"It's like they've lost the ability to put a contextual limit on when they're going
to be afraid and when they're not."
Childhood Maltreatment Can Leave Scars In The Brain
November 04, 2013
Girls are particularly vulnerable to brain changes caused by stress or
trauma, researchers say.
Maltreatment during childhood can lead to long-term changes in brain
circuits that process fear, researchers say. This could help explain why
children who suffer abuse are much more likely than others to develop
problems like anxiety and depression later on.
Brain scans of teenagers revealed weaker connections between the
prefrontal cortex and the hippocampus in both boys and girls who had been
maltreated as children, a team from the University of Wisconsin in the
Proceedings of the National Academy of Sciences. Girls who had been
maltreated also had relatively weak connections between the prefrontal
cortex the amygdala.
Those weaker connections "actually mediated or led to the development of
anxiety and depressive symptoms by late adolescence," says , a psychiatrist
at the University of Wisconsin and one of the study's authors.
Maltreatment can be physical or emotional, and it ranges from mild to
severe. So the researchers asked a group of 64 fairly typical 18-year-olds to
answer a questionnaire designed to assess childhood trauma. The teens are
part of a larger of more than 500 families that has been tracking children's
social and emotional development since 1994.
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The participants were asked how strongly they agreed or disagreed with
statements like, "When I was growing up I didn't have enough to eat," or "my
parents were too drunk or high to take care of the family," or "somebody in
my family hit me so hard that it left me with bruises or marks."
There were also statements about emotional and sexual abuse. The
responses indicated that some had been maltreated in childhood while
All of the participants had their brains scanned using a special type of MRI to
measure the strength of connections among three areas of the brain
involved in processing fear.
One area is the prefrontal cortex, which orchestrates our thoughts and
actions, Herringa says. Another is the amygdala, which is "the brain's
emotion and fear center," he says, and triggers the "fight or flight" response
when we encounter something scary.
Herringa says messages from the amygdala to the prefrontal cortex are
often balanced by input from a third area, the hippocampus, which helps
decide whether something is truly dangerous. "So for example if you're at
home watching a scary movie at night, the hippocampus can tell the
prefrontal cortex that you're at home, this is just a movie, that's no reason to
go into a full fight or flight response or freak out," Herringa says.
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At least that's what usually happens when there's a strong connection
between the hippocampus and prefrontal cortex, and the fear circuitry is
But Herringa says brain scans showed that in adolescents who had been
maltreated as children, the connection with the hippocampus was relatively
weak. He says in girls who had been maltreated, the connection with the
amygdala was weak too.
That suggests the fear circuitry wasn't working the way it should, Herringa
says. The result seems to explain something he sees in many young patients
with anxiety and depression and a history of maltreatment. "These kids seem
to be afraid everywhere," he says. "It's like they've lost the ability to put a
contextual limit on when they're going to be afraid and when they're not."
The finding that girls have weaker connections to two areas of the brain, not
just one, could help explain why they seem to be more sensitive than boys to
maltreatment, Herringa says.
The results of the new study are important because they suggest better
ways to diagnose and treat mental problems related to maltreatment, says ,
a psychologist at the University of Pittsburgh.
"Maltreatment is a disorder where often people are not even aware of the
extent of their symptoms," Siegle says. So having an objective test would be
"a significant advance," he says.
The study also shows that brain researchers are making some progress in
their quest to make mental health care more like physical health care, where
objective tests confirm a diagnosis and measure the effectiveness of
treatment, Siegle says.
"In psychiatry, in psychology, we very rarely have those tests because we
just don't know the biological and brain mechanisms," he says. "This study is
starting to get at what mechanisms we should be looking at."
|San Diego Education Report