At Columbia, David A. Kahn, MD, clinical professor of psychiatry at the university's medical center, gave a similar response. "There is a small group of patients on the drugs—and I can only guesstimate this at about 10 to 20 percent—who will feel slightly off in terms of trouble with recent recall or finding the right word or remembering a name. It's not their imagination." Some people may also feel sedated or apathetic on many antidepressants, he says, although the newer drugs, which act on multiple neurotransmitters, tend to give people more energy (they still can affect word-finding and memory abilities). "For the most part, the improvement in daily functioning and thinking that comes with treating depression leads to a net gain," Kahn said. "But occasionally the cognitive problems are serious enough to warrant stopping the medication. The point for patients and doctors to be aware of is that it can happen, and if it does, not to scoff at it or dismiss it but to experiment and perhaps switch medications."

Kahn sent over a recent study from a journal called Human Psychopharmacology: Clinical and Experimental on SSRIs and cognitive performance in young patients (their youth—mean age, 32—being important because it ruled out memory loss due to normal aging). The article shows "how equivocal the literature is," he said, "but with a trend toward acknowledging that some people do experience cognitive side effects." The study found that compared with a control group, patients on the drugs showed more memory impairment, including delayed recall; yet the researchers were careful to allow that the results might also be due to the subjects' underlying depression not being fully treated.

After I asked several of the pharmaceutical companies for their take on whether antidepressants cause memory problems or dulling of drive, one spokesperson stated, "The cognitive side effects you reference do not meet the statistical threshold determined by the FDA for inclusion in package literature or patient information." In other words, pharmaceutical companies have no obligation to report or disclose cognitive side effects when there's insufficient data to prove that the drugs cause the symptoms, according to government standards. And he's right, says Susan Cruzan, a media representative at the FDA: A side effect would only be included in patient information if it occurred in at least 5 percent of participants in the trial, and at twice the rate of those in the placebo group. She checked with Thomas Laughren, MD, FDA division director for psychiatric products, who offered this: "The events you are focusing on do not emerge from controlled trials as drug related and that is why they do not get any prominence. In fact, currently used antidepressants are not thought to have cognitive side effects."

The studies required for FDA approval of these drugs, however, generally lasted six to eight weeks, and it often takes much longer for side effects to become apparent. Only recently, for instance, has increased risk of suicide been identified as a possible side effect of antidepressants. In June the FDA put out a public health advisory, noting that several scientific publications have now suggested there is a relationship between taking the drugs and suicidality in adults (the agency has already started requiring manufacturers to add a black box warning for children and adolescents on antidepressants). The FDA announced that it is currently going over hundreds of clinical trials on antidepressants for signs of suicidality, which did not show up in the initial analyses. In the meantime, it warns that adults on these drugs should be watched closely for suicidal thinking or behavior, this being "especially important early in treatment or when the dose is changed, either increased or decreased."