Breathing Problems During Sleep May Affect
Mental Development in Infants and Young Children
Children who have problems breathing during sleep tend
to score lower on tests of mental development and
intelligence than do other children their age, according
to two studies funded by the National Institutes of
Health (NIH). Both studies appear in the October issue
of Journal of Pediatrics.
The first study, funded by the National Institute of
Child Health and Human Development (NICHD), found
that at one year of age, infants who have multiple,
brief breathing pauses (apnea) or slow heart rates
during sleep scored lower on mental development tests
than did other infants of the same age. The second
study was funded primarily by the National Heart,
Lung, and Blood Institute (NHLBI). Results show that
5-year-old children who had frequent snoring, loud
or noisy breathing during sleep, or sleep apneas observed
by parents scored lower on intelligence, memory, and
other standard cognitive tests than other children
their age. They were also more likely to have behavioral
problems.
“The findings from these studies support other
research that has shown that breathing problems during
sleep are associated with serious health consequences
in children,” said Carl E. Hunt, M.D., director
of the NIH National Center on Sleep Disorders Research
(NCSDR). “However, at this point we don’t
know if the sleep problems during these episodes cause
the decline in test scores or if the sleep episodes
and the lower test scores are both related to some
common underlying mechanism.”
More than 10 percent of young children have habitual
snoring, the mildest form of sleep-disordered breathing
(SDB). One to three percent of children have obstructive
sleep apnea, a more severe form of SDB in which breathing
stops briefly and repeatedly during sleep. SDB is
thought to be more common in toddlers and younger
children than in older children because the younger
ones are more likely to have large tonsils and adenoids,
which can briefly block the airways in the back of
the throat during sleep. African American children
are twice as likely to develop SDB compared to white
children. Children who are overweight or obese are
also more likely to develop SDB.
In the first study, researchers evaluated 256 full-term
and preterm infants at one year of age with a standardized
test that measured physical and mental development.
The infants were part of the multi-center Collaborative
Home Infant Monitoring Evaluation (CHIME) study. The
CHIME study sought to identify factors that could
put infants at risk for sudden infant death syndrome
(SIDS). Participants included healthy infants as well
as those at increased risk of SIDS because they had
a history of prematurity, a life-threatening event
during sleep, or a sibling who had died from SIDS.
The infants’ breathing, heart rates, and blood
oxygen levels were monitored electronically at home
for the first 4-6 months of age.
The researchers found that infants who totaled more
than five episodes of abnormally slowed heart rate
or apnea during the period they were monitored scored
lower on the mental development test at one year of
age than did infants who experienced fewer or no such
episodes. The episodes were often associated with
drops in oxygen levels.
The lower mental development scores persisted even
after data were adjusted to correct for other factors
known to affect mental development in preterm infants.
The study also found that full-term infants who experienced
the abnormal episodes scored lower on the tests than
did other full term infants, according to Hunt, the
lead author, who conducted the research while at the
Medical College of Ohio in Toledo.
The second study involved 205 children at 5 years of
age. Researchers at Boston University School of Medicine
compared neurocognitive function and behavior of 61
children with SDB symptoms to 144 children without
symptoms. Symptoms of SDB, as reported by parents,
included frequent snoring; heavy, loud, or noisy breathing
during sleep; or observed apneas during sleep. An
overnight sleep test (polysomnogram) was also performed
to objectively measure the severity of SDB.
The study found that children with SDB symptoms scored
lower on standard tests measuring executive function
(attention and planning), memory, and general intelligence.
These children also had significantly more behavioral
problems than children without SDB symptoms, based
on parental survey scores.
“One of the more remarkable findings in this
study was that the neurocognitive effects were significant
even among the children who had mild symptoms of sleep-disordered
breathing but no actual sleep apneas,” said
Daniel Gottlieb, M.D., M.P.H., lead author of the
study. “Parents need to be aware that their
child’s snoring could signal serious problems.”
The mild SDB symptoms associated primarily with snoring
in these children result in frequent arousals and
fragmented sleep, leading to poor sleep quality and
hence to sleep deprivation. Today’s findings
are similar to other studies of children and adults
that link poor sleep or sleep deprivation to problems
with school (or job) performance, difficulties with
memory and concentration, increased risk of injuries,
and trouble controlling impulses, emotions, and behavior,
especially in children.
“Unfortunately, the effects of poor sleep are
often overlooked or misinterpreted in children. Rather
than appearing sleepy like adults who are sleep deprived,
children may in fact seem to be more active or even
hyperactive,” comments Hunt.
In an accompanying editorial, Hunt notes that brain
development is not complete until at least late childhood,
and hence children may be uniquely vulnerable to SDB
symptoms and their consequences, especially if such
symptoms begin during infancy or early childhood.
Brain areas, such as the prefrontal cortex, which
regulate executive function, might be particularly
susceptible to damage from SDB, writes Hunt.
In addition, other researchers have reported that the
effects of SDB appear to have long-term consequences
for children. For example, a University of Louisville
study found that young children who snored loudly
and frequently were more likely to have lower grades
in middle school – even several years after
the breathing problem was treated or resolved.
“These two new studies point to the need for
parents and pediatricians to be on the watch for what
might appear to be less serious breathing problems
in their babies and young children when they sleep,”
notes Hunt. “If we can identify these children
before the effects on mental development have occurred,
the challenge then will be to identify possible ways
to intervene and prevent any reduced potential for
doing their best in school.”
Scientists have not yet determined safe and effective
ways to reduce cardiorespiratory episodes in infants.
In children, however, treatment for SDB typically
involves having the tonsils and adenoids surgically
removed. In more severe cases, or for children who
cannot have surgery, a machine known as continuous
positive airway pressure (CPAP), which forces air
into the air passages while the patient is sleeping,
can be as effective in children as it is in adults
with sleep apnea.
The health consequences associated with SDB in children
are gaining increasing recognition. In April 2002,
the American Academy of Pediatrics established clinical
practice guidelines on obstructive sleep apnea in
children. The guidelines call for all children to
be screened for snoring and for children diagnosed
with obstructive sleep apnea to be treated.
Resources
For more information about sleep and sleep research,
visit the National
Center on Sleep Disorders Research Web Site (http://www.nhlbi.nih.gov/sleep).
“Sleep
Well. Do Well. Star Sleeper Campaign,” featuring
Garfield the cat, (http://starsleep.nhlbi.nih.gov).
SIDS
and the "Back to Sleep" Campaign, (http://www.nichd.nih.gov/sids/sids.cfm)
AAP
Clinical Practice Guideline on the Diagnosis and Management
of Childhood Obstructive Sleep Apnea Syndrome
(http://www.aap.org/policy/re0118.html)
NICHD and NHLBI are part of the National Institutes
of Health (NIH), the biomedical research arm of the
federal government. NIH is an agency of the U.S. Department
of Health and Human Services. NICHD publications,
as well as information about the Institute, are available
at http://www.nichd.nih.gov,
or from the NICHD Information Resource Center, 1-800-370-2943;
e-mail NICHDInformationResourceCenter@mail.nih.gov.
NHLBI resources are available at http://www.nhlbi.nih.gov,
or from the NHLBI Health Information Center, (301)
592-8573; email NHLBIInfo@nhlbi.nih.gov.
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