Is Sudden Infant Death Linked to Cholinergic Dysfunction?

More than a thousand babies die in their sleep every year. Over the past couple of weeks, a study published in eBioMedicine has gained a lot of attention due to the identification of butyrylcholinesterase (BChE) as a potential biomarker for Sudden Infant Death Syndrome (SIDS). If confirmed by future studies, the presence of a biomarker would offer new hope for preventing this leading cause of death in infants less than one year old. 

In their study, the researchers evaluated BChE activity in dried blood spots taken routinely at two–three days after birth via a heel prick (Guthrie test) at the Children's Hospital Westmead in New South Wales, Australia. The dried blood spots were stored on filter paper for more than two years prior to analysis. Infants who had later died from SIDS were identified based on coroner reports at three forensic pathology sites in Australia. The BChE activity of 67 sudden unexpected infant deaths was each compared to 10 age- and gender-matched surviving controls (655 control infants total).

The study shows significantly lower activity of the cholinergic system enzyme butyrylcholinesterase (BChE) in infants susceptible to SIDS. The study authors hypothesize that this reflects cholinergic dysfunction, which in turn could alter autonomic and arousal responses, such as heart rate, blood pressure, and ventilation changes.

While altered BChE activity could provide insight into SIDS, the media clout touting it as a SIDS cure is doubtful, as described in a recent article in The Atlantic. Follow-up studies with diverse cohorts are needed to confirm the utility of BChE as a SIDS biomarker, and to understand the physiological relevance and mechanisms of altered BChE activity in SIDS.