New clue in sudden infant death cases

Dr Carmel Harrington is an Australian lawyer turned sleep scientist. She has also written a couple of books, The Sleep Diet, on how sleep impacts our ability to maintain healthy body weight, and The Complete Guide to a Good Night’s Sleep. Harrington is also an honorary research fellow at Sydney Children’s Hospital. Decades ago, her seemingly healthy baby boy, Damien, died suddenly and without warning.

When a friend experienced the same heartbreak a few years later, Harrington went back to university determined to try to solve the mystery of Sids – sudden infant death syndrome – which affects 40-60 babies a year in New Zealand.

Harrington and her colleagues have just published the results of a small study that suggests many babies at risk of Sids could be identified just days after they are born. We breath unconsciously. The action is regulated by our autonomic nervous system. Harrington and colleagues hypothesised that levels of an enzyme called butyrylcholinesterase could be a marker for potential autonomic nervous system problems. To test this, they went through records looking for children under 2 who had died in New South Wales between July 2018 and July 2020. They found 26 babies classified as having died of Sids and 30 who died of other causes. They then matched each baby with nine to 10 living children born the same day.

Next, they measured butyrylcholinesterase levels in blood samples taken from each child. When babies are about 2 days old, one of their heels is pricked and a tiny bit of blood smeared onto a bit of card. The dried blood spot is then screened for more than 20 rare conditions that can make babies sick. The team found that butyrylcholinesterase levels were lower in babies who subsequently died of Sids compared to the healthy controls and babies who died of other causes.

This strongly suggests that at least some Sids cases are caused by problems with a baby’s autonomic nervous system and that this vulnerability is present at birth and can be screened for. It also suggests new avenues for trying to find preventive treatments for Sids.

What is depressing is that in 2018 Harrington had to launch a crowdfunding campaign to access the equipment she needed to do the study.With too little money in the research funding system, competition is fierce, and many excellent people and projects struggle to get funded. Harrington is a good example of the lengths some researchers must go to get important research done.