I was probably around 5 when I first learned about Sudden Infant Death Syndrome (SIDS). A friend of the family, one year younger than I, had unusual sleep habits and I brought my new-found knowledge of him to my mother. I almost certainly wanted confirmation that I was the more-grown up with better habits than this friend, as I have been known to be petty and selfish, especially as a kid. My friend lived down the street with his family. Our moms were friends, and my sister and I often played with the three kids, so we naturally competed in a lot of ways. My mom instead told me how this friend, my sister’s playmate, was actually the fourth child born to his family, that the children had lost an older brother, the second child, before he turned one. That because of this mysterious, untreatable, unknowable disease that kills babies was now known to be part of this family, their mom had to fight to keep this youngest child alive. The third child was not affected by SIDS, but the youngest nearly died dozens if not hundreds of times, but was on monitors that would wake his mother up to save his life.

I remember it being one of the scariest things I had ever heard about. My great-grandmother lost a child to cradle death – as it was called in the 1930s – and according to family history, she blamed herself for what she might have done better until the day she died. I know that my mother’s friend, the mother of my friends, still feels guilt and shame for having saved one child but not two from this syndrome in 1985. And my mom told me how, because it comes to sleeping children under a certain age, there are a lot of recommendations about how to hopefully prevent such deaths. Limited blankets, pillows, or stuffed animals in the crib; no soft mattresses; only letting babies sleep on their back. I developed a horror of having my face covered during this time period, because what if I fell asleep and died? I still am uncomfortable sleeping without my nose breathing air beyond the covers, even though I am well beyond the range of SIDS! The Mayo Clinic still lists the sleeping guidelines I learned in the early 1990s as the recommended preventative for SIDS. With the syndrome being sudden and unexplained, there was very little conclusive research expanding beyond the knowledge of the ’80s and ’90s. In 1994, the US ran an education campaign called “Back to Sleep” that did successfully raise awareness of safe sleep practices and SIDS cases dropped by 53%. Even with this wide-spread knowledge, however, SIDS remains the leading cause of mortality for infants under 12 months in age, at a rate of approximately 1 in 1000 births per year. That was the state of things. Research continued, but it seemed like everyone was coming up empty, at least when it came to figuring out either causes or new preventative measures.

At least, it seemed like everyone was coming up empty until this year. An Australian research team (Carmel Harrington, Naz Al Hafid, and Karen Waters, of the SIDS and Sleep Apnoea Research Group of The Children’s Hospital in Westmead, New South Wales) was one of many that were frustrated with the limited information and comfort modern medicine could offer parents.

But many children whose parents took every precaution still died from SIDS. These parents were left with immense guilt, wondering if they could have prevented their baby’s death.

Dr. Carmel Harrington, the lead researcher for the study, was one of these parents. Her son unexpectedly and suddenly died as an infant 29 years ago. In an interview with the Australian Broadcasting Corporation (ABC), Harrington explained what she was told about the cause of her child’s death.

“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.”

Since then, she’s worked to find the cause of SIDS, both for herself and for the medical community as a whole. She went on to explain why this discovery is so important for parents whose babies suffered from SIDS.

“These families can now live with the knowledge that this was not their fault,” she said.

It was already known that there were three factors that caused SIDS: a) environmental (such as the bedding); b) age (between 1 and 12 months of age); and c) biological susceptibility (yet to be determined, but suspected to relate to the body’s ability to wake). The new study, officially published in this June’s Lancet, demonstrates that they have started to crack the code finding a bio marker for those in danger of SIDS. Butyrylcholinesterase (BChE) is an enzyme that appears to be one part of the complex system that is autonomic function, specifically related to waking a sleeping body. In particular, it is one of the enzymes that hydrolyzes Acetylcholine (ACh), the primary neurotransmitter of the parasympathetic nervous system. In testing blood samples from 722 live births collected from 2016-2020 with 67 dead (26 SIDS and 41 non-SIDS), the research indicated that those infants who perished of SIDS showed lowered levels of BChE, while the non-SIDS deaths remained at the same levels as the control group. The blood samples were from the routine “heel prick” or Guthrie Test for a handful of dangerous diseases such as cystic fibrosis and phenylketonuria (PKU). As there is more than one enzyme regulating the ability to wake up, the researchers initially tested for both Acetylcholinesterase (AChE) and BChE, but the storage of samples denatured AChE beyond current ability to test.

Currently, this is as far as this new research has gone. The next stage in SIDS research around the globe will be to develop reliable tests to assess the risk to newborns before children have to die. In the meantime, it’s important to keep following safe sleeping practices for infants who’re at risk. Hopefully in the next decade, SIDS will be join the list of concerns tested with the heel prick!

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