Suicide risk highest when first starting antidepressants
July 20, 2004

The risk of suicidal behavior increases within a month of starting any of four commonly prescribed antidepressants, a new study says, but researchers caution that this could be due to the time it takes the drugs to work in those already considering suicide.

The study involved nearly 2,800 British adults and children ages 10 to 69 who were first-time users of any one of four drugs between 1993 and 1999.

Researchers reported Wednesday in the Journal of the American Medical Association that nonfatal suicidal behavior was four times more likely to occur within 10 days after receiving a first antidepressant prescription than in those who had been taking the drug for more than three months. Overall, patients were almost three times as likely to exhibit such behavior during the first month.

And suicide was almost 40 times more common early on than later in treatment, although there were just 17 suicides among the study group.

But the researchers also concluded there was no substantial difference in the effect of the four drugs on people ages 10 to 19 years old.

The study confirmed regulators' worries that patients need to be more closely watched for suicidal tendencies when they're first put on antidepressants. However, the report did not give much new insight into whether the drugs and particularly those that affect the brain hormone serotonin were to blame for the increased suicide risk, especially in teen and young adult brains.

Authorities in Britain late last year all but banned the use of antidepressants called selective serotonin reuptake inhibitors in children after a review called into question the safety and effectiveness of the drugs in youth.

In the United States, the Food and Drug Administration has ordered the labels of 10 of the inhibitors to carry new warnings about possible adverse behavior changes, including increased anxiety, impulsiveness or aggression.

The FDA says there's no evidence that the drugs cause suicidal behavior in children, but it is re-evaluating drug-company studies to see if a credible link might be established. Congressional investigators also are reviewing the scientific evidence. They are looking at charges from industry critics that scientific studies by drug companies that might reveal danger from the serotonin drugs to young people have been suppressed -- charges the companies deny.

The JAMA study, carried out by Dr. Hershel Jick and colleagues at Boston University, didn't just look at serotonin drugs, but also at two older drugs in a class called tricyclics, that act on a different pathway. And the researchers found there was little difference in the risk for the serotonin regulators Paxil and Prozac and the other drugs.

"The fact that antidepressant prescription is strongly linked to suicidal behavior is well-known," said Dr. Simon Wessely of the Institute of Psychiatry in London. He wrote an editorial on the study with colleague Robert Kerwin. "This simply means that antidepressants are being prescribed for the right indication and that they do not immediately eliminate suicide risk."

Jick and his colleagues said they think "the most likely explanation for this finding is that antidepressant treatment may not be immediately effective, so there is a higher risk of suicidal behavior (suicide attempts or regular thoughts of suicide) in patients newly diagnosed and treated than in those who have been treated for a longer time."

While there was some indication that Paxil might be more dangerous, the researchers noted that doctors might simply be more likely to aggressively treat a newly diagnosed patient who has severe depression, and thus a higher suicide risk, with a newer drug, skewing the results.

The study was funded by the Boston Collaborative Drug Surveillance Program, which has received consultation fees from GlaxoSmithKline, the maker of Paxil. Jick and his team said the company played no role in designing the study or had any input into the results or interpretations they presented.

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