Abnormal Psychology PSY404
CAUSES OF ABNORMAL BEHAVIOR
Many questions related to the etiology or causes of abnormal behavior come to one's mind. Such as
What causes depression?
Is it due to biochemical imbalance in the brain?
Is it caused by faulty thinking?
Are there any particular characteristics or lifestyles common among the depressed people?
The cause of abnormal behavior remains a mystery. So let us explore the mystery of the causal factors
underlying abnormal behavior. The major models of studying abnormal behavior or psychopathology
A model is a general orientation to the field of abnormal psychology. Every model has its own assumptions
about human behavior and its own set of hypothesis, how a mental disorder develops and each model
prescribes its own set of treatment.
The major models have their own individual interpretation of the etiological factors of abnormality.
No single model can explain behavior in a satisfactory manner. Therefore, psychologists today focus on
eclecticism, or they use the integrated approach in talking about etiology of a mental disorder.
Multidimensional Integrative Approach
Let us take an example of a sixteen year old girl who suffered from blood-injury-injection phobia.
We would like to study the issue of causation.
In this case, there are biological dimensions, there are psychological dimensions, Emotional, social and
interpersonal influences as well.
---So let us see this example: A young sixteen year old girl was referred for anxiety disorder, after repeated
episodes of fainting. In her biology class the teacher showed a film of dissection of frog, about half way in
the film she felt lightheaded and left the class. Then she began to avoid looking at injured people, visiting
sick at hospital, she could not stand the sight of raw meat or band aids used in covering wounds.--
The biological dimensions include causal factors from the field of genetics and neuroscience that is the girl
has a genetic predisposition to be phobic. So there is a biological dysfunction to be afraid of blood injury
injection. Psychological dimensions include causal factors from behavioral and cognitive processes,
including learning from environment, social learning and even un-conscious processes. The behavioral
responses will include tendency to escape and avoid situations where there would be blood or injury or
injection (hospitals or any road side accident). Emotional influences include increased fear and anxiety,
where as interpersonal influences which includes friends and family would always rush to help the victim
whenever she faints at the sight of blood. Finally, developmental influences would include that a young
sixteen old girl is passing through a difficult stage of development, she is in her teenage years where any
unfortunate phobic reaction may make her more ill at a later stage. n this example we have gone through the
biological influences, the behavioral influences, the emotional influences, social influence and
developmental influences. So we have adopted a multidimensional integrative approach to study blood
injury infection phobia.
Abnormal Psychology PSY404
Biological factors include genes and neuroscience. Increased
heartbeat, pulse rate, breathing, etc.
Avoidance to see blood or injury or injection, fainting spell.
Emotional / Cognitive
Increased fear and anxiety
Disruptions at school and home, friends and family run to help her,
doctors say nothing is physically wrong.
An important developmental stage of sixteen year old teenage girl.
The Bio-Psycho-Social Model studies how biological (evolution, individual genes, brain structure and
chemistry), Psychological (stress, trauma, learned helplessness, mood related perceptions and memories) and
social (roles, expectations, definition of normality and disorder) factors interact to produce specific
psychological disorders. The Multi-Dimensional Integrative Approach and Bio-Psycho-Social Approach are
Let us take another example:
On 8th October 2005, the northern areas of Pakistan experienced the worst earthquake in the history of the
country. Killing billions making a huge population homeless and without any social support. This traumatic
experience created earthquake phobia in every citizen of the country. You can apply this chart to any one
earthquake victim from your country.
1-Genetic contributions to psychopathology
What causes you to look like one or both of your parents or grand parents? The answer is Genetics or
· Genes are microscopic units of DNA that carry information about heredity. Genes are located on
chromosomes, threadlike microscopic structures found in the nucleus of cells.
· Behavior genetics is a much broader approach that studies genetic influences on the development
of normal and abnormal behavior. A genotype is an individual's actual genetic structure. It is
impossible to observe much of an individual's genotype directly. Instead, what we observe is the
phenotype, the expression of a given genotype. It usually is impossible to infer a precise genotype
from a given phenotype, because phenotypes, but not genotypes, are influenced by the
· Dominant/recessive inheritance causes some rare forms of mental retardation, but most mental
disorders are not caused by a single gene--Instead, they are polygenic, that is, they are caused by
more than one gene.
· Behavior genetic research is powerful, but unfortunately; people often misinterpret it. One serious
misinterpretation is that a psychological disorder is inevitable, even predestined, if it has a genetic
component. Nature and nurture are not separate influences on behavior. Nature and nurture always
Huntington a disease of the brain, it is due to genes that cause deterioration in a specific area of the brain
and causes changes in personality, such as cognitive functioning and motor behavior such as un controllable
shaking and jerkiness through out the body.
Another disease due to genetic influence is called Phenyketonuria caused at birth, it is caused by the
inability of the body to break down phenyl-alanine, a chemical compound found in many foods.
In a normal human cell 46 chromosomes are arranged in 23 pairs. In each pair, one chromosome comes
from father and one from mother. The first 22 pairs of chromosomes are programmed for the development
of body and brain and the last pair determines the individual sex. Most of our behavior, personality and
intelligence (IQ) is determined by many genes, each contributing only a tiny portion.
Abnormal Psychology PSY404
Behavior geneticists have developed important methods for studying broad, genetic contributions
to behavior, including family studies, twin studies, and adoption studies.
