Individuals between the ages of 15 and 24 are more likely to commit a violent crime if they are taking an SSRI antidepressant than if they are not, according to new research out of Sweden. The study published in PLoS Medicine on Tuesday, suggests “warnings about the increased risk of violent behavior among young people taking SSRIs might be needed.”
In the US about “one in ten people over 12 years old take antidepressants,” drugs intended for the treatment of depression but that are also prescribed for many other mental health conditions. Selective serotonin reuptake inhibitors, or SSRIs, are the newest form of antidepressant drugs and have been available since the late 1980s.
Experts believe that antidepressants “treat depression by increasing serotonin levels in the brain,” and that SSRIs such as fluoxetine (Prozac) and paroxetine (Paxil or Seroxat) accomplish this by blocking the reuptake of serotonin after it delivers a message between nerve cells. Though, as Whitaker (2010) and other researchers have noted, it is not evident that low serotonin levels are the cause of depression.
In 2007, the FDA issued a warning requiring antidepressant manufacturers update their black box warnings to include the risks of suicidal thoughts and behaviors in youth, but there is also “limited and inconclusive evidence linking SSRI use with violent behavior.”
A team of researchers, led by Yasmina Molero, used data on SSRI prescriptions in Sweden from 2006 to 2009 and compared it with violent crime conviction records from the Swedish national crime register. The study design allowed the team to compare individuals to themselves. By comparing individuals behavior while they were on and off the SSRIs, the study avoided many potentially confounding factors.
Using the “within-individual” statistical models, Molero and her team found “a significant but modest overall association (an association unlikely to have occurred by chance) between SSRIs and convictions for violent crime.”
“After adjustment for age, the association between SSRIs and convictions for violent crimes remained significant for individuals aged 15 to 24 years but became non-significant among older individuals.”
These findings are limited by the inability of the study to account for all other risk factors and can’t “prove that taking SSRIs actually causes an increase in violent crime among young people.” They do, however, “show an association between SSRIs and violent crime that varies by age group.”
“If our findings related to young people are validated in other designs, samples, and settings,” the researchers conclude, “warnings about an increased risk of violent behaviours while being treated with SSRIs may be needed.”
For coverage of the study by Reuters click here →
Molero Y, Lichtenstein P, Zetterqvist J, Gumpert CH, Fazel S (2015) Selective Serotonin Reuptake Inhibitors and Violent Crime: A Cohort Study. PLoS Med12(9): e1001875. doi: 10.1371/journal.pmed.1001875 (Full Text)