Exposure Before Birth Could Affect Kids' Decision-making
The part of the brain responsible for making most
decisions about how to behave seems to develop less quickly
in children exposed to cocaine before they were born,
University of Florida researchers have found.
Using a new form of magnetic resonance imaging, researchers
compared 28 adolescents exposed to a mix of cocaine and
other drugs in the womb with 25 children whose mothers did
not use cocaine during pregnancy and pinpointed subtle
differences in how the brain's frontal lobe developed.
Researchers noticed that pathways in the frontal lobe, which
connect to other parts of the brain to send information,
were not as well-defined in children exposed to cocaine
before birth, according to findings published this month in
the journal Pediatrics.
The children exposed to cocaine also fared slightly worse on
tests designed to assess skills linked to the frontal lobe,
such as when to act and when to stop, said Tamara D. Warner,
Ph.D., a UF research assistant professor of pediatrics and
the study's lead author.
"We actually found that there is a relationship between the
behavior and the brain," Warner said. "There were
significant associations with how well children were able to
do certain tasks and how well-developed the connections in
the brain were."
Some of the children whose mothers did not use cocaine were
exposed to alcohol, tobacco and marijuana, but they did not
exhibit the same subtle differences in the brain. Because
the mothers of children exposed to cocaine used multiple
drugs, how these drugs interacted was likely a big part of
the problem, Warner said. The mothers had taken cocaine and
varying combinations of alcohol, marijuana and tobacco, and
the interactions among these drugs often are complicated,
sometimes producing additional toxic substances, Warner
To get a better glimpse of the frontal lobe, researchers
used a form of imaging that allowed them to see how water
flows through pathways linked to other parts of the brain.
How the water moved through these channels showed the
researchers how developed these pathways were in each
child's brain. The pathways were more mature in children
whose mothers did not use cocaine and not as well-formed in
the children whose mothers had, the study showed.
The children, who ranged in age from 10 to 12 and were from
similar socioeconomic backgrounds, also participated in two
behavioral tests that Warner likened to "Simon Says" types
of activities. On one test, children were asked to look at
the word "red" but then name the color of the ink used to
write the word. This showed how well they were able to
ignore the instinct to read the written word and give the
correct answer. On another test, which Warner likened to
"connect the dots," children were asked to connect a series
of numbers in order on a page and then perform a similar
exercise alternating between numbers and letters. The
children in the drug-exposed group named fewer colors
correctly and took longer to adapt to connecting both
numbers and letters, Warner said.
Including observations about how the brain looks and
behavioral test results in the study is important because it
links an actual brain change in children to a behavior
change, said Lynn T. Singer, a professor of pediatrics,
psychology and general medical sciences at Case Western
Reserve University who also studies prenatal cocaine
exposure in children.
"This is one of the first findings that shows there is a
difference in the way the brain works in (children exposed
to cocaine)," Singer said. "It's a very important study in
that we're getting new evidence of specific brain changes.
The way the brain is wired is different for these children."
Despite these subtle signs of damage, UF researchers say
children exposed to cocaine before birth are still faring
far better than people predicted in the 1980s, when they
were dubbed "crack babies." Past studies at UF and other
institutions have shown that children exposed to cocaine
before birth exhibit no more behavioral problems as toddlers
than other children, have average IQ scores and face only
slight problem-solving difficulties in school.
But the biggest questions won't be answered until the
children age, Warner said. Researchers do not know yet how
these differences in the brain's frontal lobe will affect
children as they enter their teen years and are faced with
peer pressure and tough decisions.
"Not knowing when to stop and when to inhibit your behavior
could have much wider consequences than a Simon Says game,"
Warner said. "The differences we found were intriguing, but
they really are the first piece of the puzzle in understand
how these children are developing."
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