Chapter 2- abnormal
THE GENERAL NATURE OF THEORIES
From early 20 century, there have been 2 main streams of thought concerning mental
o 1. Focus on the biological
o 2. Focuses on environmental influence
eg nature vs. nurture
Biological approaches tend to downplay the influence of influence of experience.
The psychological approach emphasizes environmental factors in the development of disorders.
John Locke stated humans are born tabula rasa (a blank slate upon which experience writes all
that is meaningful in thought and beh.)
Biological and psychodynamic formulations view dysfunctional beh as the product of forces
beyond the individuals control, whereas humanistic and existential approaches lay the
responsibility for action and choices squarely on the shoulders of the individual
The perspective taken determines many things- it directs research, guides directs the decision
and defines treatment responses
The behavioral perspective leads researcher so seen environmental events to shape specific
dysfunctional responses and emphasizes the classification of beh rather than of ppl.
This involves either manipulating the environment or modifying the perceptions ppl have
regarding their experiences and themselves
The adoption of a perspective is influenced far less by the weight of evidence than by the
prevailing social belief system and by an individual’s disposition to see human beh as
determined by factors beyond or within the control of the individual.
The clinging onto a theory is not always a bad thing since it allows that theory to be fully
A theory should be abandoned only when there is a better one available
Levels of theories
When biological psychological perspectives are applied to specific problems, they may become
theories that detail the supposed causal chain leading to their emergence of the dysfunctional
beh in question.
In single factor explanations, - once factor is said to cause the disorder: ego genetic defect
It often reflects the lack of current comprehensive knowledge of disorders.
Interactionist explanations, which view beh as the product of the interaction of a variety of
It is important to point out that most single factors models reflect the primary focus of the
researcher, theorist, or clinician rather than the belief that there really is a single cause.
Eg a cognitive therapist would emphasize the modification of negative automatic thoughts and
core beliefs in the treatment of depression.
Theories may be classified according to their level of explanation.
o Some theories try to explain all abnormal beh
o Others try to account for all disorders within a particular category eg personality
o There are theories that endeavor to reveal the causes of a particular prob such as panic
disorder o There are theories that attempt to elucidate the influence of a single factor within a
more general theory.
Single factor theories, however, should not be considered valueless simply because they may
later be discarded for complex explanation
Scientific theories are judged to be valuable not because they describe the enduring truth about
an issue, but rather because they embody three essential features
o 1. They integrate most of what is currently known about the phenomena in the simplest
o 2. They make testable predictions about aspects of the phenomena that were not
previously thought of.
o 3. They make it possible to specify what evidence would deny the theory.
Testing theories: the null hypothesis
A theory is replaced not because the evidence is not significant but because another theory
better explains it.
Experiments are not set up to prove the worth of a theory but rather to reject (or fail to reject)
what is called null hypothesis.
Null hypothesis proposes that the prediction made from the theory is false.
THE SEARCH FOR CAUSES
The aim for theories about mental disorders are to:
1. Expand the etiology ( the causes) of the probe beh
2. Identify the factors that maintain the beh
3. Predict the Couse of the disorder
4. Design effective treatment
Some ppl feel uncomfortable attributing causes of beh to factors over which a person has little
or no control
It is important to note that factors involved in the etiology of a problem may not be relevant to
o Eg many young ppl initially behind to drink alcohol, smoke, or do drugs to impress
others. To appear mature.
o Once entrenched, however, habitual use of alcohol, cigarettes, o drugs is maintained by
the direct effects of the substance, the distress induced by withdrawal, and
environmental cues such as being at the party with friends who drink, smoke or use
Even in disorders where there is a clear biological cause, environmental manipulations may
alleviate or even avoid the development of the most serious symptoms.
Ef phenylketonuria (PKU) is an inborn metabolic defect that cases the body to be unable to
metabolize phenylalanine, a substance presence in many foods
Untreated PKU will markedly raise blood level of phenylalanine, in a decrease in various
neurotransmitters in the brain, thereby producing severe mental retardation.
An even more pertinent observations derives from a study by Baxter and his colleagues (1992)
of patients suffering from obsessive-compulsive disorder
Many different theories have been advanced regarding the etiology of mental disorders.
We limit ourselves here to a description of the most popular, grouped by the primary proposed
cause 1. Biological, 2. Psychodynamic, 3. Learning beh or cognitive- behavioral theories), 4. Dysfunctional thoughts or beliefs (cognitive theories), 5. Intrapersonal processes (humanistic or
existential theories), 6. Socio-cultural influences.
It is reasonable to assume that theses various influences interact to reduce mental disorder.
Even within each of these models, various cases are seen as primary by one or another theorist
o Eg within the biological category, some theories emphasize abnormal brain functioning,
whereas others place the site of the problem in the autonomic nervous system, in
genetic endowment, or in a dysfunctioning endocrine system.
