(Hopefully) All Psychology SL Paper 2 Studies

Gilbertson et al. (2002): Aim

To investigate whether low hippocampal volume is a symptom or etiology of PTSD.

Gilbertson et al. (2002): Method

- case-controlled study on 34-sets of identical (monozygotic) twins.

- monozygotic twins have 100% of their DNA in common.

- if raised in the same environment they've probably had similar experiences.

- assume that if these twins were then sent to war their hippocampi would be the same in terms of structure and function.

- two different types of identical twins.

- one set of twins, where only one of them has gone to war, and developed PTSD (a trauma exposed twin) and the other twin who hasn't been to war and doesn't have PTSD (trauma unexposed).

- compared with a second set of twins.

- second set of twins is the same as the first, except the twin that went away to war (trauma exposed) did not develop PTSD.

Gilbertson et al. (2002): Results

- trauma unexposed twins of veterans with PTSD had smaller hippocampal volumes compared to unexposed twins of veterans without PTSD.

- MRI results show the correlation between PTSD in veterans and hippocampal volume.

Gilbertson et al. (2002): Conclusion

- important comparison to make here is between the two twins who didn't go away to war (trauma unexposed).

- co-twin of the PTSD patient has a smaller hippocampus compared to the co-twin of the non-PTSD veteran

- suggests that the low hippocampal volume is a factor that increases the vulnerability to developing PTSD as a result of exposure to trauma.

- suggests genetics and hippocampal abnormality are possible etiologies and biological explanations of PTSD symptoms related to memory.

Karl et al

Conducted a meta-analysis of MRI studies on patients with PTSD by looking at 50 studies and found the strongest correlation in the brain and PTSD had to do with reduced hippocampal volume. Also showed a correlation between reduced amygdala vulume and PTSD symptoms.

Gilbertson

Did a case-control study of hippocampal volume and PTSD by looking at twin pairs. In each pair there was a twin who went to war and one who didn't. In one group the twin who went to war developed PTSD. The results showed that both twins in the PTSD group had 10% smaller hippocampi. This is bi-directional result, did a small hippocampus cause PTSD or did PTSD cause the smaller hippocampus.

Irish et al

Studied correlations between income and PTSD by looking at 356 participants who had been in car accidents and found women were more at risk in developing PTSD as well as a substantial economic difference in the women who developed it

Garrison et al

Studied cross-cultural difference in the US of developing PTSD after a natural disaster by studying participants in Florida after Hurricane Andrew. Found through structured interviews that young women were 3X more likely to develop PTSD and Higher levels for Blacks (8.3%) AND Hispanics (6.1%)

Irish et al. (2011)

- included 356 participants who had been in a serious car accident

- found that women were more at risk for developing PTSD

- found that differences in income between men and women had a significant effect on the risk of developing symptoms of PTSD

AIM (Garrison)

To investigate the cross-cultural differences in PTSD symptoms after Hurricane Andrew in Florida

PROCEDURE (Garrison)

structured interviews:

- disaster experience

- emotional reactions

- disaster-related losses

- lifetime exposure to traumatic events

- recent stressful experiences

- psychiatric symptomatology

RESULTS (Garrison)

- roughly 9% of females and 3% of males met the criteria for PTSD

- the number of stressful events experienced after the disaster (which could be related to the ability to cope with the damage) had a stronger correlation with PTSD symptoms than the original hurricane experience itself

RESULTS (prevalence) (Garrison)

PTSD rates were highest among black people and Hispanics

CONCLUSIONS (prevalence) (Garrison)

one possible explanation for the increased prevalence rates could be economic disparity between racial groups

Ratzer et al (2014) research method

Natural experiment

Ratzer et al (2014) Aim

Investigate accident victims to see if the level of locus of control would be a predictor of PTSD

Ratzer et al (2014) Procedure

Information on participants' injury severity and ICU treatment were obtained through medical records

Participants were tested on levels of PTSD and locus of control

Demographic information, measures of acute stress symptoms, experienced social support, coping style, sense of coherence and locus of control were assessed within one month of the participant's accidents.

At the 6 month follow up PTSD was assessed with the Harvard trauma questionnaire.

Ratzer et al (2014) Results

19.2% of participants developed PTSD symptoms over 6 months and there was a significant correlation between those with an external locus of control and the onset of these symptoms.

Ratzer et al (2014) Evaluation limitations

Low validity as participants were classified to have PTSD based on the results of the questionnaire which is less reliable as a clinical diagnosis.

Traumas of events that were not related to the investigated injuries may have contributed to the onset of PTSD in participants, acting as an extraneous variable with reduces the accuracy of the found relationship between the locus of control and PTSD.

Jenness et al (2016)

A study that studied the relationship between cognitive distortions and the development of PTSD symptoms following a terrorist attack.

Which of the following statements accurately represents the results of this study?

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People with a high degree of media exposure to the attack are more likely to develop PTSD symptoms, if they also engage in a high degree of catastrophizing