Lecture 1 Neurodevelopmental Disorders Flashcards
What is a neurodevelopmental disorder?
Disorders of a genetic or multifactorial origin that result in one or more specific cognitive deficits.
These deficits are present early in life and extend into adult life without showing relapse or remission.
What are the three stages of diagnosis?
- Referral - usually from GP or health visitor
- Formal Assessment by NHS - diagnosis usually made by clinical psychologist/geneticist
- Post diagnostic support - e.g. school support, SLT
What are some examples of disorders with an established genetic basis?
Down’s syndrome, Sotos syndrome
Outline features of down’s syndrome
Caused by presence of all or part of a third copy of chromosome 21
Most common chromosome abnormality in humans
Physical growth delays, particular set of facial characteristics, and intellectual disability
Outline features of Sotos syndrome
Mutations in the NSD1 gene
Physical overgrowth during first years of life
Often taller, heavier, have larger heads
Intellectual disabilities
What is a disorder with a less clear genetic basis and why?
ASD
1000s of genes are implicated
Unclear whether ASD is explained more by rare mutations or by rare combinations of common genetic variants
Currently no genetic test, diagnosis made on basis of behaviour
Why might ‘disorder’ be an appropriate term?
Acknowledges the impact of a disability
A potentially accurate description of individual/family experience
Not using the term may be seen as trivialisation
Why might the term ‘disorder’ NOT be appropriate?
Label that has negative connotations thus producing stigma
May cause others to be prejudiced
‘Condition’ may be a more accurate description
Neurodiversity should be valued
What is Neurodiversity?
An approach to learning and disability that suggests that diverse neurological conditions appear as a result of normal variations in the human genome
Should be recognised and respected as a social category
What are the different methodologies used for studying neurodevelopmental disorders?
- Population based prevalence studies
- Behavioural Observation
- Parent/Teacher questionnaire
- Behavioural experiments e.g. eye tracking
- Cognitive Neuroscience experiments e.g. fMRI, EEG
- Semi-structured interviews
What is the prevalence of Fragile X Syndrome?
1 in 4000 males, 1 in 6000 females
Less severe symptoms in females, the 2nd X chromosome seems to be somewhat protective
What is Fragile X Syndrome?
The most common form of inherited intellectual disability, typically diagnosed at 3-4 years
What is the cause of FXS?
An expansion of the CGG repeat at the beginning of the FMR-1 gene on the X chromosome
Individuals are either classed as having a full mutation, pre mutation or normal allele, based on the size of the CGG expanded region
The classification is identifiable via a DNA blood test
What is grey matter?
Contains cell bodies, dendrites & axon terminals of neurons, where all the synapses are
What is white matter?
Axons connecting different parts of the grey matter to each other
