A review paper written

1. Variation in Dopamine and Cortisol Levels in the Hypothalamic
Pituitary Adrenal axis and their Association with Pediatric
Aggression
Review
BIOL 3095
Gustavo A. Martínez-Muñiz
Abstract:
The Hypothalamic Pituitary Adrenal (HPA) axis is the part of the brain that controls the
reactions to stress of the body. The hormones these axes secrete are greatly involved in the
control of the behavior of the person. Any changes in the levels of hormones affect the behavior
of a person and the way in which they respond to stress in society. This paper focuses on the
responses of the human body and mind to behavior involving low levels of cortisol and
dopamine, which are produced by the HPA axis. In previous studies and papers it is shown that
low levels of cortisol are strongly associated with aggressive behavior, be it impulsive or
predatory.
Introduction:
Cortisol and dopamine are two
different hormones produced in the
Hypothalamic Pituitary Adrenal (or HPA)
axis in the human brain. The HPA axis is
what links the central nervous system with
the peripheral response system. These
hormones are greatly involved in the control
of behavior and impulses in the human
body, along with its emotions. These
hormones, found in varying levels
throughout the body, are involved in
different reactions to stress, which can result
in aggression in children. These results can
be associated with psychiatric disorders such
as Attention-Deficit or Hyperactivity
Disorder (ADHD) or Post-traumatic stress
disorder (PTSD). All of these disorders are
classified as pathologic types of aggression
in minors. Future expectations for this paper
would be to develop new foundations on
reasons for pediatric aggression in order to
give proper treatment to patients with
pathologic aggression.
Cortisol levels in the HPA axis:
Pathologic aggression is classified
as either physical or verbal aggression.
Physical aggression is divided into four
subtypes: impulsive, reactive, predatory, and
premeditated aggression. Impulsive and
reactive aggression are the types of

2. aggression that are reactions to stress or
stimuli. These types of aggression are
normally responses to intimidation or
attacks. Meanwhile, the predatory and
premeditated are the types of aggression that
are actually planned before-hand, and are
usually directed towards peers.
These four types of physical
aggression are common in psychiatric
disorders. Physical aggression combined
with verbal aggression, are commonly found
in children or teenagers who abuse their
peers. They are what is referred to bullies.
Verbal aggression can occur in two
ways. The aggressor uses verbal abuse to
intimidate or exclude his peers. Examples
like this are spreading rumors about a peer.
The second way is using verbal aggression
to affect one’s self with his or her own
words.
Studies have been done to study the
effects of abnormal or deficient levels of
these hormones in children and teenagers.
Further studies have been done to measure
the various levels of either cortisol or
dopamine that are either absent or excessive
in teenagers and children to determine the
treatment of such behavior for healthy
functioning in a social environment. In one
specific study, Van den Bergh B. et al
(2008), indicate that different measures of
cortisol were taken at different times of day
in order to measure if varying daily levels of
cortisol affect aggression.
This study involved the observation
of a group of 58 adolescents with self-
reported characteristics of aggressive
behavior, trait anxiety, and depressed mood
symptoms. Cortisol was measured from the
saliva samples of the teenagers at three
different points of the day. Flattened diurnal
cortisol levels, according to the results of
this study, showed that there was no
heightened aggression in the teenagers,
though it was associated with the other two
symptoms. In other words, low levels of
cortisol can be more strongly associated
with depressive mood and trait anxiety
symptoms than aggressive behavior.
Lopez-Duran N. et al (2009),
studied a group of 73 children who were
considered to be proactively or reactively
aggressive, and they associated that
aggressiveness to the HPA axis. It is the
main regulator of stress in the human body.
According to the article, proactive
aggression is the same as predatory or
premeditated aggression, whereas reactive
aggression is similar to impulsive
aggression. In the study, the children were
put through a series of fear-inducing or
frustrating stress tasks, and afterwards a
sample of their saliva was taken to measure
the levels of cortisol that they had in their
systems after being scared or frustrated.
Several samples of saliva were taken before
and after being put through the task, as well.
The results of this study showed that the
children who were exposed to stress or
fear-inducing tests had lower levels of
cortisol during the time closer to the
exposure to stress or fear. This would
indicate that aggressiveness would be higher
when the children were exposed to stress,
and that the child with reactive aggression
would have a stronger relation to the HPA
axis than a child shown to be proactively
aggressive.

