Biology 202
2002 Second Paper
On Serendip

My father, like many Asian immigrants, left India to pursue his educational goals in America in
order to provide a better life for his family. He arrived in the U.S. with fourteen dollars in his
coat pocket, a suitcase in his hands, and a will to succeed. For my father, in a place like America
where opportunities were plentiful and where hard work actually paid off there was no excuse
not to succeed. The practical translation of this belief meant that if his children worked hard in
school there was nothing they too could not achieve. As such, in my father's household, not
doing well in school was not an option.

Because of his cultural background my father found my brother's poor performance in school
incomprehensible. I too was puzzled by my brother's attitude towards school. He and I grew up
in the same house with the same parents and the same set of values. Yet, he seemed to not care
about school at all. For a long time, my family and I attributed my brother's C's in school and
obvious inability to concentrate to laziness and a lack of motivation.

My brother's diagnosis with Attention Deficit Hyperactivity Disorder (ADHD) was both a
welcomed explanation and a shock to my parents. On the one hand, my mother and father had
begun to question their parenting abilities, and this allowed them to shift the blame from
themselves. On the other hand, they had a very limited understanding of mental illness. In
particular, the concept of mental illness itself was not something they were terribly familiar with.
For my parents, problems of the mind were problems that existed within the scope of personal
will power.

In many ways, I partially subscribe to the world-view that my parents hold. As such, until
recently, I've been skeptical of my brother's diagnosis. In particular, at the time, it seemed to me
that distractibility was something that I too suffered from. I didn't enjoy forcing myself to
concentrate, but I did it because I knew that I had to. In addition, my brother seemed perfectly
capable of concentrating when he was playing soccer, watching the Discovery channel or playing
video games. In my mind, his problems appeared to be that he was spoiled and didn't like being
told what to do. In addition, I think that ADHD gave everyone in my family the excuse that they
needed. My parents could absolve themselves of any blame and my brother could walk way
continuing to be distracted. Beyond my family, I thought that ADHD as a distinctly Western
phenomenon. Most kids regardless of culture don't like sitting still in desk in school, but only in
America is such a commonplace occurrence given the legitimacy of medical label. In fact, it
seemed to me that labeling kids with ADHD was a clever way for society to avoid reforming its
educational system. Needless to say my recent studies of ADHD have shown me how ignorant I
was about the disorder.

ADHD, often referred to as ADD (Attention Deficit Disorder) affects between 3 to 5 percent of
school age children 1)National Institutes of Health,gives the most recent official opinion on ADD.
According to a recent consensus paper by the National Institutes of
Health, the core symptoms of ADHD are developmentally inappropriate levels of attention,
concentration, activity, distractibility, and impulsivity 1)National Institutes of Health,gives the most recent official opinion on ADD.
In addition, the "exact nature and severity of ADHD symptoms varies from person to person" 2)Attention Deficit Disorder Association,information geared to people who have ADD.
These symptoms have to be excessive, long term and pervasive and they must create a real handicap in at least 2 areas of the
person's life. It is these criteria that set ADHD apart from normal distractibility 3)Attention Deficit Disorder Association,information geared to people who have ADD.

ADHD is a complicated disorder the causes of which are not well understood. As a result, there
are several controversies surrounding ADHD. In particular, there are controversies about the
actual existence of the disorder, whether it can be reliably diagnosed, and how it should be
treated 1)National Institutes of Health,gives the most recent official opinion on ADD.
This is because at some level defining the boundaries of developmentally
"appropriate" behavior and "normal" distractibility is a matter of personal opinion. The
previously mentioned core symptoms are just one example of the subjective nature of the
disease. According to one doctor, "If the behaviors or symptoms are not severe enough then by
definition it's not ADHD" 4)Attention Deficit Disorder Association,interview with a physician, Dr. Peter Jaksa.
The problem with diagnosing ADHD is that there is very little
consensus as to what is "severe enough" to be considered ADHD. In particular, no independent
diagnostic tests to date exist and interview tests are the only means to diagnose the disease.