Family studies ask whether diseases "run in families." where as the Twin studies say that siblings,
DZ twins share an average of 50 percent of their genes, whereas MZ twins share 100 percent of
The key comparison involves determining the concordance rate of the two sets of twins;
specifically whether MZ twins are more alike than DZ twins are alike.
A twin pair is concordant when both twins either have the same disorder or are free from the
disorder, for example, both suffer from schizophrenia.
The twin pair is discordant when one twin has the disorder but the other does not, for example,
one twin has schizophrenia but the co-twin does not.
Remember that (1) most emotional problems, like most normal behaviors, appear to be polygenic;
(2) behavior genetic findings fail to specify the mechanism of genetic influence.
2-Gene and Environment interaction
Eric Kendel explored gene and environment interaction and their relationship to psychological disorder. We
will discuss two models 1-the Diathesis-Stress Model and 2-the Reciprocal Gene Environment Model.
In the diathesis-stress model individuals inherit characteristics traits from multiple genes and they have
tendencies to express certain traits and behaviors which may then be activated under conditions of stress i.e.
each inherited tendency is a diathesis which means a condition that makes one vulnerable to developing a
disorder. So when, a stressor comes along the disorder develops. In our example of a sixteen year old girl
suffering form blood injury injection phobia, we can say according to this model that she had vulnerability
or inherited tendency so when she saw the dissection of the frog that acted as a stressor and led to the
expression of disorder. So in this model of gene environment interaction, genetic predisposition was there
and environmental stress provided the opportunity for the disorder to be expressed.
The Reciprocal Gene Environment Model
There is now substantial evidence that people with genetic vulnerability to develop a certain disorder also
have a personality trait for developing a certain disorder such as in case of blood injury injection phobia, the
genetic predisposition, vulnerability and personality traits. All combined in the reciprocal gene environment
model. This model applies to the development of the depression in people.
3-Neuroscience and its contribution to psychopathology
· The field of anatomy is concerned with the study of biological structures, and the field of
physiology investigates biological functions.
· Neuroanatomy and neurophysiology are subspecialties within these broader fields that focus
specifically on brain structures and brain functions.
· The study of neuroanatomy and neurophysiology is the domain of an exciting, multidisciplinary
field of research called neuroscience.
Billions of tiny nerve cells--neurons--form the basic building blocks of the brain.
· Each neuron has four major anatomic components: the soma, or cell body, the dendrites, the axon,
and the axon terminal. The soma--the cell body and largest part of the neuron--is where most of
the neuron's metabolism and maintenance are controlled and performed.
· The dendrites branch out from the soma; they serve the primary function of receiving messages from
· The axon is the trunk of the neuron.
· Messages are transmitted down the axon toward other cells with which a given neuron
Abnormal Psychology PSY404
The axon terminal is the end of the axon, where messages are sent out to other neurons.
· Within each neuron, information is transmitted as a change in electrical potential that moves from
the dendrites and cell body, along the axon, toward the axon terminal.
· The axon terminal is separated from other cells by a synapse, a small gap filled with fluid.
· Unlike the electrical communication within a neuron, information is transmitted chemically across a
synapse to other neurons. The axon terminal contains vesicles containing chemical substances called
neurotransmitters, which are released into the synapse and are received at the receptors on the
dendrites or soma of another neuron. The process of reuptake, or reabsorption, captures some
neurotransmitters in the synapse and returns the chemical substances to the axon terminal.
· Neuromodulators are chemicals that may be released from neurons or from endocrine glands.
Neuromodulators can influence communication among many neurons by affecting the functioning of
The central nervous system consists of the brain and the spinal cord. The brain uses an average of 140
billion nerve cells called neurons to transmit information throughout the nervous system. A typical neuron
contains a central cell body with two kinds of branches; one kind of branch is called Dendrite having
receptor cells. The other kind of branch called axon that transmits nerve messages to other neuron. So the
brain and neurons are just like a powerful computer and the computer is programmed to control thinking
and actions of each and every organ of the body.
Nerve cells or neurons are not actually connected. There is a small space through which a nerve
impulse or message or nerve current must pass to get to the next neuron. This space between the
axon of one neuron and the Dendrite of another neuron is called the synaptic cleft. The chemical
that is released from the axon of one nerve cell and transmit the impulse to the receptor of another
cell is called the neurotransmitter (Specialized Chemical that defuses across the synaptic gap and
stimulates the next neuron).
Neurotransmitters and Psychopathology Scientists have found that disruptions in the functioning of
various neurotransmitters are present among some people with mental disorders.
· An oversupply of certain neurotransmitters is found in some mental disorders, an undersupply in
other cases, and disturbances in reuptake in other psychological problems.
· Abnormalities in the dopamine system in the brain may be involved in schizophrenia.
· Other evidence links the availability of various neurotransmitters with depression, hyperactivity,
posttraumatic stress disorder, and many other psychological problems.
· The identification of biochemical differences definitely does not mean that these problems are
caused by "a chemical imbalance in the brain," even though many people mistakenly leap to this
The list of neurotransmitters includes Acetylcholine, Nor epinephrine (Noradrenaline) Serotonin,
Dopamine, Glutamate and Gamma Amino Butyric Acid (GABA). Neurotransmitters are chemicals that act
Abnormal Psychology PSY404
on behavior. Increasing or decreasing the flow of neurotransmitters is important. Research on
neurotransmitters tells us that the production of neurotransmitters in different parts of the brain effect
behavior and mood.
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