Bio Explanations Of ASD Flashcards
What did Szatamari find in relation to ASD and genetics?
He combined data from studies to calculate an overall sibling risk. Shows the proportion of siblings of people diagnosed with ASD, that also meet criteria. Rate was 2.2%.
Without ASD siblings - 0.11%.
20x greater risk of getting ASD if a sibling has it.
Suggests some genetic component to onset of ASD when comparing siblings.
What did Bailey et al find in his genetic twin study for ASD?
They analysed data from the British Twin Study. Concordance rate for MZ twins was 60%, and DZ 0%. Researchers then widened definition of autistic behaviours and found 92% concordance for MZ, 10% for DZ.
This suggests strong genetic component in MZ twins for ASD.
What’s the difference between simplex and multiplex families?
Simplex families only have 1 member with ASD whereas multiplex families have more than 1 members of their family who are diagnosed with ASD or haven autistic traits but weren’t diagnosed.
How does ASD form in multiplex families vs simplex families?
Multiplex - genetic variation that’s inherited.
Vs
Simplex - ASD is caused by a ‘de novo’ mutation.
How does the ‘de novo’ mutation occur?
Genetic alteration that is present for the first time as a results of a variant in a germ cell of one of the parents, or a variant that arises in the fertilised egg itself during early embryogenesis.
What is a strength/weakness of the genetic explanation of ASD (supporting evidence)?
Szatamari (1991). However, made pre-2013 so based on old diagnostic criteria of ASD, low temporal validity.
What’s a strength/weakness of the genetic explanation of ASD (reductionist)?
Reduces ASD down to genes, in depth research. However incomplete as it ignores other factors. Too simple.
What’s a strength of the genetic explanation of ASD (scientific)?
Scientific evidence to support it. Credible, unfalsifiable, has scientific rigour.
What is the amygdala?
Part of limbic system.
Fear and emotion processing.
Implicated in memory processing.
Connections to prefrontal cortex, hippocampus, hypothalamus and other areas.
What did Nordahl find in relation to ASD and the amygdala?
From 2 years old, there is a larger growth in the amygdala volume in children with ASD (6-9%). There’s no difference in amygdala volume in teens/adults (ASD or not). Growth occurs earlier in ASD children and can lead to abnormalities in neural organisation of amygdala and damage its functioning.
Describe Baron-Cohen’s theory of the ‘social brain’.
As the amygdala has neural connections with the frontal cortex, abnormal development of amygdala in childhood is causal factor for social/behavioural deficits. So those with ASD have difficulties in understanding expression of emotions in other people.
Describe Baron-Cohen’s study of amygdala and ASD (eye test).
ASD adults were matched with control without ASD. Ps were presented with photographs that only showed the eye area of people making different facial expressions and asked to identify the expression shown. Brain activity was measured with MRI.
Those with ASD performed worse than controls. MRI showed left amygdala wasn’t activated in the ASD ps at all but was strongly activated in the controls. So left amygdala is involved when inferring emotional state from facial expressions, impaired in ASD.
Give a strength/weakness of the amygdala explanation of ASD (reductionist).
Reducing behaviour down to amygdala dysfunction. Can study in depth, however it’s incomplete and too simple.
Give a strength/weakness of the amygdala explanation of ASD (deterministic).
Behaviour is predetermined by biology (amygdala). This makes behaviour predictable. However, it can make people feel powerless.
Give a strength/weakness of the amygdala explanation of ASD (scientific).
Use of MRI scans. Objective evidence, makes the explanation credible, has scientific rigour. However, ethical issues of ASD people having brain scans (claustrophobia/tight spaces).
Apply the oxytocin method of modifying to amygdala dysfunction.
If research says that amygdala dysfunction is a cause of ASD behaviours related to social behaviours and emotional processing, then improving the function of the amygdala may help to redue these. Intranasal oxytocin has been found to enter brain effectively and work to increase levels in limbic system. Studies show that when oxytocin is taken (ASD ps) they do better on social behaviour tests.
