It's every parents' dread, and the trigger of many instances of abuse and even death at the hands of stressed care givers -- a baby who won't stop crying. Yet colic, despite intensive research, continues to baffle doctors today just as it did a century ago, when the Russian writer and physician Anton Chekhov wrote in his 1906 story, ''Sleepy-Eye," about a nanny who murders a colicky baby.
In the absence of any genuinely useful treatments, parents and pediatricians resort to a variety of unproven ones. In many ways, this hints at a larger issue in medicine: How do families and doctors cope with untreatable conditions? Interestingly, the lack of any one effective therapy leads us to create an entire folklore.
On average, normal newborns cry between one and three hours a day. This behavior is universal. Among the Kalahari !Kung, a hunter-gatherer tribe in Africa whose mothers continuously carry and nurse their offspring, infants cry just as often as modern American babies. Even animals like chimpanzees, sea gulls, and burying beetle larvae display fussing behavior in infancy.
Roughly one in 10 infants, however, is said to have clinical colic, somewhat arbitrarily defined as inconsolable crying for more than three hours daily at least three times a week. It can be devastating to parents. Last week, one mother wrote in a colic support website: ''Boy, do I feel like I made the wrong choice [to have a baby]. I just keep hoping and praying it will get better."
In many cases, desperate parents develop their own theories about the causes and treatment of colic. Only a few decades ago, colicky infants were treated with an over-the-counter patent medicine called paregoric, which basically is 100-proof alcohol laced with opium extract. This month, the journal Pediatrics reported that almost one in 10 urban Michigan parents treats infant colic with catnip. In the study, many parents also considered head massage, laxatives, and even cigarette smoke for colic. Convinced that colic is caused by feeding problems, parents switched formula brands an average of nine times in another study. And a prestigious medical journal recently featured a report about chiropractic spinal realignment for colic. (It didn't work.)
Most commonly, parents believe excessive bowel gassiness causes colic, since many colicky babies have swollen, gurgling bellies after eating. People, however, normally swallow a half-teaspoon of air with each mouthful while eating, and they easily eliminate gas by burping or flatulence. X-ray studies of colicky infants demonstrate they swallow air after they've already started crying. Still, many parents use simethicone (Mylicon) drops, which make intestinal gas more slippery and easy to pass. But two well-designed clinical trials failed to show this was better than taking a placebo, an inactive dummy pill, for colic.
An equally unlikely theory concerns lactose intolerance. The small intestines of affected adults can't absorb lactose, which then passes directly into the colon. There, bacteria feast on lactose, creating hydrogen gas as a waste product. The average person passes between 1 to 3 quarts of gas daily, usually expelled in 10 to 20 bursts, but lactose-intolerant people can produce much more. Since both breast milk and infant formulas contain lactose, numerous studies have looked for excess hydrogen in colicky babies' intestines and none has shown a convincing correlation. Further, giving lactose-free formula doesn't help.
Doctors frequently do no better than many parents, as Cincinnati gastroenterologist Philip Putnam writes in one journal, when they diagnose acid reflux as the cause of colic. Putnam worries that doctors succumb to the ''urge to irradiate, sedate, and medicate" when they blame acid reflux. In a remarkably well-done 2003 Australian study of supposed infant acid reflux, the powerful antacid drug, Prilosec, didn't decrease crying in colicky kids, despite successful acid neutralization.
Theory after theory regarding colic has been debunked, with the exception of a few studies showing minor benefits for very small numbers of babies treated with specific formula changes, decreased stimulation, and herbal tea. Other treatments that appear to work do so only because colic gets better on its own. When they are compared with a placebo like sugar water, they turn out to be no better.
Into the vacuum of useful therapy, Dr. Harvey Karp's best seller, ''The Happiest Baby on the Block," inserts yet another hypothesis: Colic means that a baby's brain needs extra time to develop. With absolute seriousness, Karp suggests that parents should create a ''fourth trimester" of pregnancy by wrapping infants tightly to re-create the womb environment, and make hissing noises in infants' ears to simulate the sounds of blood flow in the uterus. Though it's hard to dispute Karp's commercial success, his idea has yet to be studied in any scientific manner.
Medicine has a rich tradition of made-up explanations for vexing problems. People have an inherent need for explanations, regardless of how insensible they are. For example, an equal number of subjects in a classic 1978 study were permitted to cut in line at a copier if they explained ''I have a deadline" (a good reason) or just ''I need to make some copies" (a bad reason); far fewer were permitted if no reason was given. When coupled with the immediacy of a screaming baby, this human tendency leads parents and pediatricians to grasp at almost any explanation for colic, even if it's not supported by science.
Still, I need to come clean. As the father of a colicky baby myself, I found that having a name for our painful situation, some explanation, and something to do, no matter how nonsensical, helped me feel better. Despite the data, I tried the Mylicon and even a formula change, violating the age-old medical precept that, when in doubt, one should not just do something but stand there. Just maybe, I thought in my confused late-night mind, all those researchers were wrong. My better judgment did return, but only after my son's colic got better.
Dr. Darshak Sanghavi, a clinical fellow at Children's Hospital and Harvard Medical School, can be reached at www.darshaksanghavi.com.