Fortunately, advances in neurological screening and genetics are beginning to shed light on the
biological aspects of ADHD. As a result of this progress, in the future, more objective
diagnostic criteria may be available. Imaging studies have implicated certain regions of the
nervous system. According to one study, the prefrontal cortex, the two basal ganglia (the
caudate nucleus and the globus pallidus), and the vermis region are significantly smaller in
children who have ADHD 5)Scientific America,great article about research surrounding ADD.
These findings are telling because each of these regions is closely
associated with the core symptoms of the disorder. In particular, the prefrontal cortex is the
considered the command center of the brain and is involved in regulating the ability to inhibit
responses 6)WebMD Lycos,general informationon ADD.
The basal ganglia, clusters of nerve cells located near the center or the brain,
manage the impulses coming to and from the prefrontal cortex. Taken together abnormalities in
these regions provide an insight into the impulsive nature of individuals who have ADHD 6)WebMD Lycos,general informationon ADD.
Although the exact role of the vermis region is not understood, previous studies suggest that it
may be involved in regulating motivation 5)Scientific America,great article about research surrounding ADD.
According to several studies, the shrinkage of these particular structures in individuals with ADHD may be due to mutations
in several genes that are normally active in these regions 5)Scientific America,great article about research surrounding ADD.

Not only are there anatomical differences in individuals who have ADHD, there are
pathophysiological differences in individuals who have ADHD. In particular, the
neurotransmitter dopamine has recently become the focus of much ADHD research. Dopamine
is "secreted by neurons in specific parts of the brain to inhibit or modulate the activity of other
neurons, particularly those involved in emotion and movement" 5)Scientific America,great article about research surrounding ADD.
The impetus for the interest in researching dopamine can be traced to the fact that the standard medications for ADHD, such
as methylphenidate, target dopamine transporters. According to one 1999 study, in comparison
to individuals without ADHD, the density of dopamine transporters was elevated by
approximately 70% in individuals with ADHD 7)Internet Association for Biomedical Sciences,research article.

Not surprisingly, genetics seems to be the missing link between the anatomical and the
pathophysiological aspects of the disorder. Several studies have shown that the genes that
encode for dopamine receptors and transporters are very active in the prefrontal cortex and basal
ganglia 5)Scientific America,great article about research surrounding ADD.
However, there is other proof beyond this that suggests that genetic factors are a
major factor in the disorder. In particular, studies have shown that ADHD has a heritability
approaching 80% 5)Scientific America,great article about research surrounding ADD.
Although most researchers agree that ADHD is a polygenic disorder, the
genes coding for the dopamine receptors (D4) and transporters (DAT 1) have been the focal
points of recent research. Dopamine binds to receptors on certain neurons and thereby transmits
its message to these neurons. Mutations in these receptors can result in them being less sensitive
to dopamine 5)Scientific America,great article about research surrounding ADD.
As such, this could lead to a marked increase in extracellular dopamine.
Dopamine transporters, on the other hand, exist on the surface of dopamine secreting cells. They
function by actively recycling unused dopamine so that it can be used again 8)Med InfoSource,information about dopamine.
Mutations that render transporters inefficient would also lead to an increase in extracellular dopamine. A 1992
study showed that the 3'-noncoding region of DAT contains a polymorphic variable nucleotide
tandem repeat (VNTR) 7)Internet Association for Biomedical Sciences,research article.
In particular, a 10-copy repeat of a 40-base unit was found to be
associated with ADHD 7)Internet Association for Biomedical Sciences,research article.
These studies seem to suggest that elevated dopamine transporter levels may be a trait of ADHD.
As such, if further studies confirm this hypothesis, physicians
may have a concrete method for diagnosing ADHD

ADHD is not unique in that it is difficult to diagnose. Like many other neurobiological disorders
it is complicated and multifaceted. The recently discovered genetic basis for ADHD reveals the
extent to which genetics influences the brain equals behavior. For me, personally, my
experiences with brother's ADHD have taught me to be wary of my own personal biases when it
comes to mental health.

References

1)National Institutes of Health,gives the most recent official opinion on ADD

2)Attention Deficit Disorder Association,information geared to people who have ADD

3)Attention Deficit Disorder Association,information geared to people who have ADD

4)Attention Deficit Disorder Association,interview with a physician, Dr. Peter Jaksa

5)Scientific America,great article about research surrounding ADD

6)WebMD Lycos,general informationon ADD

7)Internet Association for Biomedical Sciences,research article

8)Med InfoSource,information about dopamine

9)

10)11)


| Forums | Serendip Home |