Sudden infant death syndrome (SIDS) remains a perplexing phenomenon where apparently healthy infants inexplicably pass away before their first birthday, typically while they are asleep. Although it is rare, SIDS is currently the leading cause of post-neonatal infant mortality in the United States, affecting approximately 103 out of 100,000 live births each year. Despite national public health campaigns in the 1990s promoting safe sleep environments and better sleep positions for infants, the rates of SIDS cases have remained stagnant over the past three decades.
In a recent study, researchers collected tissue samples from infant deaths that occurred between 2004 and 2011 at the San Diego Medical Examiner’s Office. They focused on examining the brain stems of 70 infants who tragically passed away during that period and conducted tests to identify any consistent abnormalities.
Their findings indicate that sudden infant death cases exhibit alterations in the serotonin 2A/C receptor when compared to control cases of infant deaths. Previous research conducted on rodents revealed that signaling through the 2A/C receptor contributes to arousal and autoresuscitation, safeguarding the brain’s oxygen supply during sleep. This new research suggests that certain infants may possess a biological abnormality that renders them vulnerable to death under specific circumstances.
The investigators propose that SIDS occurs when three factors coincide: an infant is in a critical stage of cardiorespiratory development during their first year, the infant is exposed to external stressors like a prone sleep position or bed-sharing, and the infant possesses a biological abnormality that makes them susceptible to respiratory challenges while sleeping.
Lead author of the study, Robin Haynes, emphasizes the significance of their work, stating, “The work presented builds upon previous research by our laboratory and others, which has demonstrated abnormalities in the serotonergic system of some SIDS infants.” However, Haynes also notes that while abnormalities in the serotonin 2A/C receptor have been identified in SIDS cases, the precise relationship between these abnormalities and the cause of death remains unknown. Further research is necessary to understand the consequences of these receptor abnormalities within the broader network of serotonin and non-serotonin receptors that protect vital functions in cardiac and respiratory control when faced with challenges. Currently, there are no means to identify infants with biological abnormalities in the serotonergic system, underscoring the continued importance of adhering to safe sleep practices.
The paper titled “Altered 5-HT2A/C receptor binding in the medulla oblongata in the sudden infant death syndrome (SIDS): part I. Tissue-based evidence for serotonin receptor signaling abnormalities in cardiorespiratory- and arousal-related circuits” will be accessible starting May 25th at midnight via the following link: https://doi.org/10.1093/jnen/nlad030.