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  • In a new study, researchers say an enzyme connected to brain arousal could be a biomarker for an elevated risk of Sudden Infant Death Syndrome (SIDS).
  • Experts say the findings are important, but they caution that this was a small study and more research needs to be done.
  • They say babies should sleep on their backs on a firm bedding surface with only one layer of clothing.

Abnormal levels of an enzyme involved in the autonomic nervous system could be a biomarker for elevated risk of Sudden Infant Death Syndrome (SIDS), a new study finds.

Researchers from the SIDS and Sleep Apnoea Research Group at the Children’s Hospital at Westmead in Australia, measured levels of the enzyme Butyrylcholinesterase (BChE) in 67 children who died suddenly and unexpectedly between the ages of 1 week and 104 weeks.

They compared the data to BChE levels in a group of surviving children, matched for age and gender.

The researchers reported that babies whose deaths were classified as SIDS had lower levels of BChE specific activity (BChEsa) than infants whose deaths were not considered SIDS-related as well as those infants who did not die.

“We conclude that a previously unidentified cholinergic deficit, identifiable by abnormal BChEsa, is present at birth in SIDS babies and represents a measurable, specific vulnerability prior to their death,” the researchers reported.

“BChE is one of the enzymes that break down a molecule called Ach, a neurotransmitter that is involved in signaling or sending messages in the nervous system,” Dr. Jenelle Ferry, a neonatologist at Pediatrix Medical Group – Tampa Neonatology, told Healthline. “It’s possible that an abnormality in this pathway could impair the brain’s auto-regulation system and affect brain arousal. The inability to self-arouse is thought to contribute to SIDS.”

“This research does bring into focus the issues of arousal in SIDS and work on biomarkers,” added Dr. Rachel Moon, a University of Virginia School of Medicine researcher specializing in SIDS and the chair of the American Academy of Pediatrics Task Force on SIDS.

However, Moon told Healthline, “As the authors point out, the leading theory of SIDS causation is that multiple factors interact. While everyone would be happy to find one single explanation, it is not so simple.”

Moon particularly took issue with media reports suggesting that the study had uncovered a “cause” of SIDS and that a resulting cure might not be far off.

“This is an extremely small study, with 67 cases and 10 controls,” she said. “The authors themselves call this a ‘potential biomarker.’ There is nothing definitive about this at all. It is definitely not confirmed that this is ‘the cause of SIDS.’”

Moon added that the findings also were too limited to assert that a blood test for BChE could be used to assess SIDS risk.

The cholinergic system has been a key target of SIDS research. Choline is an essential nutrient that gets converted into a neurotransmitter, acetylcholine, involved in muscle contraction, pain response, and brain function.

“BChE levels will never be a true standalone clinical biomarker that can predict SIDS for an individual baby,” asserted Kristina Uban, Ph.D., an assistant professor of public health at the University of California Irvine.However, the present findings are novel and important, as they provide clear evidence that low cholinergic activity is a biological mechanism that contributes to SIDS.”

“This advancement should inform future SIDS research to prioritize any risk factors that may result in low cholinergic activity of the pregnant person and baby, such as low intake of choline-rich foods and exposures to toxins that reduce cholinergic activity, such as alcohol, tobacco, and air pollution,” Uban told Healthline.

Dr. Danelle Fisher, a pediatrician and chair of pediatrics at Providence Saint John’s Health Center in Santa Monica, California, told Healthline that there are several ways that parents can minimize the risk of SIDS.

“Babies should lay on their back during sleep and should only be placed in a prone position with direct supervision, like a parent awake and watching the baby the entire time,” she said.

“Babies should sleep on a firm surface without soft bedding or pillows or toys or blankets. Care should be taken not to overdress the baby. One layer of clothing more than parents feel comfortable in is a good rule to follow,” she added.

“Pacifiers may help prevent SIDS, but they should be used alone, not attached to strings or ropes or toys and not clipped to baby’s clothing,” Fisher noted. “Finally, avoidance of cigarette smoke is important to help prevent SIDS.”