Researchers have the best evidence yet that the brain chemical serotonin plays a role in sudden infant death sydrome (SIDS). In a new study, researchers genetically engineered mice to have low levels of serotonin at birth, and found that more than half of the mice abruptly died before they were 3 months old. More intriguing, they had erratic episodes where their heart rate would drop and, five to 10 minutes later, so would their body temperature, [study author Cornelius] Gross reported. Sometimes they died in the midst of what Gross calls those crises, other times afterward
[AP]
. Serotonin is most commonly known as a mood regulator involved in depression, but it also helps control some of the body's most basic functions, including breathing, heart rate, and body temperature. The mouse study supports earlier data gathered from the autopsied brain tissue of SIDS babies, which showed alterations in brainstem nerve ...