In fact, all of these systems work in concert and it is well- nigh impossible to distinguish their
Dividing this whole system into its presumed components parts all too often has the effect of
convincing some theorists that one or another aspect is causally more important than all other
This type of thinking, which may attribute primary causation to biological problems (biological
determinism), or to socio-cultural or environmental influences (cultural or environmental
determinism), is a form of reductionism, in that the actions of the whole are said to be caused
by (that is, reduced to the influence of) one or other of the component parts.
Strict biological determinism all too often leads to the dismal conclusion that psychological or
environment interventions will do not good.
When it comes to criminal beh , such arguments appeal to many ppl who wish simply to punish
offenders while ignoring the possible social factors related to a higher incidence of crime
Similarly, well intentioned clinicians may assume that disorders that are difficult to treat are
Recent studies suggest that cognitive therapy and other psychosocial interventions are effective
supplements to antipsychotic medication and are now recommended aspects of routine care.
Frequently, cultural or environmental determinists feel obligated to deny the influence of
However, no amount f devoted training, expert guidance, or determination would ever make a
person who is 1.5 meters tall into a world-class high jumper.
To understand the various theoretical approaches to abnormal beh, we will have to consider
them separately, as that is the way they have always been described. This separation, however,
should not be taken to mean that we agree with any one model that assumes the prior causal
control of beh.
Responses like endler’s (see green section on page 26) have encouraged many theorists to look
for biological causes of abnormal behavior.
Biological theorists of human beh typically not only borrow their model from medicine, but also
co-opt the Lang of medicine, calling clients: patients “and their problems “symptoms” or
“syndromes” and describing the response to these problems as treatment. Thus, adopting a
biological model has implications for the way in which people with problems are dealt with.
The same is true for all theoretical perspectives, and it is necessary to consider the ramification
of these often unnoticed implications when deciding on a particular point of view about
To appreciate the meaning of the various biological explanation of disordered beh or thinking, it
is necessary to have some understanding or relevant aspects of bodily functioning.
Biological theories have primarily implicated dysfunctions in or damage to the brain ( the central
nervous system, or CNS), problems of control of one or another aspects of the peripheral nervous system ( that is the autonomic nervous system or the somatic nervous system), or
malfunctioning of the endocrine system.
The purposes of exposition, the nervous system is divided into the CNS and the peripheral
nervous system, although in normal functioning and activities of these two complex systems are
integrated, and their actions are further coordinated with activity in the endocrine system.
The role of the central nervous system
The brain is estimation to have some 100 billion neurons and thousands of billions of glia cells
(presumed to be support cells, although recent evidence suggests that they exert a more active
role in neuronal functioning).
These cells group together into anatomically distinct, which appear to have somewhat
distinctive functions, although active interconnections throughout the brain indicate that no one
area exclusively performs any one function.
Fig 2.1 described the anatomical areas of the brain.
The hindbrain primarily directs the functioning of the autonomic nervous system, which in turn
controls primarily internal activities such as digestion, cardiovascular functioning and breathing.
The midbrain is the centre of the reticular activating system, which controls arousal levels (often
called sleep-wake center) and thereby attention processes.
The forebrain controls thought, speech, perception, memory, learning and planning- indeed, all
of the processes that make us sentient, self – conscious being.
Some disorders have been shown to be directly linked to brain damage
Dementia deterioration in all cognitive processes, particularly memory and learning) that occurs
to the loss or ineffective functioning of brain cells.
Losses of brain cell functioning can be transitory, but in many cases they are irreversible and
may result from various sources such as direct head injuries, disease, or toxins.
Neurotransmitters are the chemical substances that carry the messages from one neuron to the
next in the complex pathway of nervous activity within the brain.
Nerve cells are not connected to one another, so activity in one neuron doesn’t stimulate
activity in other neurons.
There is a gap called synapse between the axons or one neuron and the dendrites of
The transmission of the electrical activity in the axon to the neighboring dendrites occurs as a
result of the release of chemicals called neurotransmitters.
Certain neurons seem to be more sensitive to one or another type of neurotransmitter and
these neurons seem to cluster together, forming particular brain circuits.
When neurotransmitters are released into the synapse, some will be taken up at the receptor
sites on the dendrites and so it activates it or inhibits it. (Depending on the action of the
transmitter) an impulse in the post synaptic neuron.
Within the synaptic cleft are substances that deactivate neurotransmitters, so some of the
released transmitters are quickly drawn back into the releasing axon by a process called
Thus, abnormal beh can result from disturbance in neurotransmitter systems in various ways: 1.
there may be too much or too little of the neurotransmitter produced or released into the
synapse; 2. there may be too few or too many receptors on the dendrites 3. There may be an
excess or a deficit in the amount of the transmitter- deactivating substance in the synapse; or 4.
The reuptake process may be too rapid or too slow. Any or all of these problems can cause either too much excitation or too much inhibition in the
particular brain circuits and this excessive or reduced activity may result in abnormal
Disturbance in neurotransmitter systems are currently thought more likely to have general
rather than specific effects, and it is the interaction of various neurotransmitters and their
subtypes that is related to beh.
