Smell test may detect autism

A 10-minute test could help doctors sniff out autism, a new study contends.

Whether smelling roses or sour milk, children with autism inhale about the same amount of air, researchers report July 2 in Current Biology. In contrast, kids without the disorder breathe in pleasant scents more deeply than stinky ones.

The findings hint that a whiff-and-sniff test could one day offer a quick and easy way to determine whether a child has autism. But the study was small, and other researchers are not convinced.

“It’s a good idea,” says Neil Martin, a psychologist at Regent’s University London who studies the sense of smell. But “you can’t draw any conclusions from this study yet.”

Neuroanatomist Johannes Frasnelli of the University of Quebec at Trois-Rivières in Canada says that the study’s authors “have a really sexy story to sell.”  But the work has a long way to go before it’s ready for clinical use, he says.

Researchers have previously tried to forge a link between autism and the sense of smell, but results are all over the map, says study coauthor Liron Rozenkrantz, a neurobiologist at the Weizmann Institute of Science in Rehovot, Israel.

Reliance on written or verbal instructions could be muddling the picture. Autistic kids might not understand what researchers are asking, Rozenkrantz says. So she and colleagues sidestepped the problem by hooking kids up to an odor-dispensing device that automatically measures the depth and length of a sniff.

Over 10 minutes, the researchers delivered 20 odor pulses (shampoo, roses, sour milk or rotten fish) to the noses of 18 autistic children and 18 typically developing children. Kids without autism inhaled good smells more deeply than gross ones, while kids with the disorder didn’t adjust their sniffs.

Rozenkrantz cautions that the test still needs more work. “We are very far from claiming we have a diagnostic tool,” she says. “What we have now is a proof of concept.”

Martin disagrees. The study didn’t examine nearly enough kids, he says. And the researchers didn’t check whether the children could even smell in the first place.