SIDS Linked to Low Levels of Serotonin
The brains of infants who die of sudden infant death syndrome (SIDS) produce low levels of serotonin, a brain chemical that conveys messages between cells and plays a vital role in regulating breathing, heart rate, and sleep, reported researchers funded by the National Institutes of Health.
Akinso: Infants who die from sudden infant death syndrome produce low levels of serotonin in the brain.
Willinger: The neurotransmitter, serotonin, is decreased in the brain stem of the babies who died from SIDS.
Akinso: Dr. Marian Willinger is the Special Assistant for SIDS research at the Eunice Kennedy Shriver National Institute of Child Health and Human Development.
Willinger: In this part of the brain the transmission of nerve impulses takes information from outside sensory information. For example, your temperature, how much carbon dioxide or oxygen that’s in your blood. And then it may tell the body to increase how you breathe or wake up.
Akinso: In a NICHD study, researchers theorize that this newly discovered serotonin abnormality may reduce infants’ capacity to respond to breathing challenges, such as low oxygen levels or high levels of carbon dioxide. Dr. Willinger talks about what these high levels may result from.
Willinger: If a baby's face is covered by bedding they may re-breathe their expired air and that expired air is rich in carbon dioxide and low in oxygen, that is what you breathe out.
Akinso: Researchers analyzed brain tissue from infants who died from SIDS and controls that died of other causes. Included in the analysis were 35 infants who died of SIDS, five infants who died unexpectedly of other causes, and five infants who were hospitalized and died for reasons associated with lack of oxygen.
Willinger: In SIDS babies, they had lower levels of serotonin in about 26 percent lower level, in the brain stem. They also had lower levels of an enzyme called tryptophan hyroxylase, which makes serotonin. So their ability to make serotonin was reduced.
Akinso: Dr. Willinger says the current findings provide important clues to the biological basis of SIDS and may ultimately lead to ways to identify infants most at risk.
Willinger: We may have specific information on deficits in the baby but we need to do a lot more work. We need to understand how low serotonin levels in the brain actually translate to initiating a process that leads to death in these babies.
Akinso: Dr. Willinger hopes that these findings will one day lead to a test that measures infants’ serotonin in the blood or other tissues that reflect brain serotonin levels. For information on SIDS, visit www.nichd.nih.gov. This is Wally Akinso at the National Institutes of Health Bethesda, Maryland.