There is evidence that schizophrenia is caused by excessive dopamine, but this may be a false
Must see focus 2.1 page 28
It is important to note that the processes connecting beh and the neurochemical bases of brain
activity do not represent a one way street
No doubt neurotransmitter activity affects beh, but beh also affects neurotransmitter activity
Brain plasticity- It can be influenced by a number of experiences that occur pre and postnatal
thru hormones, diet ageing and stress. Disease and maturation.
The role of the peripheral nervous system
The peripheral nervous system includes the somatic nervous system which controls the muscles
and the autonomic nervous system (ANS). The ANS has two parts: the sympathetic nervous
system and the parasympathetic nervous system
These two systems typically function cooperatively to produce homeostatic activity in a variety
of bodily functions such as heart rate, digestive and eliminatory processes , sexual arousal,
In times of stress they function antagonistically: during stress or when a person feels threatened
the sympathetic nervous system readies the body for action ( fight or flight) by, eg increasing
heart rate, pupil sixe ad breathing.
At the same time the parasympathetic nervous system shuts down digestive processes, since
energy given to this function would be wasted in a time of emergency.
In some ppl the ANS response to stress is either exaggerated strong or remarkably weak
See the picture on page 29
The ANS (more particular, the sympathetic nervous system) is involved in fear and anxiety
Thus the overreaction ANS may increase readiness to acquire phobias or other anxiety
disorders, eg it is assumed by some behavioral therapists that conditioning processes are the
basis for acquiring anxiety disorders.
The strength of an individual’s ANS response to a frightening experience may determine
whether he or she acquires a conditioned phobic reaction. It has been found that there is a
heritable component to the level of emotionality
Individual differences in the regulation of various ANS and somatic nervous system functions
may also play a part in disordered beh.
Eg when patients diagnosed with generalized anxiety disorder (GAD) tend to show decreased
parasympathetic regulation of changes in heart rate and respiration when compared to non-
It appears that autonomic and somatic inflexibility may be particularly important to GAD
This inflexibility is seen in the chronic worry exhibited by an individual with GAD
The role of the endocrine system The CNS interacts with the endocrine system in a feedback loop that maintains appropriate
levels of hormones circulating in the bloodstream.
Hormones are chemical messengers that are secreted by various glandes
These secretions maintain bodily functioning and play an important role in the development of
The relationship of the endocrine glands both to each other and to the CNS is complex.
The pituitary (which is often called the “master gland” because it plays such as controlling role in
activating the other endocrine glands) releases many different hormones, some of which s we
have seen, activate other glands while others have a more direct action.
Growth hormones promotes and regulates muscle, bone and other tissue growth; prolactin
stimulates mild production in women
Two disorders are known to be related to malfunctioning endocrine glands.
Cretinism, a disorder involving a dwarflike appearance and mental retardation is a result of a
defective thyroid gland
Hypoglycemia, which results from the pancreas failing to produce balanced levels of insulin or
glycogen, produces experiences that mimic anxiety and some patients who report to anxiety
disorder clinics are in fact suffering from hypoglycemia.
One system that has been studied with regards to depression and anxiety is the hypothalamic
pituitary- adrenal (HPA) axis. The end result of this intricate system of communication between
the hypothalamus, the pituitary gland and the adrenal cortex is the release of cortisol
Cortisol is a hormone that is released into the bloodstream by the adrenal cortex in response to
a variety or stressors.
This hormone facilitates an individual’s response to short term threat by producing a number of
changes in the body.
Genetics and beh
It is reasonable to assuming that most of all beh are the products of an interaction between
these sources of influence.
Behavioural genetics – offers us an insight into the biological bases of abnormal functioning.
more research is emp on genotype-environment interaction
o IT APPEARS AS THOUGH GENES MAY INFLUECES BEH THAT CONTIVUTE TO
ENVIRONEMTS STRESSORS, WHICH INCREASE THE PSYCHOPATHOLOGY.
This type of reciprocal relationship between genetics and env has been found in animals and
Caspi and colleagues examined the interactive effects of a genotype associated with depression
and stressful life events. ( SLE)
The relationship between SLE and depression was much stronger among adults who have short
variant of a particular gene related to negative emotionality (5HTTLPR).
There is no direct link between he genotype and depression. … thus adults with this genotype
only developed depression if they also experienced SLE’s
Beh research into the genetic bases of psychiatric disorders usually take tree forms:
o Family studies, twin studies and adoption studies.
When the problem that characterized the index case also occurs in the comparison person, the
two are said to be concordant.
Concordance is thought to reveal the influence of genetics
More recent techniques for studying genetic influences include genetic linkage studies and
research methods in molecular biology. In genetic linkage studies, researchers line families with high incidence of a particular psychotic
Within these extended families, researchers look