Psychology Paper, Etiologies for Depression

Question 1

Caseras et al.

Answer 1

Aim: To investigate whether there is a difference between how depressed and non-depressed participants pay attention to positive and negative stimuli
Participants: 43 participants recruited through a university website

Procedure:
- Initially, the participants would be evaluated for depressive symptoms using the ‘Becks depression inventory’. Based on these results, the participants would be sorted into either the depressed group or the non-depressed group
- Participants were then put through a standardised procedure where they were shown 32 pairs of images. Each pair of images would be shown for 3 seconds, and the images would have either a positive, negative, or neutral connotation.
- Whilst viewing the images, the researchers utilised eye-tracking technology to monitor the gaze duration of the participants to either image, and to identify which image the participant initially looked at

Results:
- It was observed that the participants in the ‘depressed’ group would have longer gaze duration on the images which were negative stimuli
- There was no difference seen in which image was initially looked upon between the two groups
- The results imply that participant’s in the ‘depressed’ condition struggled to shift their attention away from the images of negative stimuli

Conclusion: The results credit that negative attention bias may be a potential factor which contributes to the development of depression

Evaluation:
1. Strengths
- Objective measurements
- Standardised and valid measurement system used (Becks depression inventory)
- Standardised procedure and experiment

2. Weaknesses:
   - Small sample size
   - Experimenter bias when it comes to determining whether the images were positive or negative stimuli
   - Low generalisability
   - Only a correlational relationship identified
   - Low ecological validity

Question 2

Kivela et al

Answer 2

Aim: To explore how different social factors may predict depression in elderly people

Procedure:
- Participants were taken from a clinical study in 1984 who were aged 61 or older
- Participants in this study who were assessed to be not depressed using a DSM-III criteria were examined in a follow-up study in 1989-1990 (total participant number of 679)
- Questionnaires were used to measure social factors and significant life events that occurred between 1984 and 1989. The researchers then compared the two groups of depressed and anon depressed participants in 1984-1990

Results:
- in 1989 depression was diagnosed in 8.2% of men and 9.3% of women
1. For men, indicators of depression include:P
- Poor relationship with their spouse.
- A negative change in their relationship with their spouse or neighbours.
- Losing their mother before the age of 20.
- A grandchild going through a divorce.
- Moving into institutional care.
- Alcohol problems in someone close to them.
2. For women, indicators of depression include:
- Losing their father before the age of 20.
- Low involvement in religious activities.
- Worsening relationships with neighbours.
- A decrease in social participation during the follow-up period.
- Alcohol problems in someone close to them.
- Living only with their husband, without other people in the household.

Conclusion:
- Social factors and changes in social relationships can help predict the development of depression in older adults. There are also differences between men and women in how social factors influence depression, likely linked to how they experience marital stress.

Evaluation:
1. Strengths:
- Longitudinal
- DSM III criteria used to initially assess for depression
- large sample size of 679 participants
- Participants included both men and women

2. Weaknesses
   - Sample size was only limited to a population in Finland
   - Self-reporting bias

Question 3

Alloy et al.

Answer 3

Aim: To investigate whether a negative or positive cognitive style in freshman could influence the development of depressive symptoms
Participants: Freshman who were initially not depressed

Procedure:
- Initially, the participants answered a questionnaire which would determine the cognitive style of the participant. Based on the results, the participants would either be allocated to the high-risk group (negative cognitive style), or the low-risk group (positive cognitive style)
- Then, over a period of 5.5 years, the researchers would utilise self-reported measures and structured interviews to assess the mental health of the participants over time.

Results:
- In the initial 2.5 year period, it was observed that the participants in the high-risk group were more likely to develop major depressive disorder when compared to the low-risk group (17% to 1% respectively)
- In addition, it was also observed that participants in the high-risk group would also be more likely to develop suicidal thoughts than the low-risk group (28% to 13% respectively)

Conclusion: The results of this study suggest that one’s negative cognitive style may be a contributing factor in the development of Major depressive disorder

Evaluation:
1. Strengths:
- Longitudinal
- High ecological validity (no variables manipulated)
- Structured interviews and standardised questionairs contributed to the validity of the study

2. Weaknesses:
   - Low internal validity to no variables being controlled
   - Self - reported measures
   - Maturation effect (over time variables may have changed such as the cognitive style of the participants)
   - Correlational only

Question 4

Kivela et al.

Answer 4

Aim: To investigate the role which genetics play in the development of Major Depressive Disorder (MDD)
Participants: 15,493 complete twin pairs which were registered in the National Swedish Twin Registry. Only twins who’s zygoticy which could be confirmed were used.

