If losing a baby to SIDS wasn’t awful enough for new parents, they’ve traditionally been blamed for the tragedy – putting the baby down to sleep improperly, co-sleeping, or allowing “hazards”  like loose blankets or stuffed toys in the crib. But now, a new study published recently in the Journal of the American Medical Association in February of 2010, indicates that the deaths are a biological problem caused by a chemical imbalance in the part of the brain that controls breathing during sleep.

American researchers found that most SIDS babies have a shortage of the neurotransmitter serotonin in their brain stems. Researchers hope their findings will lead to a diagnostic tool that could identify infants at risk of such deaths and then treat them with a serotonin-related drug.

Dr. Hannah Kinney, a Harvard University pathologist and senior study author, cautions that’s not going to happen any time soon and that other neurochemicals may also be playing a role in SIDS deaths. But this could help boost new parents’ confidence in themselves and in co-sleeping.

Serotonin is one of the brain’s key neurotransmitters, allowing a broad range of neurons to communicate with one and other. In the brain stem, it’s a key regulator of breathing, especially during sleep. The researchers speculate that babies with normal brain stem serotonin can turn their heads if something impairs their breathing. “But a SIDS baby has a defect in that [serotonin] circuit and can’t get out of that situation,” says Kinney.

The scientists think the lower serotonin levels may be hereditary and that a number of genes may combine to cut serotonin levels. Risky maternal behavior during pregnancy, such as drinking and smoking, could also play a role in suppressing brain stem serotonin in infants, as could a baby’s exposure to second-hand smoke.

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