Scientists seek cause of colic in babies

Sunday, August 18, 2002

Kristen and Doug Nelson wore out hair dryers, stairs, and patience trying to calm their crying baby, who wailed for much of her first four months of life.

They even found themselves frantically vacuuming at 3 a.m. because their newborn seemed soothed by the sound.

"My rugs have never been so clean," Kristen Nelson said.

Rhythmic noise and motion helped, but didn't cure baby Dana. The stubborn culprit was colic, one of the most dreaded, vexing conditions of infancy.

"Dana screamed for 14 hours one day at eight weeks. I thought I was going to lose my mind," the Madison, Wis., mother says of her now calm 2 1/2-year-old.

Though not a disease and considered by many experts to be ultimately harmless, colic continues to fuel research and frustrate parents; some experts even think it's to blame for many cases of child abuse.

Estimates suggest 10 percent to 20 percent of U.S. babies have colic.

Kristen Nelson, 33, says she and her husband visited the doctor countless times, certain their baby was seriously ill. The diagnosis that it was "just colic" was not very reassuring.

"It's just so draining because you can't comfort your baby; you feel like a complete failure," she said.

The main symptom is intense, inconsolable crying, and theories abound for its causes. The name stems from a Greek word relating to the colon, and recent research blaming carbohydrate or protein intolerance supports the long-held notion that digestive problems sometimes may be involved.

Simply communication

But another, more provocative recent study gaining popularity among pediatricians says most cases may simply be the way some normal, healthy babies communicate.

Perhaps most surprising, this theory suggests babies with colic aren't even in pain -- despite all their purple-faced, clenched-fist crying.

It's borne out of a sort of "squeaky wheel gets the grease" evolutionary theory and M.W. deVries' 1970s research in Africa's Masai tribe showing that more "difficult" babies survived a famine better than placid infants.

The newer study by Barbara Prudhomme White at the University of New Hampshire and longtime colic researcher Dr. Ronald Barr, a McGill University pediatrician, involved 40 2-month-old infants, the age when crying often peaks in colicky and non-colicky babies.

The researchers found that babies in the throes of colic had similar heart rates and levels of the stress hormone cortisol as babies without colic.

"They're not showing internal responses that you usually see in humans in pain," said White, a psychologist and occupational therapist.

While intense crying would seem to burn up lots of calories, the colicky babies didn't eat much more than calm babies and weren't any thinner.

"They were just as robust and healthy as all the other little babies were," she said. "They just cry a lot ... with not a lot of cost metabolically."

While colic was described in ancient times, the modern definition dates from the 1950s, and includes crying spells occurring at least three hours daily, at least three times weekly, for at least three weeks in early infancy. Each hard-to-soothe episode can last several hours and typically occurs around the same time every day, often in the afternoon and evening.

Gradually disappear

The spells tend to peak at two months and gradually disappear by about three or four months.

Nearly all babies have similar crying patterns, but those with colic are more intense, longer-lasting and harder to soothe, Barr said.

Colicky babies are sometimes gassy, a feature that has helped fuel digestive theories, but many doctors now think that occurs because crying incessantly involves swallowing lots of air.

"The first time a baby doesn't stop crying, he really needs to be evaluated by a physician to make sure there is nothing else going on," said Dr. Bennett Kaye, a pediatrician at Children's Memorial Hospital in Chicago.

If no underlying cause can be found, colic is the diagnosis.

While there is no cure, purported remedies abound. Research has shown one of the most popular medicines, simethicone drops, are ineffective.

"The mainstay of colic treatment is comforting, walking, soothing, swaddling," Kaye said. But he acknowledged that even that often doesn't work.

Research in the May issue of the journal Pediatrics suggested that colic in some babies is caused by an inability to properly absorb sugars in some fruit juice. Juices containing the artificial sweetener sorbitol and high levels of fructose were the main offenders.

Dr. Fima Lifshitz, the lead author and chief of nutrition at Miami Children's Hospital, said sugar that is not properly digested forms gas, which could explain the abdominal distention seen in some colicky babies.

He said the findings underscore the importance of recommendations by the American Academy of Pediatrics that babies younger than 6 months not be given fruit juice, which can cause diarrhea and offers no benefits.

Dr. Anthony Kulczycki Jr. of Washington University in St. Louis published data two years ago suggesting that some colic is due to an inability to digest proteins in cows' milk.

But Barr says evidence suggests fewer than 10 percent of colicky infants have protein intolerance. And those who do, he says, shouldn't be diagnosed with colic because the strict definition says there is no underlying ailment.

That's what can make the condition so hard for parents to handle. Though there's no firm data, many experts believe colic is a leading cause of child abuse, especially shaken baby syndrome.

The syndrome occurs when a baby is vigorously shaken, typically by a parent or caregiver upset over incessant crying. Such shaking can harm infants' fragile brains, causing eye injuries, brain damage or death.

White, whose 15-year-old son was a colicky infant, used to call him the "baby from hell" and remembers feeling some of the impulses that may lead some to abuse.

Barr is working with the center in developing a new awareness campaign tying colic-like crying with the syndrome.

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