Procedure:
- The researchers had conducted telephone interviews with all participants in order to assess for depression between 1998-2003. A modified DSM-IV criteria was used to measure/assess for depression.
- In addition, the interview would also ask the twins for details of the ‘shared twin environment’ and their ‘individual specific environment’ in order to determine the role that the environment may have played in the development of MDD

Results:
- 8056 twins met the criteria to be diagnosed with MDD at some point in their life
- The coordinance rates of MDD was significantly higher in female twin pairs than male twin pairs
- The correlation for MDD was higher in monozygotic twins than dizygotic twins
- There was no significant correlation between the amount of years the twins shared together and the development of MDD
- There was no difference seen in the role of gene-environmental factors in all three cohorts born between 1900-1958
- The overall heritability for MDD was given as 0.38

Conclusion: The heritability in MDD is significant higher in women than men, and that the genes specific to the development of MDD may be sex-linked. The heritability of MDD of 0.38 also aligns with other studies.

Evaluation:
1. Strengths
- Large sample size
- Standardised and validated modified DSM-IV criteria used
- Cohorts of twins spanned multiple generations which contributes to generalizability
- Research aligned with other studies
- No control variables

2. Weaknesses
   - Self-reported bias
   - Correlational only
   - Limited to twins in the Swedish twin registry
   - Interviewer bias

Question 5

Kessler and Bromet

Answer 5

Aim: To investigate the prevalence rates of depression across cultures

Method: Kessler and Bromet was a meta analysis where the results of numerous epidemiological surveys on the prevalence rate of depression was analysed. The surveys analysed would be of epidemiological studies from various countries & cultures.

Results:
- MDD was found to be common across all cultures involved in the analysis
- The lifetime prevalence rate of MDD varied greatly across countries, from 16.9% in the USA to 1% in the Czech Republic
- The 12-month prevalence rate of MDD also varied greatly across countries, from 10% in the USA to 0.3% in the Czech Republic
- The average age onset of MDD was similar across countries. E.g. the average age of onset for MDD in high-income countries was 25.7 years, whilst it being 24 years for medium-low income countries
- The social-demographic factors of MDD were also similar across countries, with women generally being twice as more likely to developing MDD than men

Conclusion:
- The prevalence rates of MDD varied greatly across countries, this was attributed to several factors:
1. The difference in classification systems used
2. The difference in how symptoms are measured
3. The sample of the population taken
4. The actual prevalence rates of MDD across countries
- The prevalence rates of MDD was found to be higher in more wealthier countries, and this was attributed to the fact of income differences in those countries, however, more research is required

Evaluation:
1. Strengths
- High statistical rigour due to it being a meta-analysis
- Large sample size
- Strong generalisability
- Reduced bias from individual studies

2. Weaknesses:
   - Variation in quality of studies
   - Comparability issues (studies may differ in method, definitions, or participants which make them hard to compare)

Question 6

Ferrari et al

Answer 6

Aim: to estimate and develop an understanding of the global prevalence and incident rates of Major Depressive Disorder (MDD)

Method: The study was a meta-analysis which had analysed several databases on the prevalence rates of MDD across numerous samples and populations. The Dismod-MR model was used to study the epidemiology of MDD.

Results:
- In 2010, it was estimated that roughly 298 million people had MDD at any given time.
- The largest group affected by MDD were those aged 25-34
- The prevalence of MDD was similar to that in 1998, however, more women were affected than men (5.5% to 3.2%)

Evaluation:
1. Strengths:
- High statistical Rigour with the study being a meta analysis
- High generalisability
- Large Sample size
- Minimizes biases present in one study/database

2. Weaknesses:
   - Issues with comparability of studies (different definitions, measures, populations etc)
   - Differences in quality of databases
   - Overgeneralization, (analysing multiple databases and making general assumptions of the global prevalence of MDD may oversimplify more complex trends)

Question 7

Caspi et al.

Answer 7

Aim: To investigate whether there is a gene-environment interaction for the mutation of the serotonin transporter gene 5-HTT
Participants: 847 New Zealand 26-year-old whom have been previously assessed for mental health every other year until the age of 21

Procedure:
- Initially, the participants were split into 3 groups based on their serotonin transporter gene 5-HTT alleles
- Group 1: 2 short alleles, Group 2: 1 short and 1 long allele,
Group 3: 2 long alleles
- The participants were then asked to fill out a ‘stressful life-event’ questionnaire, which asked them on the frequency of different stressful events which had occurred between the age of 21 and 26.
- These events included topics such as relationships and finance
- The participants were also assessed for depression

Results:
- Participants with one or more short alleles of the serotonin transporter gene 5-HTT would display more symptoms of depression and suicidal idealisation in response to stressful life events when compared to participants with 2 long alleles
- This trend was more apparent with the more stressful life events

Conclusion: The inheritance of a short allele for the serotonin transporter gene 5-HTT in itself was not enough to warrant depression, however, would make an individual more dispositioned to displaying depressive symptoms when interacting with stressful life events

Evaluation:
1. Strengths
- No variables were manipulated
- Large sample of 847 participants
- Standardised questionnaire used

2. Weaknesses
   - Application limited only to 26 New Zealanders
   - correlational only
   - Self reporting bias
   - Questionnaires only give a limited scope of stressful life events experienced