Sudden infant death syndrome, also known as SIDS is a leading cause of infant death. It goes without saying that the death of a baby is a devastating event, and is made even worse when experts are unable to identify any kind of physiological factor that might make babies even more vulnerable.

However, a team of researchers in Australia recently identified a blood biomarker linked to brain arousal that might help identify which infants are the most at risk of SIDS.

Thanks to in-depth research and exploration of SIDS, infant deaths have been significantly reduced as more and more environmental factors that are connected to this terrible event are identified. Even with these improvements, SIDS is still responsible for around 50 percent of all infant deaths in Western countries.

The current understanding suggests that SIDS is a multi-factorial event, which means that it takes many different things to happen at the same time for an infant to perish this way. The best explanation so far is known as the “triple risk model.”

What is the triple risk model?

The triple risk model suggests that three factors have to occur simultaneously for SIDS to take hold: a physiologically vulnerable infant, a critical period of development, and an external stressor. Many external stressors could play a part in SIDS, such as sleeping face down and exposure to tobacco smoke.

“An infant will die of SIDS only if he/she possesses all three factors; the infant’s vulnerability lies latent unless subjected to an exogenous stressor during the critical period,” the researchers write. “Despite intensive research over the past decades, identification of any specific vulnerability has remained elusive.”

The new biomarker

The focus of this new study is an enzyme called butyrylcholinesterase (BChE), which plays a role in the brain’s arousal system. The researchers hypothesized that a deficiency in BChE would make babies more vulnerable to other contributing factors to SIDS.

“Babies have a very powerful mechanism to let us know when they are not happy,” explains lead researcher Carmel Harrington. “Usually, if a baby is confronted with a life-threatening situation, such as difficulty breathing during sleep because they are on their tummies, they will arouse and cry out.”

To gather data, researchers looked at the BChE levels in dried blood spot samples taken from 722 babies at birth. Out of these babies, 67 died suddenly and unexpectedly between the ages of one week and two years, and from these deaths, 26 were classified as SIDS-related.

Compared to the infants who had died of non-SIDS-related causes, and healthy infants from a control group, the SIDS cases demonstrated very low levels of BChE at birth.

“What this research shows is that some babies don’t have this same robust arousal response,” Harrington says. “This has long been thought to be the case, but up to now, we didn’t know what was causing the lack of arousal. Now that we know that BChE is involved we can begin to change the outcome for these babies and makes SIDS a thing of the past.”

Next steps

The researchers will move forward by incorporating BChE testing into standard newborn screening protocols so that parents and doctors alike can implement greater protections against other identified external triggers.

“This discovery has opened up the possibility for intervention and finally gives answers to parents who have lost their children so tragically,” Harrington says.

Source study: eBioMedicine— Butyrlycholinesterase is a potential biomarker for Sudden Infant Death Syndrome