Objective: Ecological studies have demonstrated a substantial decrease in suicide in parallel with an increase in the use of antidepressants. Causality cannot, however, be inferred from such studies. The aim of this study was to test on the individual level the hypothesis that treatment with antidepressant medication has been a substantially contributing cause of the decrease in suicide.
Method: Time trends in the detection of antidepressants and five ‘control medications’ in the forensic toxicological screening of 16 937 suicides and 33 426 controls in Sweden 1995–2005.
Results: The expected number of antidepressant-positive suicides in 2005 was 409 if the hypothesis was true and 603 if it was false. The observed number in 2005 was 420. The control medications were detected to the extent that was expected if not preventing suicide.
Conclusion: The observed trend in the number of suicides with antidepressants was well predicted by the hypothesis that the increased use of antidepressants has been a substantially contributing cause of the decrease in suicide.