Scientists Think

Natural Hormones

Linked To Sids

May 21, 1994|By WARREN KING Seattle Times

SEATTLE — Natural hormone production in infants could play a significant role in sudden infant death syndrome, a medical mystery that has long baffled scientists.

University of Washington researchers think surging hormones - testosterone in males, estradiol in females - could inhibit some babies' breathing during the second through fourth months, a peak time for sudden infant death syndrome, or SIDS.

Michael Emery, a University of Washington researcher in physiology and biophysics, stressed that the theory, based on experiments with monkeys, needs much more study.

But he said, "I think it's good theory because it can explain a lot of things that have been difficult to explain. ... It's probably the first reasonable explanation for the age distribution of children who die of SIDS."

If the theory proves true, physicians could measure hormone levels and predict which babies are most at risk for SIDS. Drugs could be used to reduce the levels, Emery said.

SIDS is the most common cause of death in infants ages 1 week to 1 year. About 6,000 to 10,000 babies a year are victims of this "crib death."

The infants die because they stop breathing, but no one knows why the respiration stops. Emery, a doctoral candidate and director of the research project, is the first to explore the notion that hormones play a role.

He and his advisers, Michael Hlastala and Alvin Matsumoto, both University of Washington medical school professors, report their findings in the Journal of Applied Physiology.

Emery tested the theory on three infant monkeys at the university's Regional Primate Research Center.

The monkeys were castrated so there would be no natural production of the male hormone testosterone, which is produced in the gonads. The monkeys were placed in special chambers where their breathing rates and volumes could be measured during sleep, the time when SIDS almost always occurs.

When the animals were given infant levels of testosterone, and then 5 percent more carbon dioxide than in room air, their ability to adapt their breathing was significantly impaired.

Emery theorizes the same thing would happen with the female hormone estradiol. Most important, he said, the hormone-respiration link makes sense because it fits patterns seen in SIDS and other observations.

About a month after birth, babies start producing their own testosterone or estradiol near adult levels. This probably is to stimulate development of the brain and reproductive systems. It drops off at four or five months. About 95 percent of SIDS occurs before age 6 months.

Sun Sentinel Articles