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
What are the differences noticeable in the brain of FXS at 1-3 years old?
Voxel-wise grey and white matter volumes comparison
enlarged grey matter volume in the caudate, thalamus and fusiform gyri
What are the physical features of FXS?
Long, narrow face
Prominent jaw and ears
Flat feet
What are the common ‘ADHD-related’ features in FXS?
Short attention span Distractibility Impulsiveness Restlessness Overactivity Co-morbidity of 54-59%
What are the common ‘ASD-related’ features in FXS?
Sensory problems Social difficulties Emotional difficulties Communication difficulties Co-morbidity of 25-80% Also co-morbid with epilepsy
What are relative strengths in FXS?
Imitation
Visual learning
Personable (sensitive, sense of humour)
What is the cognitive and behavioural profile for males with FXS?
Mean IQ 40
Communication and social impairment
Hyperactivity, inattention, impulsivity and hyperarousal
What is the cognitive and behavioural profile for females with FXS?
IQ 70+
Social difficulties
Emotional, anxiety, depression
What are the first signs of FXS?
Sensory-motor atypicalities at 9-12 months Decreased object play Increased leg stereotypes Atypical posture Prolonged visual attention to objects Missing milestones
How is adaptive behaviour measured?
via Vineland Adaptive Behaviour Scales
Assessed ‘real life skills’ and ‘independence’
Semi-structured parent interview
Positive environmental influences may act as protective factors e.g. parenting skill, BUT IQ was the strongest predictor of outcomes
What is the causal model?
A framework that incorporates all three biological, cognitive and behavioural levels as well as environmental factors
Aims to provide full causal explanations for ND disorders, incorporating developmental aspects to allow evaluation of different competing causal accounts for specific disorders
What can studies of atypical development help to do?
They can help us to understand the mechanisms behind successful development
Why do children recover faster and better from brain damage compared to adults?
Because the plasticity of the brain is greater in children than in adults.
Why might fMRIs cause difficulties for people with disorders?
Have to stay still for a long time in confined spaces, may cause difficulties for individuals with high anxiety or hyperactivity
What makes identifying the cause of neurodevelopmental disorders difficult?
Variability and co-morbidity