A marker that could help identify babies at a higher risk of sudden infant death syndrome (SIDS) has been discovered by Sydney researchers.
The study conducted by The Children's Hospital Westmead confirmed what had long been suspected — that SIDS victims were unable to wake themselves up — but it went one step further by providing the why.
The enzyme butyrylcholinesterase (BChE) plays a major role in the "brain's arousal pathway" and was found at "significantly lower" levels in babies who die of SIDS.
"Babies have a very powerful mechanism to let us know when they are not happy," Lead researcher and Honorary Research Fellow Dr Carmel Harrington said.
"Usually, if a baby is confronted with a life-threatening situation, such as difficulty breathing during sleep because they're on their tummies, they will arouse and cry out.
"What this research shows is that some babies don't have this same robust arousal response.
"Now that we know that BChE is involved, we can begin to change the outcome for these babies and make SIDS a thing of the past."
Public health campaigns focusing on safe sleeping, overheating and maternal smoking during a baby's first three months have reduced the incidence of SIDS.
However, the children's hospital says death rates remain high.
"There is this perception that SIDS isn't a problem anymore or that the problem can be solved if all babies had the correct sleep conditions, but two children still die from SIDS in Australia every week," said Professor Karen Waters, the head of the children's hospital SIDS and Sleep Apnoea Research Group.
It is hoped the finding could lead to the development of a screening test in a few years' time.
Hailed as a "game-changer" to "every parent's worst nightmare", the discovery of BChE also provides answers to parents, like Dr Harrington, whose healthy babies died "on their watch".
"My son, Damien, died suddenly and unexpectedly one night. It took me about two years before I could really take a breath again, and at that point, I thought I actually want to find out why he died.
"Nobody could tell me. They just said it's a tragedy. But it was a tragedy that didn't sit well with my scientific brain."
That was 29 years ago.
Since then, Dr Harrington has dedicated her life to finding answers and funding, which has also involved setting up the crowdfunding campaign Damien's Legacy in honour of her "beautiful little boy".
The study, published in The Lancet, analysed dried blood spots taken as part of the Newborn Screening Program.
The blood was analysed after deaths from SIDS and other causes, and each one was compared to 10 surviving infants.
Attention will now focus on using the findings to develop targeted interventions.
"This is the gift that I feel I got for Mother's Day because the timing of this is really peculiar to me, that it's coming on Mother's Day," Dr Harrington said.
"This gives us a focus for our future research. So there's quite a lot to be done. We need to understand the system better … We know what we have to do. It's just actually getting the funding for it."
