Download Evaluation of Etiology

Depression
Evaluation of Ethiology
Genetic Cause
Strengths
• Twin studies have been highly reliable in their results.
• Modern research has allowed us to actually locate the genetic variations
using very large sample sizes.
• Modern research recognizes the interaction of environmental and
biological factors.
Limitations
• Correlational studies do not establish a causal relationship.
• In twin studies there is a problem with population validity - samples are so
small that there is difficulty in generalising results. In addition, the life of a
twin may be different from the experience of the general population.
• It is impossible to isolate variables and to separate out social factors.
• The argument is reductionist in nature and does not account for the
variations in the symptomology of depression.
• It is not yet clear how the 11 genetic markers interact.
Biochemical
Strengths
• There are several longitudinal case studies and animal research
which supports the theories.
• Practical application of the theories have led to successful drug
treatments that have improved people's lives.
Limitations
• Correlational research means that causation cannot be
established and bidirectional ambiguity cannot be resolved.
• The Treatment Aetiology fallacy - that is, the mistaken notion that
the success of a given form of treatment reveals the cause of the
disorder.
• Biological explanations cannot explain the range of symptoms
associated with depression. There may be cultural and cognitive
factors as well. The biological explanation can be seen as a
reductionist approach to explain a complex human behaviour.
Beck’s Theory
One of the strengths of the theory is that there is significant evidence that
Beck has accurately described the thinking patterns of depressed patients.
These include:
• Beck's own clinical observations.
• Self-report questionnaires given to depressed patients.
• Laboratory studies on memory bias
Studies of memory bias were carried out by Ruiz-Caballero & Gonzalez
(1994) on depressed and non-depressed college students.
• They gave participants a word-stem completion task to see whether in
solving the task they would recall words with a positive or negative
connotation.
• The results indicated that depressed participants showed a memory bias
for negative words.
In general, research shows that when depressed individuals are given lists of
words that vary in emotional content, they tend to recall more negative
words than do non-depressed individuals.
Beck’s Theory
Another strength of the theory is that highly successful therapy has been
developed based on this theory which has led to improvement in a large
number of patients.
One of the limitations of the theory is the problem of bidirectional ambiguity.
Hammen argues that negative cognitions may be the result of rather than
the cause of depressed moods.
• Beck himself argues that the relationship is bidirectional: depression can
make thinking more negative, and negative thinking can probably cause
and certainly worsen depression.
The best way to resolve this issue is to carry out prospective case studies.
These, however, are difficult to organize. One study by Joiner et al (1999)
gave a questionnaire to university students before mid-term exams. Those
who had negative thoughts before the exam who ended up doing poorly
showed an increase in depressive symptoms. However, those that did well,
did not. This shows that cognition must also interact with environmental
stimuli in order to result in depressive behaviour.
Vulnerability Model
There has been extensive research on the role of stress on depression. The use of
prospective longitudinal research has led researchers to believe that there is a cause
and effect relationship. Often socio-cultural studies engage in method as well as
researcher triangulation in order to increase the validity of the findings.
Vulnerability models have been used to explain both gender and class differences in
the prevalence of depression.
One of the limitations is how we measure "stress."
• Holmes & Rahe's Social Readjustment Rating Scale has ranked the stress levels of
different life events to help determine how much stress an individual has
experienced in the past year.
• Although this assessment is frequently used, there is evidence that shows that
smaller stressors - what Kanner (1981) called "hassles" - may play an even more
significant role in one's overall mental health. This could be because larger life
events can eventually be interpreted and seen as having significance or meaning,
whereas the hassles are seen as an irritation and without purpose.
As with the other levels of analysis, it is difficult to argue social stressors are the cause of
depression. It is only with the interaction of biological factors that the stressors appear
to lead to the disorder. It is difficult, but not impossible, to carry out research that
examines the interaction of biological, cognitive and socio-cultural factors.