Abnormal Psych

IB HL Psychology 2026

Karl et al. (2006) Aim

To see if brain structure is correlated with PTSD symptoms

Karl et al. (2006) Procedure/methods

Correlational study*; examined structural abnormalities of the hippocampus, amygdala, and other brain regions in people with PTSD; comparison with trauma-exposed and non-exposed control groups; secondary data gathered from 50 studies, all of which used MRI and DSMIV to diagnose symptoms of PTSD

Karl et al. (2006) Findings

The "strongest" correlation showed reduced hippocampal volume, although effect size was only 0.28 (closer to a medium effect); weak correlation was found between reduced amygdala volume and PTSD symptoms; studies on children showed a correlation between reduced frontal lobe volume and PTSD symptoms, but no link was found between hippocampal volume and PTSD in the group

Conclusion

abnormalities in amygdala size, hippocampus, and PFC could be etiologies of PTSD

Karl et al. (2006) Strengths

1. Large sample (many studies used) strengthens the conclusions about relationships between brain volume and PTSD
2. Use of a control group, allows baseline comparison

Karl et al. (2006) Limitations

1. Correlation doesn't equal causation and the strongest correlation is still weak
2. Bidirectionality problem with variables (genetics, age, SES, etc. could impact results)

Gilbertson et al. (2002) Aim

To investigate if low volume in the hippocampus is a symptom or etiology for PTSD

Gilbertson et al (2002) Procedure/methods

Correlational twin study using 34 pairs of identical twins with each pair containing a trauma-exposed twin; MRI scans conducted to measure hippocampal volume, each pair assessed based on trauma exposure and presence/absence of PTSD

Gilbertson et al (2002) Findings

The trauma-exposed twins that developed PTSD showed smaller hippocampal volumes compared to the non-PTSD twin; both groups displayed differences in hippocampal volume based on PTSD status

Conclusion

smaller hippocampal volume is an etiology of PTSD and lower hippocampal volume correlates with severity of PTSD symptoms

Gilbertson et al (2002) Strengths

1. Twin design controls for genetic and environmental factors which enhances validity of findings regarding hippocampal volume and PTSD
2. Biological understanding of PTSD

Gilbertson et al (2002) Limitations

1. Correlation doesn't equal causation therefore it is still uncertain whether low hippocampal volume causes PTSD or is rather a result of it
2. Small sample size may not be fully representative of broader population leading to low generalizability of findings

Urry et al. (2006) Aim

To investigate what areas of the brain are utilized during cognitive reappraisal, focusing on effects of the ventromedial prefrontal cortex on the amygdala

Urry et al. (2006) Procedure/methods

19 participants underwent fMRI while viewing emotional pictures and they were instructed to perform one of three tasks:

1. Amplify emotional response by imagining a worse outcome.
2. Reduce emotional response by imaging the situation wasn't real
3. Look at the picture and react naturally

Urry et al. (2006) Findings

The increase condition led to heightened amygdala activity, the decrease condition led to increased activation of vmPFC, and the more activity in the vmPFC the lower amygdala activity was during decrease condition

Urry et al. (2006) Strengths

1. True experimental design

Urry et al. (2006) Limitations

1. Small sample size

Hitchcock et al. (2015) Aim

To see if negative cognitive appraisals were correlated with the development of PTSD symptoms after a traumatic event

Hitchcock et al. (2015) Procedure/methods

Symptoms of PTSD measured in children exposed to a traumatic event within a month of the trauma and then again after 6 months; correlations examined between negative appraisals after the traumatic event and development of PTSD symptoms

Hitchcock et al. (2015) Findings

A moderate (but statistically significant) correlation found between negative appraisals and the severity of PTSD symptoms after 6 months Study concluded that negative cognitive appraisals can increase the likelihood of developing PTSD after exposure to trauma

Hitchcock et al. (2015) Strengths

The study highlights the importance of cognitive factors in the development of PTSD which suggests potential areas for therapeutic intervention

Hitchcock et al. (2015) Limitations

1. Correlational design

Irish et al. (2011) Aim

To understand gender differences in the development of PTSD

Irish et al (2011) Procedure/Methods

Correlational study 356 people who have been in a car accident in Ohio, USA Questionnaires used to gather data including CAPS; information collected on income levels, PTSD symptoms, severity of injuries, and perceived life threat

Irish et al. (2011) Results

Women were found to be at greater risk for developing PTSD and reported higher perceived life threat. A negative correlation was observed between income and PTSD symptoms; individuals with higher income reported fewer symptoms. Differences in income between men and women were identified as a contributing factor to the higher risk of PTSD symptoms in women. Study concluded that women and people from low SES backgrounds are at an increased risk for PTSD

Irish et al. (2011) Strengths

Large sample size Focus on real-life trauma Correlation with socioeconomic factors

Irish et al. (2011) Limitations

Correlational design Self reported data may introduce bias Confounding variables

Top down processing

information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations

Cognitive reappraisal

Regulating one's feelings about an experience by reinterpreting that experience or thinking about it in a different way.

vmPFC (ventromedial prefrontal cortex)

A neural area that has been found to be important for processing risk, fear, inhibiting emotional responses, cognitive evaluation of morality, empathy, and choosing between outcomes (cost-benefit).

ACC (anterior cingulate cortex)

Region of the brain involved in processing and controlling emotion, decision-making, monitoring for conflict/errors, assigning value to outcomes

Etiology

the cause of a disease or condition

PTSD

post traumatic stress disorder

MRI

a technique that uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of soft tissue; allows us to see structures within the brain

Biological Correlate

an identifiable link between a specific biological factor and a specific behavior

Anhedonia

inability to experience pleasure

Gray matter

a portion of the CNS consisting of cytons (cell bodies), their dendrites and synaptic connections

White matter

Whitish nervous tissue of the CNS consisting of neurons and their myelin sheaths.

Hippocampus

Region of the brain that helps process explicit memories for storage.

Amygdala

Region of the brain involved in memory and experiencing emotion, particularly fear and aggression.

Socioeconomic status (SES)

a measure of social class that is based on income, education, and occupation

Internal validity

the degree to which the effects observed in an experiment are due to the independent variable and not confounding variables

Multifaceted data collection

using multiple methods or sources of data to gather information

Early maladaptive schema model

States that schema formed early in life as a result of negative childhood experiences affect how we process negative life events.

Locus of control

the tendency for people to assume that they either have control or do not have control over events and consequences in their lives