Sudden Infant Death Syndrome May Have a Biological Cause

Researchers may have identified a biological mechanism behind sudden infant death syndrome (SIDS). A better understanding of the causes of the condition could help scientists develop a test that predicts a baby’s risk of SIDS.

SIDS occurs when an apparently healthy baby dies unexpectedly, usually during the first six months of life while sleeping. It is not known why it occurs, but it is believed to include a combination of factors, such as the development of the baby and its environmental exposure, such as cigarette smoking.

To learn more, Robin Haynes of Boston Children’s Hospital, Massachusetts, and colleagues analyzed the brainstems of 70 deceased infants, 58 of whom died of SIDS and 12 of other causes. Among the babies who died of SIDS, the researchers identified differences in the way the neurotransmitter serotonin bound to so-called 5-HT2A/C receptors, which are found in the lower part of the brainstem.

In rodents, these receptors have been linked to protective functions during sleep, such as the ability to respond to low oxygen levels by gasping or waking up.

Among infants who died of SIDS, serotonin binding to 5-HT2A/C receptors was reduced or did not increase as expected as the infants grew older, compared with infants who died of non-steroidal causes. of SIDS, says Haynes. .

These differences may combine with other biological and environmental factors, such as the baby’s sleeping position, to increase the risk of SIDS, the researchers say.

Better understanding the various mechanisms that can lead to SIDS, such as possible genetic abnormalities, could one day help scientists develop a test that predicts a baby’s risk, Haynes says. In the meantime, parents should adhere to safe sleeping protocols, such as placing babies on their backs and keeping blankets off their heads, the researchers say.

“I think one of the things that became clear is that, unlike other things, SIDS is not due to an abnormality in a physiologic system, but rather an interaction,” says Thomas Keens of Children’s Hospital Los Angeles.

The fact that the study found that some of the babies who died of SIDS did not increase in serotonin binding as they aged could explain why these deaths often occur between 2 and 4 months of age, he says, since This is when babies experience rapid changes. changes in your breathing control.