Study Shows that SIDS Babies Have Low Serotonin Levels

A new study published Wednesday in the Journal of the American Medical Association showed that babies who died from sudden infant death syndrome (SIDS) have lower levels of the brain chemical serotonin. The study, which was funded by the National Institutes of Health, showed that serotonin levels, which regulate a baby's sleep, heart rate and breathing, were 26 percent lower in the brainstems of babies who died from SIDS than in those of babies who died from other causes.

Researchers now believe that low serotonin levels may be the "fundamental abnormality" in babies who die from SIDS. Serotonin acts as a sort of alarm system in the brainstem, waking a sleeping baby when breathing is disrupted. Without it, babies can be unware that they are not breathing in enough oxygen, which thus causes them to die in their sleep, claims the study.

In addition, the study also found that babies with low serotonin also had low levels of the enzyme tryptophan hydroxylase, which is required to make serotonin. These levels were found to be 22 percent lower in the SIDS babies.

The study's author, Dr. Hannah Kinney of the Children's Hospital in Boston, said that the second phase of the study will focus on why some babies lack enough tryptophan hydroxylase to produce serotonin. Kinney said that she believes that researchers are still decades away from finding a physical marker of a brainstem problem that could be identified in the blood. To date, there is no test to determine whether an infant is at risk for SIDS.

While doctors are still trying to determine the cause of SIDS, it is recommended that parents make sure babies sleep on their backs, don't overbundle them, and don't leave loose bedding or stuffed toys in the crib.