The “old brain” or brain stem where the medulla oblongata resides has been found to have low levels of serotonin in victims of Sudden Infant Death Syndrome (SIDS). In the brain stem, serotonin is a chemical that acts as a neurotransmitter, regulating respiration, heart rate, body temperature, and sleep. [1]
Dr. Marian Willinger, Special Assistant for SIDS research at the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). In this part of the brain stem nerve data concerning outside sensory information, such as core body temperature, blood levels of carbon dioxide (CO2), and oxygen are processed and commands necessary to correct abnormal readings re sent out.
If, for example, the blood oxygen level is low and the CO2 high, nerves leading out from the brain stem will stimulate respiratory centers, causing faster and deeper breathing, raising oxygen and reducing CO2, and, at times, waking the infant.
Research supported by the NICHD suggests that low levels of serotonin in an infant’s brain stem reduces its ability to respond to vital information coming in from the body, such as hypoxemia (low oxygen) and high CO2, indicating respiratory failure.
Dr. Willinger: “If the baby’s face is covered by bedding [rebreathing ] expired air [may occur] […] rich in CO2 and low in oxygen…”
Researchers analyzed brain tissue from 35 infants who died from SIDS and made comparisons with 5 infants who died unexpectedly from other causes and 5 infants who died of hypoxemia in a hospital.
The analysis revealed the brain stem level of serotonin was 26% lower in SIDS infants, with lower levels of tryptophan hydroxylase, the enzyme forming serotonin, found in their brain stems. They had evidence of reduced ability to make serotonin in the region of their brains necessary to respond appropriately to the body’s vital signs.
Dr. Willinger: The current findings shed light on the biological basis of SIDS and may ultimately lead to ways to identify infants most at risk. “…but we need to do a lot more work. We need to understand how low serotonin levels in the brain […] [initiate] a process that leads to death in these babies.”
Dr. Willinger hopes one day a test of an infant’s serotonin level in the blood will be found to reflect brain serotonin levels. SIDS information is available at www.nichd.nih.gov.
Reference:
[1] http://www.nih.gov/news/radio/mar2010/20100319nichdsids.htm
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Very informative article. Thank you.
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