Abnormal Psychology – PSY404 VU
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LESSON 14
CAUSES OF ABNORMAL BEHAVIOR
ETIOLOGICAL FACTORS OF ABNORMALITY
We have talked about the different models of Psychology; each model represents its own unique
interpretation of the etiology and treatment of abnormal behavior. After studying each model we extracted
(located) some important factors underlying abnormality. From the study of biomedical model we have
located the biological factors of abnormality similarly, after going through the Psychoanalytic model,
Humanistic Model, Behavioral model and Cognitive model we extracted the psychological factors,
emotional and social factors. All these factors, they combine together in Bio-Psycho-Social approach or
multidimensional integrative approach. The biological factors focus on genetics, the interaction of genes
and environment. This model also focuses on neuron, brain and spinal cord.
1-Biological Factors
a- Genes and its interaction with environment
• b-The study of neuro-anatomy and neurophysiology is the study neuroscience. The Neuron
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 dendrites branch out from the soma; they serve the primary function of receiving messages from
other cells. The axon is the trunk of the neuron. Messages are transmitted down the axon toward
other cells with which a given neuron communicates.
• 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.
c- Major Brain Structures
• Neuro-anatomists divide the brain into three subdivisions: the hindbrain, the midbrain, and the
forebrain.
• Basic bodily functions are regulated by the structures of the hindbrain, which include the medulla,
pons, and cerebellum.
• The medulla controls various bodily functions involved in sustaining life, including heart rate,
blood pressure, and respiration.
• The pons serves various functions in regulating stages of sleep.
• The cerebellum serves as a control center in helping to coordinate physical movements.
• The midbrain also is involved in the control of some motor activities, especially those related to
fighting and sex.
• The forebrain evolved more recently than the hindbrain and midbrain and, therefore, is the site of
most sensory, emotional, and cognitive processes. These higher mental processes of the forebrain
are linked with the midbrain and hindbrain by the limbic system.
• The limbic system is made up of a variety of different brain structures that are central to the
regulation of emotion and basic learning processes.
• d- Spinal cord is along bundle of neurons that carries messages to and from the body to the brain
that is responsible for a very fast, life saving reflexes.
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