How often do antidepressants make people suicidal?

NEW YORK (Reuters Health) – Antidepressants rarely trigger suicidal thoughts or behaviors, suggests a new study of more than 140,000 patients in European psychiatric hospitals.

But experts worry that some suicidal thoughts or behaviors might have been written off as part of the patient’s illness, or that some cases of patients feeling or acting suicidal might have been missed altogether.

According to the Centers for Disease Control andPrevention , antidepressants are one of the most commonly prescribed drug classes in the U.S. One study found that 10 percent of the U.S. population was taking these medications in 2005.

The authors of the current study, led by Dr. Susanne Stubner of Ludwig-Maximilian University in Munich, Germany, analyzed medical reports from a drug surveillance program covering more than 300,000 patients treated in psychiatric hospitals in Germany, Austria and Switzerland between 1993 and 2008. The data included 142,090 adult patients, who were taking at least one antidepressant, most commonly mirtazapine or venlafaxine.

Of those on antidepressants during the 15-year study period, there were 33 patients who had thoughts of wanting to commit suicide that doctors judged to be “possibly” or “probably” related to the drug. Eighteen of these patients tried to commit suicide and three more completed suicides.

Just over half of the suicidal patients were on the class of antidepressant known as selective serotonin reuptake inhibitors (SSRIs), and 45 percent of them were also taking benzodiazepines, a class of tranquilizers that includes Valium.

In the entire study group of patients on antidepressants, 37 percent were taking SSRIs and 32 percent were on benzodiazapines in addition to antidepressants.

Stubner and her colleagues couldn’t catch all cases of drug-related suicidal thoughts or acts because doctors relied on patients’ own reports to determine why they felt or acted suicidal. The researchers also acknowledge that other instances of suicidal behavior were probably missed when doctors weren’t watching.

Still, the finding “supports the assumption that antidepressant drugs rarely trigger suicidality,” the authors write in the study, which is published in the Journal of Clinical Psychiatry. They also emphasize that the study was not intended to prove or disprove a link between the drugs and suicide, but to look at those cases where antidepressants were thought to trigger suicidal thoughts or behaviors to learn more about the possible association.

For example, it’s important for doctors to be aware that patients who were suicidal often became restless or impulsive while taking antidepressants, the authors say.

Experts not involved with the study caution against reading too much into the finding that fewer than 1 in 4,000 patients on antidepressants showed any drug-related suicidal thoughts or behavior.

“This study can only identify the tip of the iceberg,” Dr. Marc Stone, a medical officer at the U.S. Food and Drug

Administration  who has studied the link between antidepressants and suicide, told Reuters Health by email. “Because many patients were hospitalized because they were suicidal or likely to become suicidal, subsequent suicidal thinking or behavior is much more likely to be attributed to the patient’s psychiatric condition rather than the drug even if the drug is, in fact, the cause.”

In addition, Stone said, many patients in the study had likely been on an antidepressant for a long time before they were hospitalized. Most cases of drug-related suicidal thoughts and behavior happen soon after a patient starts taking an antidepressant, he said, so these cases wouldn’t show up in the study.

Dr. David Healy, one of the early researchers to express a concern about the risk of suicide in some patients on SSRIs, agreed that the study likely missed many patients who became suicidal as a result of antidepressants. “It isn’t an estimate of how often this is actually happening, it’s an estimate of how often doctors who are faced with this kind of thing happening recognize a link,” Healy, a psychiatrist at Cardiff University in Wales, told Reuters Health.

The medical community tends to pay more attention to large studies — often funded by the pharmaceutical industry — than to doctors’ own experiences with patients, he said. Because of this, doctors might be discouraged from reporting suicidal tendencies in their patients taking antidepressants if their observations go against scientific research and drug company claims, Healy said.

The European drug surveillance program is funded by many pharmaceutical companies, including those that manufacture antidepressants. In the report, five of the study’s eight authors disclosed receiving grants or consulting fees from drugmakers.

Whether antidepressant drugs trigger any suicidal behavior is not in question, Healy said. “This is a problem that is caused by the drugs,” he said, and the study confirms that the link exists. “The only argument is about how frequently it’s happening,” he said.

SOURCE:Journal of Clinical Psychiatry, online August 10, 2010.