Explaining an etiology of a disorder can be quite tricky for some students because they focus on the disorder in general. But in order to have a really effective explanation you’re better to focus on specific symptoms.


A three step approach to explaining an etiology

When learning an etiology or planning an exam answer, you can follow these three simple steps:

  1. Identify the etiology (the variable)
  2. Identify the symptom/s (the behaviour)
  3. Explain how the etiology might cause the symptom

After you’ve figured out how to explain the etiology, the next step is to be able to use evidence to support your argument!

NB: 1 and 2 aren’t necessarily in that order.

Explaining an etiology is just explaining how a variable influences behaviour. This is why you can use the same concepts and research in Paper 2 and Paper 1.


Easy example: PTSD – hippocampus and memory

  1. Etiology = low  volume in the hippocampus
  2. Symptoms = loss of memory of the trauma (and other memory problems)
  3. Explanation…

A common finding in people with PTSD is that they have low volume in their hippocampus. This could be an etiology as their memory might be impaired because the hippocampus plays a role in the consolidation of memory – transferring information from our short-term store (STS to our long-term store (LTS). If we have reduced volume in our hippocampus the ability to do this might be affected. This means that when someone experiences a traumatic event the hippocampus might not be able to transfer the memories of the event from the STS to the LTS, which is why they can’t remember details of the event.

Evidence: Gilbertson et al.’s case-control study suggests that low hippocampal volume (and genetics) is an etiology of PTSD, not a symptom (Dixon, pg 230-32). (Link to original study).

Image result for hippocampus
You could write an excellent answer that includes an explanation of the hippocampus as an etiology. But be sure to use evidence to support your argument!

Advanced example: PTSD – vmPFC and increased emotional arousal

  1. Etiology = reduced function in the ventromedial prefrontal cortex (vmPFC)
  2. Symptoms = increased emotional arousal
  3. Explanation…

A common finding in people with PTSD is their vmPFC is hypo-responsive and has reduced function. This could explain why people with PTSD may experience increased emotional arousal. This is because the vmPFC down-regulates emotion generated in the amygdala. People with PTSD may have conditioned responses to fearful stimuli (e.g. fireworks for a veteran) and this would trigger their amygdala, which activates the stress response and increases emotional arousal. The vmPFC, however, can help the cognitive processes necessary to regulate this reactivity of the amygdala. If someone has poor function in this part of the brain they can’t perform these cognitive reappraisals and so their emotional arousal will stay elevated. Similarly, the vmPFC plays a role in fear extinction: the ability to lose the conditioned fear. With poor function the fear extinction might not occur and so the conditioned response to environmental stimuli might continue for a long time after the trauma, resulting in continual activation of the amygdala and the stress response, thus causing increased emotional arousal. 

Evidence: Urry et al.’s study on health participants cognitive reappraisals and relationships between the amygdala and the PFC (Dixon, pg. 234-5) (Link to original article).

Image result for amygdala
An excellent explanation of PTSD could include how the amygdala, vmPFC and cognition are all related in the symptoms of increased emotional arousal.

You can see that this is a more advanced explanation because it includes the interaction of biology and cognition. This has the advantage, however, of allowing you to use this explanation in response to a question that directly asks for a biology etiology or a cognitive one. You simply  change the focus from the vmPFC to cognitive reappraisals and explain how the inability to reappraise images in a way that reduces arousal could explain symptoms.


A disorder is simply a collection of symptoms. There’s no way we can explain every symptom just by focusing on specific etiologies. This is why it’s better to identify specific symptoms for your explanation. A good essay answer would identify the fact that their explanation is limited and might even outline some of the symptoms that aren’t explained by the etiology identified in the answer.


While the above answers might seem complex, if you’re keeping up with the lessons in the student’s guide you should find them pretty easy to comprehend.