Psychology - Abnormal

Types of biological studies for MDD

Kinship study:

Studies about family members. Used to investigate things like MDD and whether or not they are genetic (ppt and relative would then be the same) or environmental (ppt not similar to relative).

--> HOWEVER family often live near each other, so there's always an environmental similarity UNLESS they're reared apart

Twin study:

Studies about monozygotic (same egg, same sperm --> 100% genetically similar) and dizygotic (different egg, different sperm --> 50% similarity) twins. Used to investigate how much of MDD is due to environmental factors or genetic factors. Similarities in twins can be assumed to be genetic impacts, while differences in twins can be assumed to be environmental impacts.

Biological theory for MDD

5HTT gene:

Shorter 5HTT genes mean the person is more susceptible to stress-induced depression. This is because a shorter 5HTT gene means that fewer serotonin transporters are made, causing serotonin to be inefficiently uptaken. Since it takes longer for the serotonin to be taken up, it remains in the synaptic cleft and is eventually degraded by enzymes. As a result, there is less serotonin, making mood regulation more difficult.

Studies for the biological theory of MDD

Kendler et al (2006) - Correlational Swedish twin study

Weissman et al (2005) - Kinship study

Caspi et al (2003) - 5HTT

Kendler et al (2006)

A:

Replicate the findings that MDD is moderately heritable. Also investigate whether biological sex affected MDD, and what the genetic and environmental factors of MDD are.

P:

Correlational study of around 42,000 Swedish twins. They would have online structured interviews done on them by professional interviewers, where they were asked about their sad episodes and would also be assessed using the criteria of MDD.

F:

The study found that MDD was moderately heritable. Around 8000 twins had MDD. MDD was also more heritable for women than men. The genetic factors and environmental factors of MDD remained the same compared to the previous study done on 3 cohorts between 1900 and 1958.

C:

Some risk factors for MDD may be sex specific

Evaluation for Kendler et al (2006)

Strengths: Large sample size, findings generalisable to the Swedish population

Disadvantage: Difficult to draw conclusions because it is a correlational study

Weissman et al (2005)

A:

Investigate whether MDD is heritable between different generations

P:

Study took place over 20 years, 3 generations, with 161 ppt's. The study specifically looked at families at high and low risk of depression. The first ppt's came from an outpatient clinic that specialised in the treatment of mood disorders. Other ppt's were then taken from the local community, who did not have depression. The grandparents were interviewed, along with their own children. When the children grew up and had their own children, it allowed the study to continue onto the next generation. Their children were also interviewed by 1 child psychiatrist and 1 psychologist. Afterwards, the data was collected by researchers who were blind to previous tests, interviews and diagnoses. Method triangulation was used to increase the reliability of the findings.

F:

When parents and grandparents who showed symptoms of MDD, grandchildren were more likely to show symptoms of psychiatric disorders.

When grandparents and parents had MDD, the grandchild would have a higher risk of MDD

If grandparents didn't have MDD, but parents did, then the grandchild would not show any symptoms of MDD.

C:

It is likely that MDD is heritable, since the grandchild was more likely to have it if both grandparents and parents had MDD.

Evaluation for Weissman et al (2005)

Strength:

Disadvantage:

Caspi et al (2003)

Evaluation for Caspi et al (2003)

Strength:

Disadvantage:

Cognitive theory of MDD

MDD is caused by illogical thinking, and has 3 aspects to it:

1) Selective attention = Focusing on the negative aspect of an issue

2) Magnification = Placing too much importance on the issue

3) Overgeneralisation = Draw broad conclusions on the basis of this singular event

This illogical thinking could then lead to Beck's negative triad:

1) Negative trait = Depressed people have a negative view of themselves, the world, and the future

2) Negative schemas = Negative thoughts and beliefs triggered by earlier experiences, which can lead to the creation of negative schemas

- Ineptness = I always fail

- Self-blame = It's always my fault

- Negative self evaluation = I am worthless

3) Irrational thinking = Illogical thinking which are not based on reality or evidence but on emotions, biases, and past experiences

Studies for cognitive theory of MDD

Alloy et al (1999), Joiner et al (1999)

Alloy et al (1999):

A:

Investigate whether negative thinking styles can lead to the development of depression

P:

Around 400 college freshmen, with an average age of 20, were part of the sample. They were followed for 6 years. They did not have any other psychological disorders at the time, and did not show symptoms of depression either. Half of the sample did not have depression in the past, while the other half had depression before this. However, they did not show any symptoms. They first took a questionnaire that would measure their thinking styles and were sorted into either positive thinking styles or negative thinking styles. Interviews and questionnaires were used to measure their negative life events, cognitive thinking styles, and symptoms of depression. Researchers then compared the rate of depression between the two groups

F:

For the group that previously did not have depression, 17% of the negative thinking style group had it after 6 years, while only 1% of the positive thinking style group had it. For the group that previously had depression, 27% of the negative thinking styles had relapsed, while 6% of the positive thinking styles had relapsed.

