ASD - Biological Explanations

Question 1

1 What is the amygdala?

Answer 1

2 almond shaped groups of 13 nuclei found in the temporal lobe which are apart of the limbic system,

Question 2

1 What is the amydala responsible for?

Answer 2

The perception of emotions (anger, fear etc) as well as controlling aggression

Question 3

1 What did Nordahl et al (2012) find?

Answer 3

The amygdala grows 6-9% faster during childhood in children with ASD
This early growth may lead to abnormalities

Question 4

1 What could abnormal development do?

Answer 4

Influence processes and lead to social and behavioural deficits including:
- Social perception
- Social behaviour
- Processing of social information
- ‘Eyes task’ research showing low amygdala activation

Question 5

1 Supporting research (personal space) for amygdala dysfunction?

Answer 5

Kennedy (2009) - SM case study - lacking the concept of ‘personal space’ so stood very close to other people

Question 6

1 Supporting research (primates) for amygdala dysfunction?
Ethical issues?

Answer 6

• Practical issues - difficult to generalise results due to differences
• Ethical concerns - need to follow 3Rs

Question 7

1 Inconsistent research for amygdala dysfunction?

Answer 7

Howard (2000) - increased size of the amygdala
Pierce (2001) - decreased size of amygdala

Question 8

1 Why is the amygdala dysfunction a partial explanation?

Answer 8

Deficits may not be directly caused by the amygdala
Those with dysfunction cannot process fear or anxiety normally - this ‘fearlessness’ may affect social functioning

Question 9

2 What did Peter Szatmari (1999) find?

Answer 9

There is a 0.11% chance of an individual developing ASD among the general population
There is 2.2% chance of an individual developing ASD if their sibling has it

Question 10

2 What did Bailey et al (1995) find?

Answer 10

• Concordance rate of 60% for MZ twins
• Concordance rate of 0% for DZ twins

Question 11

2 What did Bernier et al (2014) propose?

Answer 11

A gene mutation in CDH8 is linked with ASD as well as a higher chance of having childhood gastrointestinal disorders, a larger head and wide set eyes

Question 12

2 What is non-syndromic ASD?

Answer 12

ASD is the only disorder diagnosed

Question 12

2 What is syndromic ASD?

Answer 12

ASD occurs with some other condition which may have a genetic cause

Question 13

2 What condition co-occurs in syndromic ASD?
Symptoms?

Answer 13

Fragile X syndrome:
- Intellectual disabilities
- An unusually long face
- Protruding ears

Question 13

2 How is FXS caused?
How many?

Answer 13

A mutation in the FMR1 gene on the X chromosome
60% of those with FXS meet the diagnostic criteria for ASD

Question 14

2 Supporting research (concordance rates) for genetic explanation?

Answer 14

Colvert (2015) - used questionnaires, interviews and observations.
MZ - 77-99%
DZ - 22-65%

Question 15

2 Contradictory research for genetic explanation?

Answer 15

Hallmayer (2011) - heritability of ASD was only 55%. remaining 45% wass environmental

Question 16

2 Methodological issues for genetic explanations?

Answer 16

Joseph (2004) - MZ are more liekly to be brought up in similar conditions (friends/clothes). could explain higher concordance

Question 17

2 Why is genetic explanations a partial explanation?
Landrigan (2010)?

Answer 17

ASD cannot be entirely genetic. environmental factors in a diathesis stress model could be needed to fully explain the origin of ASD
Landrigan (2010) - toxic chemicals and viruses the mother is exposed to while carrying her baby plays a role in the development of ASD