Information on violent crime convictions was extracted from the Swedish national crime register. Using within-individual models, there was an overall association between SSRIs and violent crime convictions (hazard ratio [HR] = 1.19, 95% CI 1.08-1.32, p < 0.001, absolute risk = 1.0%). With age stratification, there was a significant association between SSRIs and violent crime convictions for individuals aged 15 to 24 y (HR = 1.43, 95% CI 1.19-1.73, p < 0.001, absolute risk = 3.0%). However, there were no significant associations in those aged 25-34 y (HR = 1.20, 95% CI 0.95-1.52, p = 0.125, absolute risk = 1.6%), in those aged 35-44 y (HR = 1.06, 95% CI 0.83-1.35, p = 0.666, absolute risk = 1.2%), or in those aged 45 y or older (HR = 1.07, 95% CI 0.84-1.35, p = 0.594, absolute risk = 0.3%). Associations in those aged 15 to 24 y were also found for violent crime arrests with preliminary investigations (HR = 1.28, 95% CI 1.16-1.41, p < 0.001), non-violent crime convictions (HR = 1.22, 95% CI 1.10-1.34, p < 0.001), non-violent crime arrests (HR = 1.13, 95% CI 1.07-1.20, p < 0.001), non-fatal injuries from accidents (HR = 1.29, 95% CI 1.22-1.36, p < 0.001), and emergency inpatient or outpatient treatment for alcohol intoxication or misuse (HR = 1.98, 95% CI 1.76-2.21, p < 0.001). With age and sex stratification, there was a significant association between SSRIs and violent crime convictions for males aged 15 to 24 y (HR = 1.40, 95% CI 1.13-1.73, p = 0.002) and females aged 15 to 24 y (HR = 1.75, 95% CI 1.08-2.84, p = 0.023). However, there were no significant associations in those aged 25 y or older. One important limitation is that we were unable to fully account for time-varying factors.
Conclusions: The association between SSRIs and violent crime convictions and violent crime arrests varied by age group. The increased risk we found in young people needs validation in other studies.