Antidepressants may increase the risk of death, according to a Canadian study.
The study, published in Psychotherapy and Psychosomatics, found that the effect of antidepressant use on all-cause mortality depends on cardiovascular health.
A McMaster University-led team of researchers reviewed studies involving hundreds of thousands of patients in a meta-analysis. These studies estimated the risk of death from any cause associated with using antidepressants, and usually followed large cohorts of participants taking antidepressants over time and compared them to people not taking antidepressants, while controlling for other important demographic and health-related variables. When researchers statistically pooled these estimates together, they were able to determine the overall net effect of using antidepressants on mortality.
The study was completed because the researchers suspected that the way antidepressants work could have adverse long-term effects on health, based on some previous theoretical work, says author Paul Andrews, an associate professor at McMaster University, Hamilton, Ontario, Canada, who led the research team.
“Antidepressants disrupt the functioning of monoamines—biochemicals such as serotonin and dopamine—and these monoamines have important functions not only in the brain, but all over the body,” he says.
“For example, serotonin affects growth, reproduction, digestion, immune function, and many other processes, and it is found in almost every major organ,” Andrews says. “Disrupting the functioning of serotonin can therefore have different adverse effects, which can contribute to a risk of death in many different ways. We completed the study to test the hypothesis that interfering with the functioning of monoamines by using antidepressants can increase the risk of death from any cause.”
The study found that antidepressant users had a 33% higher chance of death than non-users. Antidepressant users also had a 14% higher risk of cardiovascular events, such as strokes and heart attacks.
“Taking antidepressants does not appear to affect the risk of death from any cause for individuals who have pre-existing cardiovascular conditions,” says McMaster researcher and co-author Marta Maslej. “However, in general population samples [i.e., individuals with no specified cardiovascular illness], using antidepressants is associated with a 33% increased risk of death from any cause. To put this finding into context, if unmedicated depression leads to eight deaths per 1,000 person-years, antidepressant use is estimated to cause an additional 2.64 deaths per 1,000 person-years.”
The study findings cast doubt on widely-held assumptions that antidepressants are relatively safe, and that they save lives by reducing depression-related mortality, Maslej says.
“In our meta-analysis, we only included studies that attempted to isolate the effects of antidepressant use on mortality by controlling for a variety of important variables, including depression,” she says. “Because general population samples taking antidepressants were still at an increased risk of death, relative to those not taking antidepressants, our findings suggest that the risk of death associated with using antidepressants may be greater than the risk of death associated with unmedicated depression. In other words, antidepressants could take more lives than they save.”