Some 30,000 people die annually by suicide in the United States… with more than half of these deaths occurring while the victim was suffering a largely untreated bout of depression.
Around 1990, a new class of antidepressants, called selective serotonin reuptake inhibitors or SSRIs, came on the market.
Before then, drugs called tricyclic anti-depressants (TCAs) dominated pharmaceutical treatment of depression… but they pose a risk of accidental poisoning (or deliberate suicide) by overdose.
Sales of SSRIs such as Prozac, Zoloft, and Paxil have increased annually over the past 20 years, while sales of the older TCA drugs have declined substantially.
And suicide rates have fallen since the end of the 1980s in many Western countries.
So you'd think that this relationship proves the life-saving power of newer, Prozac-type anti-depressants.
Indeed, an analysis of U.S. public health data by University of Illinois researchers found a link between the rise in sales of SSRIs and a roughly simultaneous drop in America's suicide rate.
As they wrote, “…increases in prescriptions for SSRIs are associated with lower suicide rates and may reflect antidepressant efficacy, compliance [with SSRI prescriptions], a better quality of mental health care, and low toxicity [versus TACs] in the event of a suicide attempt by overdose” (Gibbons RD et al. 2005).
But despite the correlation between greater use of SSRIs and lower suicide rates in Western countries, a recent analysis by Norwegian researchers found no evidence that Prozac and company account for the reduced suicide rates also seen in Scandinavia since 1990 (Zahl PH et al 2010).
Nor did the researchers find any relationship between falling suicide rates and steadily sinking sales of older, more toxic TACs, which the University of Illinois team speculated might explain part of the suicide decline.
Declining suicide rates, but no evidence that SSRIs did the trick
The suicide rate has been declining in America, Norway, Sweden, Denmark, and Finland over the past 20 years.
A Norwegian research team gathered data from the four Nordic nations, and examined the relationship between changes in suicide rates and changes in sales for both new and older antidepressants from 1990 to 1998 (Zahl PH et al 2010).
During this period, the increase in sales of Prozac and other SSRI drugs was greatest, so that is when the greatest drop in suicide rate would be expected.
The researchers looked at two main questions:
Can a significant increase in sales of SSRIs in any one year be related to a sharp decline in the suicide rate in the same year?
Can the decline in sales of TCAs be related to the decrease in the suicide rate?
When the Nordic countries were studied as one group, the answers to both questions was “no”.
A previous study by other Norwegian researchers found a correlation between the increase in sales of SSRIs and a decrease in Norway's suicide rate in at the beginning of the 1990s (Bramness JG et al. 2007).
Just as the University of Illinois team speculated, the authors of that 2007 Norwegian study suggested that the drop in suicide rates could be explained in part by the fact that fewer people received older TCA drugs, which they could use to commit suicide.
But no such link between reduced sales of TAC drugs and reduced suicide rates was detected in the new study, which included all Nordic countries.
The researchers behind the study conclude that the suicide rate is not affected by sales of antidepressants, but instead is influenced by other factors that are little understood and are difficult to measure.
Bramness JG, Walby FA, Tverdal A. The sales of antidepressants and suicide rates in Norway and its counties 1980-2004. J Affect Disord. 2007 Sep;102(1-3):1-9. Epub 2007 Jan 16.
Fournier JC et al. Antidepressant Drug Effects and Depression Severity: A Patient-Level Meta-analysis. JAMA. 2010;303(1):47-53.
Freeman MP, Mischoulon D, Tedeschini E, Goodness T, Cohen LS, Fava M, Papakostas GI. Complementary and alternative medicine for major depressive disorder: a meta-analysis of patient characteristics, placebo-response rates, and treatment outcomes relative to standard antidepressants. J Clin Psychiatry. 2010 Jun;71(6):682-8.
Gibbons RD, Hur K, Bhaumik DK, Mann JJ. The relationship between antidepressant medication use and rate of suicide. Arch Gen Psychiatry. 2005 Feb;62(2):165-72.
Zahl PH, De Leo D, Ekeberg Ø, Hjelmeland H, Dieserud G. The relationship between sales of SSRI, TCA and suicide rates in the Nordic countries. BMC Psychiatry. 2010 Aug 6;10:62.