Sudden infant death syndrome, the unexpected and unexplained death of an infant younger than one year old, is by definition a mystery. But researchers are getting closer to understanding some of the risk factors and mechanisms that contribute to SIDS.
Existing theory points to three possible reasons: First, the baby is at a critical stage of development in the first year of life. Second, the baby is exposed to a stressor, such as sleeping on their back, which can lower the amount of oxygen in their blood while increasing the level of carbon dioxide. And third, the baby has an underlying abnormality that makes it difficult to survive that traumatic event.
A study published Thursday in the Journal of Neuropathology & Experimental Neurology points to one such abnormality.
Researchers from Boston Children’s Hospital and Rady Children’s Hospital in San Diego discovered that a specific brain receptor is likely involved in helping babies breathe air. was altered in some infants who died of SIDS. The receptor in question is part of the serotonin system, which plays an important role in regulating involuntary bodily functions such as heart rate, breathing and blood pressure.
SIDS usually occurs during an infant’s sleep, and although it is rare, it is the leading cause of death in infants between one month and one year of age in the US The Centers for Disease Control and Prevention attributed nearly 1,400 babies died of SIDS in 2020.
To better understand the condition, the researchers behind the new study analyzed brain tissue from 58 infants who died of SIDS between 2004 and 2011, then compared those samples to the brain tissue of 12 babies died of other causes, such as pneumonia or heart disease. . The results showed that infants who died of SIDS were more likely to have an altered version of the serotonin-related brain receptor than control cases.
Robin Haynes, the lead author of the study and a researcher at Boston Children’s Hospital, said that babies usually have a protective response that prompts them to gasp for air when they are not getting enough oxygen. while sleeping.
“They wake up and they go through what’s called auto-resuscitation, where it starts breathing,” he said.
In SIDS, however, that response may not start, perhaps because of altered brain receptors. If a baby can’t get their breathing and heartbeat back, it can block blood flow and oxygen supply.
A range of theories about SIDS
The Boston-based research team behind the new study has been investigating the link between SIDS and serotonin for nearly three decades, and has published multiple papers based on different analyzes of the same tissue samples. of the brain.
Those samples are just a few of those available to SIDS researchers. But the small sample size makes it difficult to draw strong inferences about potential causes or risk factors, according to Dr. José Javier Otero, director of neuropathology at The Ohio State University College of Medicine.
“It’s almost, from a scientific point of view, brave to try to try to draw a conclusion,” Otero said.
However, researchers have long suspected that serotonin plays some role in SIDS because of its relationship with breathing.
“It makes perfect sense that serotonin should be a major player,” said Dr. Debra Weese-Mayer, chief of the pediatric autonomic medicine division at Lurie Children’s Hospital of Chicago. “The question is: Is this the only player?”
It’s likely that genetics also affects a baby’s vulnerability to SIDS, though scientists aren’t sure in what capacity, Weese-Mayer said.
Another factor may be infections that babies get early in life, according to Dr. Michelle Caraballo, a pediatric pulmonologist at Children’s Health in North Texas and an assistant professor at UT Southwestern.
“SIDS rates are highest in the winter. That’s also when we see the highest rates of viral infections in babies,” she said.
How parents can reduce their baby’s risk
No tests exist to show whether a baby has an underlying predisposition to SIDS — and because there are no confirmed causes, there are no treatments to lower a baby’s risk. But Haynes said the researchers haven’t given up on that prospect.
“Once you identify a baby with a particular abnormality, the goal one day is to have preventative therapy, but what that looks like we can’t say yet,” he said.
However, there are still ways to protect against SIDS.
The CDC recommending that parents put sleeping babies on their backs all the time. A baby’s sleeping area should be firm, flat and free of soft toys and bedding such as blankets, pillows and bumper pads. Parents should not cover their baby’s head at bedtime, and babies should sleep in the same room as their parents until they are at least 6 months old.
Also the American Academy of Pediatrics suggesting giving babies a pacifier at bedtime and bedtime when they are comfortable breastfeeding.
Breastfeeding has been shown to reduce the risk of SIDS, while using alcohol or tobacco while pregnant can increase the risk.
“We want people to follow safe sleep guidelines as much as possible,” Caraballo said. “What’s really scary is that it’s possible to do everything right and the baby will still die. At the end of the day, we don’t know the exact cause of death in most cases.”
