July 5 (UPI) -- Researchers at Boston Children's Hospital and Harvard Medical School found high levels of serotonin in infants who died from sudden infant death syndrome among those in a recent study.
The study, published in the July edition of Proceedings of the National Academy of Sciences, showed blood samples of infants who died of SIDS had high levels of serotonin, a chemical that carries signals along and between nerves.
Sudden infant death syndrome, or SIDS, refers to the sudden death of an infant under 1-year-old for an unexplained reason after a complete autopsy and investigation.
SIDS is the leading cause of postneonatal infant mortality and its causes have long been a mystery in the medical community.
The researchers found 31 percent of SIDS infants had elevated levels of serotonin in their blood. Previous studies showed multiple serotonin-related brain abnormalities in infants who died of SIDS and a decrease in the levels of serotonin in the brain regions involved in breathing, heart rate patterns, temperature regulation, blood pressure and arousal.
The study, funded in part by the National Institutes of Health, shows that an abnormal level of serotonin metabolism may point to an underlying susceptibility to an increased risk of SIDS.
Researchers say the findings could lead to blood tests that could distinguish between SIDS cases and other causes of death in infants.