First the good news: Suicide rates among younger and older Americans have been declining since the early 1990s.

Now the puzzling news: No one really knows why.

'For 40 years suicide rates had been rising among adolescents," said Robert McKeown, an epidemiology professor in USC's Arnold School of Public Health. "They began to decline in the late 1980s for adults 65 and older and in the early 1990s for adolescents and young adults, but many people weren't aware; they kept saying suicides were increasing when it was no longer true."

McKeown presented his findings on suicide rates at the National Press Club in Washington Sept. 28. His talk was part of a forum, "Out of the Shadows: Exploring the Barriers to Mental Health, Prevention, and Treatment," sponsored by the American Public Health Association in collaboration with the Community Voices Initiative of the National Center for Primary Care at the Morehouse School of Medicine.

McKeown had tracked suicide rates for several years for research and teaching purposes and noticed the trends had reversed and rates had begun to decline among adolescents, young adults, and older adults--those younger than 25 and older than 64. He recruited S.C. College of Pharmacy professor Richard Schulz and School of Medicine neuropsychiatry professor Steven Cuffe to help explore possible explanations for the improvements.

Their discussion of these findings, published in the October issue of the American Journal of Public Health, suggests several possibilities as to why those suicide rates have fallen. The research also raises questions about why suicide rates among the middle groups--those 25 to 64--have not declined.

"In our medical literature searches, we began finding international studies that suggested a correlation of declining suicide rates with an increase in the use of new-generation antidepressants," McKeown said. "But you can't blithely assume that drugs like Prozac have lowered the suicide rate--if that was the reason, why haven't the suicide rates of those in the 25 to 64 age brackets declined, too?"

From 1994 to 2003, suicide rates declined 30 percent among adolescents and young adults; among older adults, the suicide rate fell 33 percent from 1987 to 2003. Despite the decline, suicide remains the third-leading cause of death among adolescents behind accidents and homicide. Among older adults, suicide is surpassed by several chronic disease conditions as a leading cause of death.

"We need to understand how something this significant could turn on a dime," McKeown said.

That understanding is particularly important now that the Food and Drug Administration is warning physicians about the risk of increased suicides and suicidal behavior ideas and attempts, particularly among children, associated with the use of SSRI-type antidepressants.

"We aren't trying to argue that these drugs are harmless," McKeown said. "But the possible correlation between the advent of new antidepressants and the decline in suicide rates needs to be better explored."

It might be that there is no association at all.

"It could be that as antidepressants help a patient's depression improve, that person becomes more energetic, less apathetic, and better able to make decisions," McKeown said. "If a patient remains suicidal as depression decreases, the risk for suicidal behaviors might increase."

The researchers offered another possible reason for the decline in some suicide rates that has nothing to do with antidepressants. Some of the studies they surveyed attributed the decline in American homicide rates to improved trauma care. In that scenario, the number of murder attempts did not decline--but the number of actual homicides was reduced by better medical care.

"It could be that the number of attempted suicides hasn't gone down. We might just have better trauma care that keeps more people alive after attempting to take their own lives," McKeown said.

Other variables that might have contributed to the decline in suicides could include an improved economy and an increase in healthy life expectancy.

"Our interest in this research was stimulated, in part, by our curiosity about why suicide rates among some groups had fallen so dramatically," McKeown said. "Having completed this study, our perplexity remains."

McKeown, his colleagues, and the S.C. Rural Health Research Center are now seeking research funding to delve deeper into data that could shed more light on the issue.

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