3. Moreover, both of these studies show
that low cortisol profiles can be associated
with different types of aggressive behavior,
indicating that in order to treat the disorders
that a child or a teenager were diagnosed
with, cortisol is a hormone of interest to
measure in order to make a proper diagnosis
and treatment.
Internalizing vs. Externalizing
Behaviors and Cortisol
A study by Ruttle and associates
(2011) observes the association of
fluctuating levels of cortisol with either
internalizing or externalizing behavior.
Internalizing behavior are those that direct
the results of stressful situations to self. An
example of this form of behavior is clinical
depression. Externalizing behaviors are
those that respond towards others rather than
self in an aggressive manner.
The study was throughout the growth
of 96 youths and measuring cortisol from 20
daily samples of saliva. These samples were
taken throughout the late years of youth and
the early adolescence.
The results of the study showed that
children and adolescents with internalizing
behaviors were shown to have more
flattened diurnal cortisol profiles. Whereas
the morning cortisol level had no strong
association with the youths exhibiting
externalizing behaviors; indicating that
behavior problems in children and
adolescents can be linked to the
abnormalities in the quantities of cortisol
that are produced during the morning for the
patients that express these kinds of
behaviors. This would imply that the HPA
axis in the children or adolescents that have
these kind of behaviors or personality
changes have a blunted HPA axis. This
means that the HPA axis would not produce
the necessary amount of cortisol in the
morning.
A blunted HPA axis would then be
an important factor to study when observing
aggressive or depressive behavior in
adolescents. Further studies involving a
blunted HPA axis would be to observe what
factor would be the one that inhibits the
production of hormones, and whether or not
it is possible to stimulate the production of
the hormones.
Psychological observations on
aggressive behavior
Observing how aggressive behavior
is prevalent in social activities and
environments, it is an important point that
must be taken into consideration. In a
study , Hemphill et al. (2010), conducted a
survey in the states of Washington, USA,
and Victoria, Australia. The survey
consisted of interviewing students in the
fifth, seventh, and ninth grades. The purpose
of the survey was to observe how many
students were capable of attacking a peer
either physically or verbally, in order to
make that peer be unaccepted in the school
or look bad in front of the rest of the
schoolmates. The results of the survey
showed that boys were more capable of any
type of predatory or verbal aggression than
females, and that different stages of puberty
were also associated with the level of
aggression in the student. Other factors that
were taken into account were the
sociability of the student, drug and alcohol

4. abuse, and the state of their homes
(economic state of their parents, whether
they lived with both parents, one, or neither,
etc), and the types of friends the students
had in and out of school.
Some factors that could not be
observed in this survey were the hormonal
levels in the students, in order to not be
invasive.
Association of Dopamine in the
HPA axis
Barzman et al. (2010), states that low
cortisol levels in the HPA axis can be
associated to aggressive behavior, and that
pre-pubertal children with disruptive
behaviors would have low cortisol levels
when exposed to stress-inducing trials or
situations. Low cortisol is also associated
with aggression patterns and early
aggression developed in male children. The
authors state as well that abnormal levels of
a major dopamine metabolite, homovanillic
acid are associated with high levels of
aggression in grown males, especially those
convicted of murder. The same levels of the
metabolite are found to be associated with
aggressiveness and comorbid ADHD in
children.
Conclusion:
This review paper emphasizes the
importance of observing the levels of
cortisol and dopamine in children in order to
diagnose and treat the pathological
aggression that has been observed in
patients. Contextualizing these behaviors
with every day scenarios is also important in
order to identify what factors in the patients’
lives are the ones that are triggering the
stress causing the aggression. All this will
lead to improving the treatment of pediatric
aggression in psychiatric disorders and in
minors who attack their peers either verbally
or physically.
An important possibility of working
in the future would be to combine the
psychological survey with the measurements
of hormones of the HPA axis. It may
possibly aid in determining directly what
environmental factors are the ones that cause
minors to be aggressive, either towards
peers or themselves. Though in the studies
by Lopez-Duran et al. and Van den Bergh
et al. there were surveys, they were not as in
deep as the survey performed by Hemphill
et al. Such a survey goes deeper into the
reasons why the minors behaves
aggressively and can help associate that
behavior with the either low or high levels
of hormones.
As observed in the study conducted
by Ruttle et al. (2011), a blunted HPA axis
indicates a low production of hormones. If
studies cannot take place to study the
stimulation of hormone production, then the
patients would be studied to observe what
would be the amount of cortisol they would
need to function normally in society, and
afterwards, the hormones would be supplied
to them in the form of a medication or
treatment that will allow them to have the
hormones they need.
It is important for people to
remember that science is now opening doors
of knowledge. This would indicate that what
was once improper behavior now can be
identified as a biological disorder or disease

5. that can and must be treated in order for the
person to function properly in society.
However, treatment is only part of the
solution. Understanding on behalf of those
people the patient socializes with and lives
with is an important factor in completely
understanding and helping the behavior and
condition of an aggressive child or person. It
befalls not only on the patient, but those
around him or her as well, to help lead a
healthy and normal life.
References:
Barzman DH, Patel A, Sonnier L,
Strawn JR. 2010. Neuroendocrine aspects of
pediatric aggression: Can hormone measures
be clinically useful?. Neuropsychiatric
Disease and Treatment 2010:6 691 – 697
Hemphill SA, Kotevski A,
Herrenkohl, Toumbourou JW, Carlin JB,
Catalano RF, Patton GC. 2010. Pubertal
stage and the prevalence of violence and
social relational aggression. Pediatrics.
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doi:10.1542/peds.2009-0574.
Lopez-Duran NL, Olson SL, Hajal NJ, Felt
BT, Vázquez DM. 2009. Hypothalamic
Pituitary Adrenal Axis Functioning in
Reactive and Proactive Aggression in
Children. J Abnorm Child Psychol (2009)
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Ruttle P, Shirtcliff E, Serbin L,
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