Healthy infants older than three months who cry incessantly for no apparent reason may be at risk for lower IQ and behavior problems in their childhood years, new study findings suggest.

Such persistent, uncontrollable crying “seems to be a very good indicator of potential risk,” Dr. Malla Rao of the National Institutes of Health in Bethesda, Maryland, told AMN Health.

As such, Rao said, parents should not simply “dismiss” their child’s crying as being due to gastrointestinal problems such as heartburn or colic, but should notify their child’s pediatrician.

At younger ages, excessive crying among otherwise healthy babies is usually described as infantile colic, a common condition that affects up to 40 percent of babies, according to various reports. Although the constant crying is extremely stressful for mothers and the baby’s other caretakers, colic rarely lasts beyond 12 weeks of age and is not known to impact the infant’s long-term brain development.

Whether the same is true when the crying lasts beyond the age usually associated with colic is unknown. One team of researchers found that such unexplained crying that lasted for 6 months was associated with later hyperactivity among 8- and 10-year old children followed from infancy. Rao and his team investigated whether such prolonged crying may be associated with abnormal cognitive development as well.

A total of 561 women were enrolled during their second trimester of pregnancy. Their children were followed until 5 years of age, with periodic assessments during infancy and afterwards.

At the six-week assessment, 63 women - none of whom were anxious first-time mothers - reported that their child had experienced colic, or daily uncontrolled and unexplained crying that lasted two weeks or longer. For 15 of these infants, the same behavior was reported at 13 weeks, beyond the time frame usually associated with colic.

This prolonged crying after the colic stage was associated with poorer results on tests that measured cognitive development both in infancy and at 5 years old, Rao and his colleagues report in Archives of Disease in Childhood.

At 6 months of age, for example, infants with prolonged crying scored nearly five points lower on an intelligence test than those in the comparison group, who did not show any signs of colic at any age, and lower than those whose colic did not persist beyond three months.

At 5 years old, the prolonged criers had lower performance and verbal IQ scores than the comparison group, and also performed worse on tests measuring eye-hand coordination, the report indicates. These children were also more likely to be hyperactive and to have discipline problems than their peers.

None of the infants with prolonged crying had any brain-related or other major health problems that may have put them at increased risk for developmental problems, the researchers note. Also, the home environment of these infants was not greatly different from the others.

“Thus these findings indicate that prolonged crying itself may be a marker of subsequent impaired cognitive development,” Rao and his team write.

Parents with children who have prolonged crying should “be aware” that there is a potential for later cognitive problems, Rao said, but they should not be “overly worried” that their child will have a lower IQ. He advised that parents should inform their child’s doctor so they can together monitor the child’s speech, hearing and other developmental milestones.

It is “safer to follow” the child’s development “rather than ignore” the warning signs, Rao said. “There’s no turning back the clock later on in life.”

SOURCE: Archives of Disease in Childhood, November 2004.