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The ADD/ADHD Brain
he ADD/ADHD brain functions differently than a "regular"
brain. It is physically smaller (about 3-4% smaller),
and works in a different way. One area of the brain is
particularly affected by ADD/ADHD: the front-subcortical
Researchers have found that children with ADD/ADHD often
have "executive function" impairments.
An "executive function" is like a factory
foreman for the brain. Like a foreman organizing his workers,
the brain's "executive functions" make sure
that all the parts of the brain are organized, working
hard, and cooperating with other parts of the brain to
get work done.
The brain's executive functions control many aspects
of school and job performance. They must:
- hold information and assign it to the correct parts
of the brain
- get different parts of the brain started when tasks
- control emotion and frustration, making sure that
they do not get in the way of the brain's tasks
- control "self-talk" (e.g., thinking to
yourself, "I better get started on this homework
if I want to be done in time.")
- direct complex problem-solving by sorting information
to different parts of the brain and integrating the
results into a new idea
If a child's executive functions are not working properly,
the brain is not organized, and the quality of work decreases.
Level of Activity
The ADD/ADHD brain is less active than a normal brain.
This might be surprising, since the ADHD child is usually
far more active than other children.
Researchers can observe how active the brain is by using
a high-tech device called a Positron Emission Tomography
Scan—a PET scan. Using a PET scan, which is somewhat
like an X-ray for the brain, scientists can measure the
amounts of glucose that different areas of the brain are
using. Glucose is the brain's main source of energy, so
when one part of the brain is working hard, it consumes
Scientists at the National Institute of Mental Health
used PET scans to monitor the brain activities of people
with and without ADD/ADHD. They found that people with
ADD/ADHD have brains that are less active than others'
brains. Specifically, the parts of the brain that control
impulses and attention were significantly less active
in people with ADD/ADHD.
People with ADD/ADHD notice this brain inactivity in
their daily lives. They notice that their attention drifts
off all the time when they're doing boring and routine
tasks, and often complain that they are trying to think
through a fog.
The brain is a complex machine and ADD/ADHD a subtle
disorder. We know that the ADD/ADHD brain is working too
slowly, but we don't know why. Scientists, however, have
identified several factors that influence ADD/ADHD in
Pre-Natal Exposure: A major influence on the brain is
pre-natal exposure to drugs, alcohol, or cigarettes. Babies
who are exposed to drugs, alcohol, or cigarettes while
in the womb frequently develop ADD/ADHD symptoms in early
childhood. For a more complete discussion of the effects
of pre-natal exposure to drugs, alcohol, and cigarettes,
please visit Hardy Brain's Online Resource Center.
Toxins: Another possible influence on ADD/ADHD may be
environmental toxins. Scientists have found that animals
exposed to high levels of toxins such as lead often develop
ADD/ADHD-like symptoms. They suggest that lead from gasoline-contaminated
dirt and some types of paint and water pipes may cause
a child to develop ADD/ADHD. However, only a few cases
of this kind of ADD/ADHD have been found.
Genetic Influences: Another major influence on ADD/ADHD
may lie in a child's genes. Researchers have found that
most children with ADD/ADHD have a close relative who
also has the disorder or other disorders. When one identical
twin has ADD/ADHD, the other twin almost always has it
too. Also, fathers who had ADD/ADHD as children have a
30% chance of having ADD/ADHD children. Researchers at
the National Institute of Mental Health are now attempting
to track down an "ADD/ADHD-gene," though whether such
a gene even exists, no one knows.
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