Ecological studies of antidepressant treatment and suicidal risks

Ongoing discussion of potential benefits and risks of antidepressant treatment with respect to suicidal behaviors includes many ecological, or population-based, correlational studies of temporal or regional trends in suicide rates and rates of usage of modern antidepressants including serotonin-reuptake inhibitors (SRIs). Since this body of research has not been compiled and evaluated, we used computerized literature searching to identify 19 relevant published studies. They yielded heterogeneous findings: only 8/19 found significant inverse correlations between rising sales of modern antidepressants in the 1990s and falling suicide rates not anticipated in the 1980s. Average reductions in suicide rates in the 1990s (10.7%) and 1980s (10.0%) differed little in 11 studies with data from both eras. Reduction of suicide rates in the 1990s was unrelated to geographic region, population size, units of analysis, publication year, or growth in antidepressant usage, but was greater with higher initial suicide rates, in men, and in older persons. In the same decade, suicides rates decreased in only half of 79 large countries. Overall, these findings yield limited and inconsistent support for the hypothesis that increased use of modern antidepressants might limit suicide risk, and no evidence that the risk increased. Suicidal risk is determined by complex factors, including access to clinical services, in general, and more comprehensive treatment of depression, in particular. Overall, as with findings from randomized trials and cohort or case-control studies, evidence of specific antisuicidal effects of antidepressant treatment from ecological analyses remains elusive.