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:
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
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.
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
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.
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