Sudden Infant Death Syndrome (SIDS) is one of the leading causes of infant death, and researchers have so far been unable to identify a specific physiological factor that can make a baby more vulnerable. A team of researchers in Australia has already identified a blood biomarker associated with brain arousal that could potentially be used to identify babies at greatest risk for SIDS.
In the last few years, SIDS infant deaths have been significantly reduced as researchers have identified more and more environmental factors that play a role in this terrifyingly unpredictable event. But despite this progress, SIDS still accounts for about 50 percent of all infant deaths in Western countries.
SIDS is considered to be a multifactorial event, which means that several factors are needed to occur simultaneously in order to strike a baby. The current hypothesis for explaining SIDS is known as the “triple risk model”.
This model suggests that three factors must come together at the same time for SIDS to occur: a physiologically vulnerable baby, a critical period of development, and external stress. Researchers have identified several external stressors that contribute to the risk of SIDS, from sleeping face down to exposure to tobacco smoke.
“A baby will die of SIDS only if it has all three factors; The baby’s vulnerability is latent unless it is subjected to exogenous stress during the critical period, the researchers wrote in the new study. “Despite intensive research in recent decades, the identification of each specific vulnerability remains elusive.”
The new study focuses on a specific enzyme called butyrlicholinesterase (BChE). This enzyme plays a role in the excitation system of the brain, and researchers have suggested that BChE deficiency may make the baby more vulnerable to other factors that contribute to SIDS.
“Babies have a very powerful mechanism to let us know when they are unhappy,” said Carmel Harrington, the project’s lead researcher. “Usually, if a baby is faced with a life-threatening situation, such as difficulty breathing during sleep because he is on his stomach, he will wake up and cry.
The researchers looked at BChE levels in dried blood samples taken from 722 babies at birth. Of the cohort, 67 babies died suddenly and unexpectedly at the age of one to two years. Of the deaths, 26 were classified as SIDS-related and 41 as non-SIDS.
Compared with infants dying from other causes and the control group of healthy infants, cases of SIDS showed significantly low BChE levels at birth. According to Harrington, this shows that low levels of the enzyme for brain excitation can make the baby more vulnerable to SIDS.
“What this study shows is that some babies don’t have the same strong arousal response,” Harrington said. “It was thought for a long time, but so far we didn’t know what caused the lack of excitement. Now that we know BChE is involved, we can start changing the outcome for these babies and making SIDS something of the past. “
Moving forward, researchers are calling for more work to confirm their findings. As this is the first measurable blood biomarker that can be used to indicate the risk of SIDS, the aim would be to include BChE testing in standard neonatal screening protocols. This can allow parents and doctors to identify babies at high risk for SIDS and include greater protection against known external factors.
Harrington also hopes to begin work on ways to address this particular enzyme deficiency so that babies found with low BChE levels can be further protected.
“This discovery opened up the possibility of intervention and finally provides answers to parents who have lost their children so tragically,” Harrington concluded.
The new study is published in the journal eBioMedicine.