A new opinion article, published in the journal Trends in Neuroscience, discusses the possible underlying causes between two poorly understood conditions that lead to sudden, unexplained deaths: sudden infant death syndrome (SIDS) and sudden unexpected death in epilepsy (SUDEP).
No one knows why sudden death cases occur but the paper’s author, Gordon Buchanan, argues that the similarities between these two conditions appear to suggest a similar neurological cause.
These mysterious syndromes seem to occur when a baby, or adult, goes to sleep and doesn't wake up. One of the biggest questions is if this is down to someone's airway being blocked while sleeping, for example, by a pillow, why are they not waking up to help themselves, or crying out? Buchanan suggests a fault in this internal carbon dioxide "alarm system" may be a shared cause of SIDS and SUDEP.
In the article, he suggests, based on his and his team's research, that the focus of future study should be on how the brain alerts us that we are not getting enough oxygen.
“Our studies suggest there is a direct mechanism by which carbon dioxide can cause arousal from sleep," Buchanan, who is an associate professor of neurology at the University of Iowa, said in a statement. "In particular, we have evidence that suggests serotonin neurons in the midbrain are directly activated by carbon dioxide and cause arousal without altering breathing.”
A failure of this mechanism could lead to the person in question not waking up and their eventual death by asphyxiation. SIDS claims the lives of over 1,500 babies every year in the US, so putting precautions in place, like making sure a child's mouth and nose are free of obstructions at night by removing soft pillows and bedding, using tight clothing, and reducing co-sleeping are suggested.
SUDEP is responsible for the deaths of 3,500 people every year and it also tends to happen at night. The researchers consider this an underappreciated factor, so similar precautions should be considered for people suffering from epilepsy, like sleeping on their back and using technologies that can measure their breathing and alert others.
“One of the biggest changes the research has prompted is the recognition that we should be monitoring breathing in epilepsy monitoring units. That is a major paradigm shift,” Buchanan said.
While steps have been made in understanding the conditions, there are still many unknowns both in terms of underlying causes and in terms of the wider spectrum of sudden deaths. Is it possible that all the unexpected and unexplained fatalities have common causes and they all sit on the continuum?
The researchers are investigating possible biomarkers shared by the conditions and they are also interested in anatomical and physiological changes in the brains of adults who died from SUDEP and babies who died from SIDS. However, as the road to understanding these syndromes is still rife with uncertainties, preventative measures by at-risk people (parents of young infants, epilepsy sufferers) remain the best way forward.