Brain abnormalities linked to SIDS

By Deborah Condon

Abnormalities in the brainstem - the part of the brain that regulates breathing, blood pressure, body heat and arousal - may play a key role in cot death, new research indicates.

Cot death, also known as sudden infant death syndrome (SIDS) refers to the sudden and unexpected death of an infant or young child. The cause of death cannot be found even with a thorough post mortem examination. According to the Irish Sudden Infant Death Association, a child dies as a result of cot death every week in Ireland.

While a number of risk factors have been identified, including putting babies to sleep on their stomachs (babies should be put to sleep lying on their backs) and smoking during pregnancy and around babies, until now, there has been little understanding of SID's biological basis.

However according to researchers at Children's Hospital Boston and Harvard Medical School, new data obtained from autopsies provides the strongest evidence yet that cot death is not a 'mystery' disease, but has a concrete biological basis.

They examined brain autopsy specimens from 31 infants who had died as a result of cot death and 10 who had died from other causes. While examining the lowest part of the brainstem, they found abnormalities in nerve cells that make and use serotonin, which is one of over 100 chemicals in the brain that transmit messages from one cell to another.

The brainstem serotonin system is thought to help coordinate breathing, blood pressure, sensitivity to carbon dioxide and temperature during waking and sleeping. If a baby sleeps face down or has their face covered by bedding, they are thought to re-breathe exhaled carbon dioxide, therefore they are breathing in less oxygen.

Normally, this rise in carbon dioxide activates nerve cells in the brainstem, which in turn stimulate respiratory and arousal centres in the brain so that the baby does not asphyxiate.

"A normal baby will wake up, turn his or her head and start breathing faster when carbon dioxide levels rise", explained one of the lead researchers, Dr Hannah Kinney.

However in babies who die from SIDS, she said, defects in the serotonin system may impair these reflexes.

"We provide strong evidence that SIDS is a biological problem and that the brainstem serotonin system is a good place to focus continued research efforts", added fellow lead researcher, Dr David Paterson.

The researchers believe that the abnormalities they observed begin during early foetal development and maternal behaviours like smoking and drinking alcohol during pregnancy, may adversely affect development of the brainstem serotonin system during this time.

However more research is needed to explain what causes the abnormalities and how they can be prevented.

The researchers are hoping to eventually develop a diagnostic test to identify children at risk of cot death. They also envision a drug or other type of treatment to protect infants who have abnormalities in their brainstem serotonin system.

Details of these findings are published in the Journal of the American Medical Association.

The Irish Sudden Infant Death Association can be contacted at...

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Anonymous - 01/11/2006 18:05

A toxicologist in New Zealand has very interesting information on SIDS. You can read about it at This information can save lives. It has almost eradicated cot death in NZ.

Maria - 02/11/2006 10:47

Hi Anonymous, the link you supplied dosn't work

Zipadee(MEI54455) - 02/11/2006 19:20

There's another "0". works.

Maria - 03/11/2006 09:46

Thanks very much. That's fascinating info - particularly about PVC.

Anon - 06/11/2006 20:10

Thanks for the link. Actually this is not new news! This was established quite some time ago and giving mothers information on mattresses has been considered good practice, also, not re-using mattresses especially second hand ones. It does have some validity and has saved some children. However, it is not the full story. S.I.D.'s can still occur in some babies and we have all heard about adult sid's.

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