Colic in Infancy May Be More Than Just Gas

Babies cry. Some, however, cry a lot and seem less able to be soothed. Approximately 20 percent of young infants meet the criteria for colic, often defined by the “rule of three,” meaning a baby that cries for at least three hours a day for at least three days a week for at least three weeks.

While excessive crying in infants can be very distressing for parents, colic that does not come from a more serious medical cause is considered a "benign and self-limited process" that usually starts to get better by around six months of age. Its specific cause remains unknown, although most hypotheses and treatments focus on disturbances of a baby’s young gastrointestinal system.

When parents bring infants to their primary care clinician for concerns about colic, a common component of treatment is to provide a lot of reassurance that there is nothing serious going on and that this excessive crying does not forebode a long struggle with mental health challenges. This last point, however, is starting to be challenged by research.

Recently in the Journal of the American Academy of Child and Adolescent Psychiatry, an article was published using data from the rigorous Dutch Generation R (for Rotterdam) study that has followed nearly 5,000 children from before birth into adolescence. When infants were three months of age, the parents were asked whether their babies cried at least three hours per day (similar to the more official colic criteria), and 11 percent of mothers did endorse this. The children were then assessed multiple times across childhood and adolescence concerning levels of emotional-behavioral problems using standardized rating scales.

The study's main finding was that excessive crying in infancy significantly predicted higher levels of emotional-behavioral problems in childhood and, to a lesser degree, in adolescence. The finding held for both major types of behavioral challenges, including internalizing problems (like mood and anxiety) and externalizing problems (like aggression and rule-breaking).

Around age 10, the sample received an MRI scan. Those who cried excessively as infants were found to have a smaller amygdala, a part of the brain known to be important in processing emotions and stress regulation.

The magnitude of these associations was not large, and most infants with excessive crying grew up to be typically developing children with no elevations in mental health problems. Nevertheless, the authors of the study, based on their data and others, wrote that high levels of crying and irritability in early infancy shouldn’t be “shrugged off” and may reflect a vulnerability for later mental health challenges.

How this might work wasn’t directly tested in the study. It’s possible, for example, that for some infants, colic is a marker for a more irritable or dysregulated temperament that can endure over time. It’s also possible, however, that this early fussiness sets in motion more transactional processes in which infant irritability can lead to parental frustration and anger, further impacting the parent-child relationship. It’s also unclear if these documented brain changes underlie the link between excessive crying and later behavior problems or if these are separate processes.

While it’s important not to over-interpret these data, this study suggests that, for some infants, colic is more than “gas” and may reflect some neurodevelopmental vulnerabilities that can lead to further struggles. Some additional monitoring, parental support, and emotional regulation skill-building might help keep these initial differences from expanding to larger problems in the future.