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SIDS

SIDS UPDATE

By Rebecca Geiger

Though doctors don't know for certain what causes Sudden Infant Death Syndrome (SIDS), the sudden unexplained death of an infant under age one, they're getting a lot closer thanks to promising new research from around the globe. Compared to a decade ago, "We're much nearer to finding causes and prevention methods," says Robert Hinnen, program director for the SIDS Center of New Jersey. Some of the latest findings that may be linked to SIDS:

Serotonin
Researchers from Yale Medical School led by Dr. George Richerson, associate professor of neurology, have found that neurons in the brain producing the chemical serotonin regulate or detect carbon dioxide levels in the blood. This is significant since babies who succumb to SIDS are thought to be unable to rouse when breathing difficulties arise. "Carbon dioxide in the arteries is the most important factor in getting you to breathe," says Dr. Richerson, "but if there's too much it's fatal."

Richerson and others believe that in SIDS babies the serotonin system -- the mechanism for alerting the brain that there's been a rise in carbon dioxide -- is off-kilter and that the baby can't respond appropriately. "If a baby falls asleep with his face in the mattress, carbon dioxide levels can rise, and though most infants would wake slightly, turn the head, and begin breathing harder, it appears that some SIDS babies don't have this response," says Dr. Richerson.
Bacterial Infection
New research from Dr. Paul Goldwater, clinical microbiologist and infectious diseases physician at the Adelaide Women's and Children's Hospital in Australia indicates that SIDS may be linked to an infection caused by a protein from the common bacterium E. coli. The protein, curlin, produces shock in mice. And, says Dr. Goldwater, there's plenty of evidence of shock in SIDS babies. Though E. coli was found in most of the babies studied, curlin was only in the blood of SIDS babies, but in none of the comparison infants. Dr. Goldwater thinks that the increased SIDS risk for babies that sleep on their stomachs may be because they're exposed to more E. coli, taking it in through their mouths from exposure to contaminated surfaces.

Other experts find the E. coli theory intriguing, but point out that more research should be done. They say babies infected with the bacteria would likely have shown symptoms before death, and that E. coli could have been introduced post mortem.
Genetics
Scientists from Scotland are in the preliminary stages of genetic research. They are looking for a particular form of a gene that when present could affect the brain's ability to handle environmental stressors such as infection or overheating.

For now, most experts point to the Triple Risk Model when explaining SIDS, saying that there are likely multiple factors involved such as:

The baby is in the first six months of life -- a very critical period of development
The infant is born with a specific defect, such as brain or genetic abnormality.
The defect is triggered by an outside stressor: sleeping prone, smoke, an overheated room, fever, or infection.

The future looks bright for overcoming SIDS. Once doctors pinpoint causes, they hope to develop methods that include drug and vaccine treatments, as well as being better able to detect abnormalities and monitor at-risk infants.

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