Research points to brain abnormalities that may explain SIDS

It’s a new parent’s worst nightmare: sudden infant death syndrome (SIDS), a mysterious, fatal condition in newborns with an unknown cause. A study was published last year in the journal Lancet eBioMedicine provided compelling evidence that a cholinergic enzyme in live infants could be a biomarker and indicate risk of SIDS in a newborn.

Despite three decades of public health efforts, SIDS remains the leading cause of infant death in the US. In 2020, an estimated 1,389 babies died of SIDS. At the time the study was published, parents on social media were understandably breathing a collective sigh of relief and cheer. Some went so far as to say “they found the cure for SIDS.” As The Scientist reported after the buzz faded, the report was somehow taken out of context. A year later, there is still no cure.

But hope is not lost. This week another piece has been added to the worldwide search for a cause and eventual cure or treatment of the syndrome. A separate group of scientists published a paper May 25 in the Journal of Neuropathology & Experimental Neurology, adding to further evidence that SIDS could be the cause of abnormalities in the serotonergic system, which is related to the neurotransmitter serotonin. It is involved in a wide variety of physiological and psychological processes, including mood, sleep and circadian rhythms.

In the study, the researchers collected brain tissue from the San Diego Medical Examiner’s Office from babies who died of SIDS between 2004 and 2011. By examining their brainstem tissue, they found that the serotonin 2AC receptor was altered, indicating irregularities in this system. could make these babies vulnerable to death under certain circumstances.

To find out, the researchers used a radioactive psychedelic compound called 125I-DOI. The drug DOI readily binds to serotonin receptors, including 2AC, and is often used in serotonin research. When people take it, it’s similar to a trippy kind of amphetamine. But in this study, the researchers used a version of DOI labeled with an iodine radioisotope, which makes it radioactive (and therefore unsafe for human consumption) but allowed researchers to monitor its interactions with serotonin receptors. They found that in babies who died of SIDS, this radioactive psychedelic behaved differently from controls.

In an interview with Salon, the paper’s lead researcher, Robin Haynes, Principal Associate in Pathology at Boston Children’s Hospital, explained that serotonin in the lower brain stem as a neurotransmitter is also critical to breathing and autonomic function. Haynes gave an example of how one of serotonin’s most important functions is the “living protective reflexes.”

“The bottom line is that cot death babies do have abnormalities”

“Let’s say a baby is lying face down in a pillow in a prone position. They start breathing air again, and so their oxygen levels get low, and there are protective processes that babies have that will arouse them,” Haynes said . “They go through a process called autoresuscitation, which triggers breathing. It leads to a sob and that triggers breathing, and those are normal processes, and serotonin is important to these processes.”

What Haynes and her colleagues found is that the 2AC receptor – which previous animal studies had shown to be an important receptor in the autoresuscitation process – was at abnormal levels. Haynes said the serotonin receptors interact with the acetylcholine system, which is what the researchers focused on in the 2022 eBioMedicine study. Acetylcholine is a neurotransmitter involved in many functions, including muscle movement and heart rate. However, how serotonin and acetylcholine are linked to SIDS remains unclear.

“I think the bottom line is that SIDS babies have abnormalities. We always talk about SIDS being heterogeneous in nature, meaning there are different pathologies that contribute,” Haynes said. “So neurotransmitters are one possible pathology. Serotonin is one of them, which we just focus on. Genetics is another aspect.”

Haynes said she considers the search for the cause of SIDS a piece of cake. “Hopefully we can identify more and more of these pieces of the pie to get a full picture of the heterogeneous nature of SIDS,” she said.

Meanwhile, Haynes and her colleagues advise that safe sleeping practices — such as putting a baby to sleep on their back, in a crib with no pillows, blankets or loose clothing — should be implemented to protect babies from SIDS. As mentioned earlier, the American Academy of Pediatrics (AAP) has said for the past 30 years that babies sleeping on their backs are the safest way to sleep. Since the start of the Back-to-Sleep campaign in 1994, SIDS have fallen by more than 50 percent. But it is also flat.

With only a few short weeks or months for new moms to find out how babies sleep before parental leave ends, an unregulated industry of baby sleep experts selling false promises to improve babies’ sleep has sprung up.

“Everyone has been taught, put them on their backs, breastfeed, don’t smoke cigarettes, keep them in your room, things like that, which have been shown to be beneficial, and yet no progress has been made in the past 22 years.” in reducing the number of deaths,” Dr. Harvey Karp, a pediatrician and founder and CEO of Happiest Baby, told Salon in a January interview. The CDC estimates that there are 3,500 sleep-related deaths among infants each year, including SIDS.

“3,500 babies a year, which is a rough equation, that’s the number of innocent Americans who died in 9/11, which was a national catastrophe. And it happens every year,” Karp said. In April, the Snoo, a rocking cradle that holds babies on their backs that Karp created, received approval from the Food and Drug Administration (FDA) as a medical device, the first step in making it covered by insurance.


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“The problem here is that this is the first time the FDA has said that Snoo is safe and effective for holding babies on their backs,” Karp told Salon. “Now we have a way to do that.”

However, without a Snoo, many sleep-deprived parents turn to co-sleeping with their babies when they are extremely sleep-deprived, as Salon previously reported. With only a few short weeks or months for new moms to find out how babies sleep before parental leave ends, an unregulated industry of baby sleep experts selling false promises to improve babies’ sleep has sprung up. Failure to do so can give parents the opportunity to participate in unsafe sleep practices.

Haynes said the fact that SIDS cases have leveled off despite an increase in babies sleeping on their backs tells researchers there is more to learn about the cause of SIDS.

“The more we learn, the more we can put together and ask the right questions. But in terms of safe sleep, where we are right now is that SIDS babies have a biological abnormality that makes them vulnerable to death when they’re in an unsafe sleeping position,” Haynes said. “Because we can’t identify as such, parents should always follow safe sleep practices. It’s so important.”

Haynes added that while the biological components are beyond parents’ control, the sleep environment is under their control.

“I think we all recognize how hard it is to be a new parent,” Haynes said. “What goes into parental control is how you bed share and how you choose to do it. I’m not an expert on bed sharing, but epidemiological evidence shows alcohol consumption, smoking – those can increase the risk. “

While this research is compelling, the study authors note that abnormalities in other parts of the brain unrelated to serotonin have also been implicated in SIDS, highlighting the need for further research. “To date, however, the most robust and reproducible findings in SIDS have been in components of the[serotonone]system,” they write, adding recommendations to use other radioactive drugs such as 125I-DOI to identify the source of this frightening syndrome. light up.

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