New research offers clues as to why some babies die of SIDS


Scientists in Australia have found that some babies at risk for Sudden Infant Death Syndrome, or SIDS, have low levels of an enzyme called butyrylcholinesterase (BChE) in their blood. Their study, published May 6 in the journal eBioMedicine, could pave the way for neonatal screening and interventions if the findings are supported by further research.

“This is the first time we have had a potential biomarker for SIDS,” said Dr Carmel Harrington, who led the research at Westmead Children’s Hospital in Sydney, Australia.

Researchers have been trying to narrow down the biological basis of the puzzling syndrome for decades. And although public health campaigns have greatly reduced the incidence of SIDS, it remains one of the leading causes of sudden and unexpected death in infants under the age of 1 in Western countries. In the United States, about 3,400 babies die suddenly and unexpectedly each year, according to the Centers for Disease Control and Prevention. This includes infants who die suddenly from a known cause, such as suffocation, as well as those who die without a clear cause, such as SIDS. Nearly half of sudden and unexpected infant death (SUID) cases in the United States are due to SIDS.

One of the reasons why SIDS remains so tragic and mysterious is that it is probably not caused by a single biological mechanism, but by a combination of factors that come together in a perfect storm, says Dr Thomas Keens , a pediatric pulmonologist at Children’s Hospital Los Anges. Previous studies have found low activity or damage in parts of infant brains that control heart rate, breathing, and sleep arousal, for example, as well as environmental stressors such as poor bedding. fluffy or second-hand smoke.

“The thinking among researchers is that some babies die from SIDS because they don’t wake up in response to a dangerous situation when they’re sleeping,” Dr Keens said.

To test if there was anything fundamentally different about SIDS babies, Dr Harrington and colleagues compared dried blood samples from the newborn heel prick test of 655 healthy babies, 26 dead babies SIDS and 41 babies who died of another cause. They found that about nine out of ten babies who died of SIDS had significantly lower levels of BChE than babies in the other two groups.

“I was just stunned,” said Dr Harrington, who has been searching for clues and crowdfunding for her research for nearly 30 years since losing one of her own children to SIDS. “Parents of SIDS babies carry enormous guilt because their child essentially died on their watch. But what we discovered with this study is that these infants are different from birth, the difference is hidden and no one knew about it before. So it’s not the fault of the parents.

The new findings support researchers’ hypothesis that babies who die of SIDS have problems arousing, said Dr. Richard Goldstein, pediatric palliative care specialist at Boston Children’s Hospital. BChE plays a role in the availability of important neurotransmitters in the brain’s arousal pathway. Low levels of the enzyme could indicate that the brain is not able to send signals telling a baby to wake up and turn their head or catch their breath. “But we need a lot more research before we can understand its real meaning,” Dr. Goldstein said.

Although the study identifies an important chemical marker in a small group of infants, it is too early to tell whether widespread testing for BChE will be helpful.

For one thing, scientists and doctors don’t know what a “normal” level of the enzyme looks like. And because the Australian researchers didn’t have access to fresh blood samples for BChE, they didn’t measure absolute levels of the enzyme. There was also an overlap between the infants. Some of the babies who died from SIDS had BChE levels in the same range as the babies who did not die.

“If you’re going to test every baby that’s born, you want the results to come out as abnormal only for very high-risk babies,” Dr Keens said. Even if further studies helped refine the BChE test to accurately distinguish between babies who might die of SIDS and those who might go on to live healthy lives, doctors and parents would still be faced with a dilemma: what to do next. ? Currently, there is no intervention or treatment for low levels of BChE.

Much of the advice for preventing SIDS remains the same, Dr. Keens said. Be sure to follow safe sleep recommendations, such as laying your baby on her back, both at nap time and at night. Remove sheets, blankets, pillows, pillows, and stuffed animals from your baby’s sleeping area. And consider keeping your baby in the same room as you at night for at least six months, or ideally until your baby is a year old.

The American Academy of Pediatrics also recommends avoiding exposure to smoke, alcohol, and street drugs during pregnancy; breastfeeding; vaccinate regularly; and using a pacifier to reduce the risk of SIDS.


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