When you are writing an essay on etiologies, keep it simple to begin with. Find one basic etiology (brain abnormalities, appraisals or socioeconomic status) and explain how and why that’s linked with PTSD. Use simple studies to begin with, and then later in your essay explore the interactions of bio, cog and socio-cultural influences.
Etiology – Socioeconomic status
A common finding in studies on PTSD is that there is a negative correlation between socioeconomic status and the risk of developing PTSD after a traumatic event. That is to say, the lower your socioeconomic status (e.g. the poorer you are) the more at risk you are for getting PTSD after experiencing a traumatic event. There are two possible explanations for this. One is cognitive (appraisals) and the other is biological (hippocampus) but both involve the interaction of multiple factors.
Socioeconomic status and appraisals:
The economic resources someone has to deal with trauma may affect their appraisals of the trauma and the situations afterwards. For example, if you are wealthy and you have property damaged in a natural disaster, you may feel like you have the resources to cope with the situation, including replacing damaged possessions and perhaps even being able to afford therapy. This will lead to positive appraisals. However, if you don’t have much money the impact may be greater and your ability to cope will be less, so you may have more negative cognitive appraisals of the event. This will increase the likelihood of developing PTSD.
- See this blog post for more details on the link between appraisals and PTSD.
Numerous studies have found that racial minorities are more prone to developing PTSD (especially in the US), which could be linked with socioeconomic status (as in many countries minority groups tend to have lower socioeconomic status).
People from low socioeconomic backgrounds (i.e. poor people) are more at risk for developing PTSD following a traumatic event. This could be because of how poverty affects appraisals, or how poverty affects the brain.
Key Study
Correlations between income and PTSD (Irish et al. 2011): This study’s aim was actually to understand gender differences in the development of PTSD. The study included 356 participants who had been in a series car accident. They found that women were more at risk for developing PTSD. They also found that differences in income between men and women had a significant effect on the risk of developing symptoms of PTSD.
Comparison of PTSD after a natural disaster (Garrison et al.’s (1995): The aim of this study was to investigate cross-cultural differences in the US after Hurricane Andrew in Florida. The participants were 350 black, Hispanic and white teenaged participants six months after the hurricane. Structured interviews were used to gather data, including symptoms of PTSD. The results showed that young women were more than three times as likely to develop PTSD than men (9% and 3%, respectively). They also showed higher levels of PTSD for black (8.3%) and Hispanic (6.1%) than for white participants. The results also showed that the number of stressful events experienced after the hurricane had a stronger correlation with PTSD than those experienced during the Hurricane itself. This is more evidence to suggest the role of appraisals of the consequences of the traumatic event in explaining PTSD. This could be explained by the differences in economic resources available to different racial groups. But there are limitations with this explanation (see critical thinking considerations).
Race and socioeconomic status are linked in the USA. This could explain some racial groups increased rates of PTSD after experiencing a traumatic event, like a hurricane. If you have plenty of money, your appraisals of the trauma will probably be more positive (I can cope. We can replace our lost goods). If you have less money, you’re more at risk for negative appraisals (e.g. “I’ve lost my home and I had no insurance, now where am I going to live?”)
Interactions of environment and the brain
Poverty and the hippocampus: Numerous studies have found correlations between poverty and brain development, particularly in the hippocampus, an area of the brain associated with learning, memory and PTSD. The stress caused by poverty could be shrinking the hippocampus because stress releases cortisol, and prolonged release of cortisol in the brain has been shown to damage hippocampal neurons (see Sapolsky et al. 1990). Adverse childhood experiences and childhood trauma can also affect the development of the amygdala, which is another part of the brain linked with increased risk of developing PTSD following exposure to trauma.
Similarly, parenting might be a mediating variable in this relationship. That is to say, parenting styles might explain why poverty is linked with brain development – poverty might increase stress levels, which affects how a parent interacts with their child, which can affect the stress levels of the child, which affects the hippocampus.
Read this blog post for more on how and why a small hippocampus and amygdala could be linked with PTSD.
Key study…
Poverty and brain development (Luby et al., 2013): The aim of this study was to see if poverty was correlated with brain development and to see if there were mediating variables related to stress and parenting that could explain this relationship. MRIs were used to measure correlations between poverty, stressful events and parenting styles with hippocampal volume in 145 children over a 10 year period. The results showed a negative correlation between lower socioeconomic status and hippocampal volume (poorer kids had smaller hippocampi). Socioeconomic status was also positively correlated with amygdala volume (lower status = smaller amygdalae).
Socioeconomic status is correlated with hippocampal volume – this could explain why it’s also a risk factor for developing PTSD.
They also found that parenting and stressful life events were mediating variables in this relationship. That is to say, poverty increased stress levels and affected parenting which had an effect on the hippocampus. The researchers measured the parent-child interactions by giving the child a small gift but telling them they must wait until their parent finishes completing a questionnaire. This is designed to stress the child and to test the patience of the parent. How the parent dealt with the nagging of the child was recorded by researchers standing behind a two-way mirror and interactions between child and parent are recorded. The more positive the parent-child interactions were during the waiting for the gift task, the higher the hippocampal volume. (Gilbertson et al. and Karl et al. can be used to make the direct link to PTSD).
Critical thinking considerations:
- There are some areas of uncertainty and assumptions being made with the above studies. For example, in Garrison’s study they never assessed appraisals or socioeconomic status – we are assuming there’s a link here. We are also assuming race correlated with socioeconomic status. While statistically this is true in Florida, does this affect the validity of the conclusions that can be made about this study?
- Besides socioeconomic status, what alternative explanations are there for differences in the prevalence of PTSD? For example, what other factors might affect the appraisal process, or development of the hippocampus?
- The above studies are conducted in the US. Do you think socioeconomic status will be correlated with PTSD across all cultures? Any reasons why this link may not apply to other cultures?
Exam tips:
- Numerous studies in this topic can be used in other topics, including Urry et al.’s study showing the localization of function of the vmPFC in cognitive reappraisal and Luby et al.’s study for neuroplasticity
Travis Dixon is an IB Psychology teacher, author, workshop leader, examiner and IA moderator.