C:

Negative thinking styles can lead to the development of depression

Evaluation for Alloy et al (1999)

Strength: Used data triangulation, which increases the credibility of the findings + Highly standardised test used to measure cognitive styles → High reliability

Disadvantage: Link between cognitive styles and depression more complex than the study proposes + Natural study → Difficult to establish causal relationship

Joiner et al (1999)

A:

Investigate whether or not anxious and depressive thinking can lead to the development of depressive symptoms

P:

Around 120 freshmen from a US state university taking part in an abnormal psychology class were part of the sample. They were tested using 3 assessments 2 weeks before their final mid-term exams and 2 weeks after. The 3 assessments include:

1) DAS = Measures thinking styles, including things such as need for validation, vulnerability, need for perfection etc... Students took this test during their mid-terms

2) CCL = Half of the test would measure automatic depressive thoughts, while the other half would measure anxious thoughts. Students took this test 2 weeks before and after the mid terms.

3) Beck's depression inventory (BDI) = Standardised test which would measure symptoms of depression. Students took this test 2 weeks before and after the mid terms.

F:

Students with high DAS score and failed their exams were more likely to score higher on the BDI test. However, if they had high DAS but passed their exams, it would not affect their BDI score.

Students with low DAS score, even if they failed their exams, would not have their BDI score affected.

CCL showed a high correlation between depressive thinking patterns and high BDI score.

There was no correlation between anxious thoughts and increase in BDI.

C:

Evaluation for Joiner et al (1999)

Strength:

Disadvantage:

Sociocultural theory of MDD

Diathesis stress model:

MDD is caused by a mixture of diathesis (biological vulnerability such as genetic predisposition or trauma occuring before the age of 5) and environmental stressors.

Studies for the sociocultural theory of MDD

Brown and Harris (1978), Chiao and Blizinski (2010)

Brown and Harris (1978)

A:

Investigate the social and environmental factors contributing to depression

P:

Around 460 women from South London had semi-structured interviews done with them on their daily lives and depressive episodes. They were asked about any difficulties or negative life events they had gone through. Afterwards, independent researchers would then rank the events based on severity.

F:

(37) 8% of women had depression. 4 out 8% of the women did not experience any adversity. Working-class women were also twice as likely to get depression compared to middle-class women. There were 3 main factors which affected the development of depression.

1) Protective factors = Protect against the development of depression (e.g. good relationship with husband, social support)

2) Vulnerable factors = Increase the risk of depression in combination with particularly stressful life events

- Top 4 include: losing a parent at a young age, having 3 children under 14, no job, and a lack of a confiding relationship.

3) Provoking factors/agents = Add to acute and ongoing stress. If the women had no social support, then it could lead to feelings of grief and hopelessness.

C:

Low social status leads to increased exposure to vulnerable factors and provoking agents, while higher social status leads to more exposure to protective factors and decreased exposure to provoking agents

Evaluation for Brown and Harris (1978)

Disadvantage: Sample not representative of all people across the world, as it is only women from South London

Correlational study → Causal relationship → Can't manipulate variables → Therefore, can't determine the extent to which sociocultural factors impact the aetiology of MDD

3rd factor that led to correlational relationship → Only the women with vulnerability developed MDD (4/37 did not have a stressful life event)

Chiao and Blizinski (2010)

A:

Investigate the cultural values of individualism and collectivism in the frequency of the 5HTT gene

P:

Investigated 50,000 ppts across 30 different cultures. Countries were sorted into different cultures based on Hofstede's individualism-collectivism scale. The global prevalence of mental disorders was taken from the WHO 2008 survey. Data was also taken from existing publications on the variation of 5HTT gene across the world.

F:

Countries that were individualistic had higher rates of psychological disorders compared to collectivist countries. This is because collectivist ideals and social harmony act as a preventative measure against it.

C:

Collectivist values served as a buffer against high rates of mental disorders

Evaluation for Chiao and Blizinski (2010)

Strength: Multicultural study, more generalisable findings

Disadvantage: Estimates of depression in collectivist countries may be vulnerable to response bias due to the stigmatisation of mental health issues, causing individuals to not report it or seek help (individuals expected to conform to social norms)

Prevelence rate of depression

3.8% of the population experiences depression

5% of adults have depression (6% women, 4% men)

280 million people total in the world have depression

5.7% of adults older than 60 years old

Depression is 50% more common among women than men

10% of women who are pregnant or have just given birth experience depression

75% of people in low and middle-income countries receive no treatment

Studies about the prevalence rate of depression

Abate (2013), Brown and Harris (1978)

Abate (2013)

A: Investigate the gender prevalence of depression

P: Analysed 31 studies between 2002 and 2013. There were around 20,000 patients of equal genders. They were measured using Beck's Depression Inventory and the DSM-IV.

F: Around 20% of males had depression. Around 30% of women had depression. 63% of women were more likely than men to get depression.

C: Women were more likely to get depression compared to men

Evaluation of Abate (2013)

Strength:

Large sample - Generalisable findings

Well established depression scales - Enhances validity and reliability of data

Disadvantage:

Didn't consider cultural differences in how depression is diagnosed or expressed in international data → Doesn't look at other contributing factors, only at gender → CONFOUNDING VARIABLE

Study does not discuss gender differences in symptom presentation (e.g. men may show depression through anger or substance use), leading to underdiagnosis → DSM-IV and Beck's don't measure this