Sudden Infant Death Syndrome, the unexpected and unexplained death of a baby under one year of age, is by definition a mystery. But researchers are getting closer to understanding some of the risk factors and mechanisms that contribute to SIDS.
The prevailing theory points to three possible factors: First, the child is at a critical stage of development during the first year of life. Second, the baby is exposed to a stressor, such as sleeping on his stomach, which can reduce the amount of oxygen in the blood and increase the level of carbon dioxide. And third, the baby has an underlying abnormality that makes it harder to survive that traumatic event.
TO study published Thursday in the Journal of Neuropathology & Experimental Neurology points to one such abnormality.
Researchers at Boston Children’s Hospital and Rady Children’s Hospital in San Diego found that a particular brain receptor is likely involved in helping babies wheeze. it was altered in some babies 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 a baby’s sleep and, while rare, is the leading cause of death among babies between one month and one year of age in the US Centers for Disease Control and Prevention attributed nearly 1,400 infant deaths from SIDS in 2020.
To better understand the condition, the researchers behind the new study examined brain tissue from 58 babies who died of SIDS between 2004 and 2011, then compared those samples to brain tissue from 12 babies who died of other causes, such as pneumonia or heart disease. . The results showed that babies who had died of SIDS were more likely to have an altered version of the brain’s serotonin-related receptor than control cases.
Robin Haynes, lead author of the study and a researcher at Boston Children’s Hospital, said that babies normally have a protective response that prompts them to gasp when they don’t get enough oxygen during sleep.
«They wake up and go through what’s called self-resuscitation, where they start to breathe,» he said.
However, with SIDS, that response may not be activated, perhaps due to the altered brain receptor. If a baby can’t restore their breathing and heart rate, that can hinder blood flow and oxygen delivery.
A range of theories about SIDS
The Boston-based research group behind the new study has been investigating the relationship between SIDS and serotonin for roughly three decades, and has published several papers based on various analyzes of the same brain tissue samples.
Those samples are some of the only ones available to SIDS investigators. But that small sample size makes it difficult to draw strong inferences about possible 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, courageous to even try to come to a conclusion,» Otero said.
Still, researchers have long suspected that serotonin plays a role in SIDS given its association with breathing.
«It makes a lot of sense that serotonin should be a key player,» said Dr. Debra Weese-Mayer, division chief of pediatric autonomous medicine at Lurie Children’s Hospital of Chicago. «The question is: Is he the only player?»
Genetics also likely affect a baby’s vulnerability to SIDS, though scientists aren’t sure by what, Weese-Mayer said.
Another factor may be infections babies pick up at a young age, 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. This is also when we see the highest rates of viral infections in babies,» she said.
How parents can reduce their baby’s risk
There are no tests to reveal if a baby has an underlying predisposition to SIDS, and since the causes have not been confirmed, there are no treatments to reduce a baby’s risk. But Haynes said the researchers haven’t given up on that possibility.
«Once a baby with a particular abnormality is identified, the goal is one day to have preventative therapy, but we can’t yet say what that looks like,» he said.
However, there are still ways to protect yourself against SIDS.
the cdc recommends that parents place sleeping babies on their backs at all times. 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 during bedtime, and babies should ideally sleep in the same room as their parents until they are at least 6 months old.
The American Academy of Pediatrics also suggests give babies a pacifier at nap time and at bedtime once they are comfortable nursing.
Breastfeeding has been shown to reduce the risk of SIDS, while using alcohol or tobacco during pregnancy can increase the risk.
«We want people to follow safe sleep guidelines as much as possible,» Caraballo said. «The really scary thing is that it’s possible to do everything right and have the baby still die. At the end of the day, we don’t know the exact cause of death in most cases.»