Head growth in fetal life and infancy is
associated with later intelligence, new research
hints. Moreover, catch-up increases do not
appear to compensate for poor early growth.
"Brain growth in early life may be important
in determining not only the level of peak
cognitive function attained but also whether
such function is preserved in old age," the
study team writes in the journal Pediatrics.
"Older people with a larger head circumference
tend to perform better on tests of cognitive
function and may have reduced risks of cognitive
decline and of Alzheimer's
disease."
Several studies in children have shown that
those with larger brains, measured with imaging
studies or as head circumference, tend to
score higher on tests of cognitive function.
Similar associations have been found in adults.
For their study, Dr. Catharine R. Gale, of
the University of Southampton, UK, and colleagues
examined the effect of head growth in fetal
life, infancy, and childhood on brain power
at the ages of 4 and 8 years. Included in
the study were 633 term children who had their
head circumference measured at birth and at
regular intervals thereafter.
By age 1, mean head circumference increased
from 34.9 cm at birth to 46.6 cm. Head growth
after infancy was slower. Mean head circumference
increased to 50.9 cm by 4 years and to 53.4
cm by 8 years.
Average full-scale IQ was 106.3 at 4 years
and 105.6 at 8 years. The investigators report
that only prenatal growth and growth during
infancy were associated with later IQ.
At 4 years, after adjusting for parental
factors, there was an average increase in
full-scale IQ of 2.41 points for each 1 standard
deviation increase in head circumference at
birth and 1.97 points for each 1-SD increase
in head growth during infancy. This was conditional
on head size at birth.
Head circumference at birth was no longer
associated with IQ at 8 years. However, head
growth during infancy remained significantly
predictive, with full-scale IQ increasing
an average of 1.56 points for each 1-SD increase
in head growth.
SOURCE: Pediatrics October 2006.
