June 13, 2006 |
Suicide rates in the US fluctuated from the early 1960s until 1988, after which they showed a gradual decline that might have been linked to the introduction of the antidepressant fluoxetine (Prozac), according to a new study in PLoS Medicine.
Michael Milane and colleagues (University of California, Los Angeles) analyzed suicide rates in the US general population from 1960-2002. Suicide rates fluctuated between 12.2 and 13.7 per 100,000 until 1988, and then gradually fell, with the lowest value of 10.4 per 100,000 in 2000.
The researchers also analyzed data on prescriptions of fluoxetine, which was introduced in 1988. There was an increase in the number of fluoxetine prescriptions, from about 2.5 million in 1988 to over 33 million in 2002.
Mathematical tests showed that the steady decline in suicides was statistically associated with the increased number of fluoxetine prescriptions (the more prescriptions, the fewer suicides). The authors hypothesize that fluoxetine might have saved 33,600 lives since its introduction.
Milane and colleagues acknowledge that the association they found between the fall in suicides and the introduction of fluoxetine cannot prove that the medication caused the fall. There may have been other reasons why the suicide rate declined.
Nevertheless, they argue that their findings are helpful in shedding light on the ongoing debate about whether fluoxetine (and other “SSRI antidepressants”) might trigger an increase in suicide. “Although the current issue concerning antidepressants and suicidality requires further examination,” they say, “we believe that many more lives have been saved than lost since the advent of these drugs.”
In a commentary on the new study, Bernhard Baune and Philippa Hay (James Cook University, Australia), who were not involved in the study, say that the type of study performed by Milane and colleagues cannot prove for certain “whether antidepressants do harm or good at a population level.” Nevertheless, they say that the study “does not support an association between increased suicide and increased fluoxetine prescription rates.”