Autism and antidepressants

What are the reasons for the more than six-fold increase in reported cases of autism in the past 20 years? Changes in diagnostic criteria are thought to account for up to 25% of the increased number of cases. Increased awareness of the condition may also mean that more autistic children are being diagnosed as having the condition; some of these children that might have been missed in the past. And there is some evidence that parents of advanced age are more likely to have an autistic child, accounting for some of the cases. Finally, some parents continue to believe (against an overwhelming body of scientific literature) that autism may be caused by something related to childhood vaccinations, and so they refuse to have their children vaccinated. It’s as if lacking an adequate explanation, they’d rather clutch at straws rather than admit that we just don’t know yet.

Two recent studies suggest that some cases of autism may (and I stress may) be related to the mother’s use of certain antidepressant medications during pregnancy. The most recent study is out of Sweden, where national health statistics make large population studies feasible.

The results should be interpreted with caution, however. It will prove difficult to separate out whether it’s the mother’s clinical depression itself, or the drugs used to treat it, that may be increasing the risk of autism. After all, women generally don’t take antidepressants unless they’re clinically depressed. It will be some time before we have a definitive answer, if ever. In the meantime, women who are clinically depressed should discuss the risks and benefits of antidepressant drugs with their physician if they anticipate becoming pregnant.

One final note: the use of antidepressants can’t account for much of the overall rise of autism, because so few pregnant women actually need and use antidepressants. The Swedish study points out that although any woman who uses antidepressants during pregnancy may be doubling the risk of autism in her child, the use of antidepressants during pregnancy probably accounts for less than 1% of all cases of autism in the whole population.