Slides in this set

Slide 1

Preview of page 1

Models of Abnormality…read more

Slide 2

Preview of page 2

This model assumes that behaviour can be explained in terms of
biological mechanisms such as hormones, neurotransmitters,
brain activity and influences inherited by genes.
These causes can be linked to bodily
a) Genes:
Kendler et al
A unit of inheritance from parents, meaning a (1985) found that
predisposition. relatives of
Biochemistry: Schizophrenics
are 18x more
Certain neurotransmitters contribute to likely to be
disorders ­ such as Schizophrenia and Dopamine. diagnosed with
Post mortem-examinations show that
Schizophrenics have enlarged ventricles.
And linked to inheritance:
This can be seen through concordance rates ­
especially in twins if they have been bought up
separately meaning they've had different
environmental factors.…read more

Slide 3

Preview of page 3

Abnormality is caused by physical factors.
The biological model assumes that all mental disorders are related to a change
in the body. Mental disorders are like physical disorders (meaning they are like
illnesses). Such changes or illnesses may be caused by one of four factors:
Genetic Inheritance:
Abnormalities in the brain are sometimes the result of genetic inheritance. A
way of investigating this is studying identical twins and comparing them to see
if one twin has the disorder, the other has it as well, creating a concordance rate
(seeing to which extent two individuals are similar in terms of a particular trait).
Genes leading to abnormal biochemistry / neuroanatomy:
Genes tell the body how to function, and determine the levels of hormones and
neurotransmitters in the brain (biochemistry). High levels of serotonin can be
linked to anxiety where as low levels can be linked to depression. Genes also
determine brain structure (neuroanatomy) research has also shown
schizophrenics have enlarged ventricles in the brain, indicating shrinkage of
brain tissue.
Viral infection:
Research suggests that some disorders may be related to exposure to certain
viruses in the womb. Torrey (2001) found that the mothers of many
schizophrenics had contracted a particular strain of flu. The virus may enter
the unborn child's brain, remaining dormant until puberty, then it is activated…read more

Slide 4

Preview of page 4

Humane or Inhumane?
When the biological model emerged in the 18th century it led to more humane
treatment of mentally ill patients. Until then mental illness was blamed on evil in
the individual. The medical model then meant that the illness was potentially
treatable. However Thomas Szasz (1972) argued that mental illness did not have a
physical basis and should not be thought of in the same way, he argued that
mental illness was `invented' as a form of social control.
Cause and Effect?
The available evidence does not support a simple cause and effect link between
mental illness and brain chemistry. An example being Schizophrenia being
commonly associated with excess of the brain neurotransmitter dopamine.
However some studies of Schizophrenics have shown reduced levels of dopamine
in some brain tissues. Meaning there may be simultaneous excesses and
deficiencies in different parts of the brain.
Inconclusive evidence
There is no evidence that mental disorders are caused purely by genetic
inheritance ­ concordance rates are never 100%. Gottesman and Shields (1976)
studied 5 pairs of twins and looked for concordance rates in Schizophrenia. They
found genetically identical twins concordance rate was around 50%. Showing
what individuals inherit is likely to be a susceptibility to the disorder.…read more

Slide 5

Preview of page 5

If patients fare better when given a drug which alters brain chemistry, it
shows the importance of biochemical changes for this disorder. Kirsch et al
(2002) found that in 38 studies of antidepressants, patients who were
receiving a placebo fared almost as well as the real drugs.
Correlational Studies
It's impractical and immoral to carry out experiments to test for genetic
inheritance, psychologists rely on correlations to investigate the
relationship between heredity and the development of mental disorders.
Correlational studies provide a comparison of mental disorders but do not
demonstrate cause and effect.…read more

Slide 6

Preview of page 6

Antipsychotic Drugs
The conventional antipsychotics are used primarily to combat the positive
symptoms of Schizophrenia. These drugs block the action of dopamine by
binding to, but not stimulating dopamine receptors.
The atypical antipsychotic drugs act by
temporarily occupying the dopamine
receptors and then rapidly detaching
themselves to allow normal dopamine
transmission. This may explain why the
atypical antipsychotics have lower levels of
side effects compared to conventional
antipsychotics. Drugs
Depression is thought to be due to
insufficient amounts of neurotransmitters
such as serotonin. Antidepressants work by
reducing the rate of re-absorption in
neurotransmitters or by blocking the enzyme
which breaks them down. Both of these
mechanisms increase the amount of
neurotransmitters available to excite
neighbouring cells.…read more

Slide 7

Preview of page 7
Preview of page 7

Slide 8

Preview of page 8
Preview of page 8

Slide 9

Preview of page 9
Preview of page 9


No comments have yet been made

Similar Psychology resources:

See all Psychology resources »