(the brainstem appears to be the area of the brain most affected by
premature umbilical cord clamping)

http://www.scrippsnews.com/node/15681

Link found between serotonin and SIDS

By LEE BOWMAN
Tuesday, October 31, 2006

Infants who die from sudden infant death syndrome have abnormalities
in a part of the brain that helps control breathing and arousal and
are not merely random victims of suffocation, researchers report
Wednesday.

The scientists hope that the findings, published in The Journal of
the American Medical Association, will allow them to develop a
diagnostic test to determine which babies are most at risk from
SIDS, the leading cause of death in American infants after the
newborn period.

Dr. Hannah Kinney and David Paterson, a neuroscientist, both of
Children's Hospital in Boston, say the infants who died from SIDS
had significantly more cells that make and release the chemical
messenger serotonin in their brainstems than did the brains of a
control group of infants who died from other causes.

While serotonin is best known for its role in regulating mood, in
the brainstem it is thought to help coordinate breathing, blood
pressure, sensitivity to carbon dioxide and temperature during
waking and sleep.

The researchers studied brain tissue samples from 31 infants who
died of SIDS and 10 who died of other causes in San Diego between
1997 and 2005. The samples were provided from autopsies conducted
by the San Diego Medical Examiner's office.

Although the brainstem tissue from SIDS infants had more
serotonin-producing cells than did the control samples, they had
fewer receptors for the chemical and about the same amounts of a
protein that helps recycle serotonin back into the cells.

Kinney had earlier documented serotonin receptor abnormalities in
two other groups of SIDS infants, but had been unable to determine
the extent of the defects or how great a role they played in causing
babies to stop breathing. Studies also suggested that babies who
stirred less during the night were more at risk.

"These findings provide evidence that SIDS is not a mystery, but a
disorder that we can investigate with scientific methods and, some
day, may be able to identify and treat, Kinney said.

Normally, when babies sleep face down, or have their faces covered
by bedding, they are thought to re-breathe exhaled carbon dioxide.
But this rise in carbon dioxide activates the nerve cells in the
brainstem, which then stimulates breathing and arousal centers in
the brain so the baby doesn't suffocate.

"A normal baby will wake up, turn over and start breathing faster
when carbon dioxide levels rise," Kinney said. But in babies who
die from SIDS, the defects in the serotonin system may impair those
reflexes, the researchers suggest.

The researchers note that despite a 12-year national public health
campaign encouraging parents to place babies on their backs to
sleep, 65 percent of the SIDS infants in the study were found
sleeping on their stomach or side. However, studies also show that
since the campaign began, only about 20 percent of babies typically
sleep on their stomachs and the rate of SIDS deaths has fallen by
about half.

"Back sleeping is an intervention for all babies, but there are
still babies who die of SIDS after being placed on their backs,"'
said Marian Willinger, a SIDS specialist at the National Institute
of Child Health and Human Development who developed the Back to
Sleep campaign. "We still can't target high-risk babies because we
can't identify them."

The study also showed that there is a biological explanation for
why male infants die from SIDS twice as often as females. The male
SIDS victims in the study had significantly fewer serotonin receptors
than did the female SIDS infants.

Paterson and Kinney believe that the brain abnormalities begin early
in fetal development, and suspect that environmental factors, such
as maternal smoking and alcohol use, may negatively impact development
of the brainstem. But they suspect that if infants survive through
the first six months to a year outside the womb, their brains mature
sufficiently to react normally to oxygen deficits.

"Our goal is to find a way _ a diagnostic test _ to identify these
defects in living infants, and then find a way to correct these
defects by drugs or other means as the infant passes through the
first six months of life, the period of greatest risk for SIDS,"
Kinney said.

On the Net: www.jama.com

www.nichd.nih.gov