WHAT DID THE AUTHORS STUDY?

In their article “Before the headache: infant colic as an early life expression of migraine,” Dr. Gelfand and colleagues¹ studied a large number of mother-infant pairs to better understand the cause of infant colic. Colic is defined as a situation in which an otherwise healthy baby cries or displays symptoms of distress frequently and for extended periods. In these instances, there is no clear cause for the discomfort. Colic usually starts within the first month of life, and often disappears rather suddenly. In most babies, colic stops before the infant is 3 to 4 months old. In some babies, colic can last up to 12 months.

The cause of colic is not well known. Limited data link infant colic to migraines. It is known that migraine is genetic: children of a person with migraines are more likely to have migraine as well. If colic is a symptom of migraine, one would expect that colic should occur more often if a parent had migraine. Dr. Gelfand and colleagues designed a study to better understand the relationship between colic and migraine.

HOW WAS THE STUDY DONE?

At the University of San Francisco Pediatrics Clinic, between July 2010 and September 2011, 165 mothers and their infants were studied. Dr. Gelfand et al. included infants between 2 and 12 weeks old in the study because colic symptoms peak in this age group. In the pediatrician's office, the mother completed a questionnaire to screen for colic in her baby, and migraine in herself. When present, fathers also filled out a questionnaire. The answers to the questions were carefully analyzed to determine if infants of migraineurs were more likely to have colic than infants of migraine-free mothers.

The authors used very specific criteria to define both colic and migraine. They used modified Wessel criteria to define colic. The baby needed to be crying for at least 3 hours a day for at least 3 days each week. For migraine, the mothers were asked if they were ever diagnosed with migraine. Since migraine is underdiagnosed, the researchers also used the ID Migraine questionnaire to screen for migraine. In other words, even if the mother was never diagnosed with migraine, Dr. Gelfand wanted to be sure that the mothers did not have migraine symptoms. The migraine survey required that the mother have at least 2 of the following during a headache: limitation of activity, nausea, and sensitivity to light.

WHAT WERE THE FINDINGS?

Dr. Gelfand collected 165 surveys. Eleven surveys were excluded for various reasons, leaving 154 for analysis. The average infant age was 8.0 weeks. A total of 55% of infants with colic were female while 47% of infants without colic were female. A total of 22 (14%) infants had colic by modified Wessel criteria. A total of 28 (18%) mothers had migraine either by a doctor's diagnosis or by the answers they gave on the ID Migraine survey. Fathers answered questions for 93 (60%) of the infants.

The key result was this: 29% of infants of mothers with migraine had colic compared to 11% of infants whose mothers did not have migraine. In other words, infants whose mothers had migraine were 2.6 times more likely to have colic. A paternal history of migraine was also associated with a possible increased prevalence of infant colic. However, there were not as many fathers involved in the study. This made analyzing the answers more difficult.

WHAT DO THE FINDINGS MEAN?

There are many important findings in this study. First, 14% of the infants in this study had colic. This is exactly that same as found by other researchers. About 5%–19% of infants have colic. This is important because it shows that the babies in the study by Gelfand et al. were no different from those in other studies in the United States.

Second, 18% of the studied mothers had migraine, which is the same as what has been reported in North America: about 18% of women have migraine. Just as with the infants, this tells us that the mothers are good representatives for other mothers across the United States.

In the past, one prospective study found that “hyperactive” infants were more likely to develop migraine. However, those authors did not look specifically at infant colic. Dr. Gelfand and colleagues found a significantly higher prevalence of colic in infants of migraineur mothers. Based on their data, they speculate that infant colic may be a precursor of migraine.

As with all studies, there were limitations to this study. The authors used the maternal history of migraine as a marker of the infant's genetic tendency to develop migraine. Although a maternal history of migraine does correlate with the likelihood of the infant developing migraines, the correlation is not exact. A study that follows infants with colic through childhood to see if they themselves develop migraines would be more accurate. Regardless, this study makes a substantial contribution to the understanding of colic.

This research has important implications both for researchers and caregivers. If a baby has colic, the doctor may try migraine medications as a treatment for the colic. Colic frustrates caregivers and puts colicky infants at greater risk for shaken baby syndrome. Successful treatment may protect infants against this syndrome. Although more research is needed, this study at least points out one possible reason for infant colic: migraine.