Is there an underlying cause of SIDS?

Research Summary
Meg Guard
Research Assistant

Sudden infant death syndrome (SIDS) is the unexpected death of an infant less than one year of age. SIDS usually occurs during sleep and the cause of death cannot be explained even after a thorough investigation. According to the CDC, SIDS is the leading cause of death in children ages one month to one year in the developed world. Major risk factors for SIDS include adverse sleeping positions and recent illness, such as a cold.

Research into the cause of SIDS has shown that abnormalities in serotonin may cause at least a subset of SIDS cases. Serotonin is a neurotransmitter, or chemical, in the brain with many different roles.

In a recently published study, Dr. Fiona Bright and colleagues compared the brains of infants who died of known causes with the brains of infants who died of SIDS. All the SIDS cases were identified as having at least one risk factor, such as an adverse sleeping position or illness one month prior to death. In addition, the researchers found abnormalities in a part of the brain stem called the raphe nuclei. The brain stem is responsible for controlling key body functions such as breathing and heart rate. The main function of the neurons, or brain cells, in the raphe nuclei is to produce and release serotonin. The researchers found that these serotonin-producing neurons were different (more numerous, higher density, and differently shaped) in SIDS cases compared to non-SIDS cases. The researchers hypothesized that these underlying abnormalities might inhibit infants’ automatic response to potentially life-threatening events during sleep, such as a reduced oxygen supply.

This study supports previous research on the role of serotonin in some SIDS cases. The research supports the possibility of an underlying developmental disorder as an explanation for some SIDS cases. More research is needed, however, on the relationship between SIDS risk factors and the presence of abnormal serotonin neurons during development.

In the future, researchers hope to identify biomarkers for infants who may be at risk of SIDS. A biomarker is an indicator of disease that can be measured in the body. By identifying biomarkers, it is possible that steps could be taken to prevent death in those babies who are at risk of SIDS.

Read more about the research being conducted on serotonin abnormalities and SIDS.