A team of researchers funded by the National Institute of
Child Health and Human Development (NICHD) has found that
infants who died of Sudden Infant Death Syndrome (SIDS) have
abnormalities in several parts of the brainstem. The
researchers presented their work at the joint meeting of the Pediatric Academic Societies and American Academy of
Pediatrics societies in the late spring and in a report published in the "Journal of Neuropathology and Experimental
Neurology": Volume 59, Number 5, 2000, pp. 377-384.
The finding builds upon the results of an earlier study that
found abnormalities in the brain region known as the arcuate
nucleus in children who died of SIDS.
"These findings show that SIDS infants have a more global
biological deficit than we previously believed--one that may
originate early in fetal life," said Dr. Marian Willinger,
of NICHD's Pregnancy and Perinatology Branch.
The findings were presented by the senior author of the study,
Dr. Hannah Kinney and a researcher at Children's Hospital and
Harvard Medical School in Boston.
The researchers found that structures in the brainstem of
SIDS infants were less likely to bind to the neurotransmitter
serotonin than were the brains of infant who had died of other
causes. Neurotransmitters are molecules that brain and nerve
cells use to communicate. These molecules are produced in
brain and nerve cells and bind to special receptor molecules
on neighboring cells, in much the same way a key fits into a
Serotonin is found throughout the brain. Specifically, the
SIDS victims in the study were found to have decreased binding
of serotonin in the nucleus raphé obscurus, a brain structure
that is linked to the arcuate nucleus, as well as in four
other brain regions. These brain regions are thought to play a
crucial role in regulating breathing, heart beat, and body
temperature, and arousal. The brain structures have their
origin in a part of the rhombic lip, a region of the
developing embryo that later gives rise to key structures in
the brain stem.