DEV Lecture 9 - Neurodiversity and Developmental Disorders

Neurodiversity and Developmental Disorders

• This lecture discusses neurodiversity and developmental disorders, focusing on autism, Williams Syndrome, and Down Syndrome, with an emphasis on their overlaps and differences.

Defining Terms

• Developmental disorders typically use the framework of symptoms, causes, and treatments.
• Neurodiversity highlights individual variations and societal roles and norms.
• Psychology has historically concentrated on the former, using the developmental disorder framework.

Developmental Disorders

• Onset happens during the developmental period, usually before school age.
• Effects can be specific to one domain or global deficits across multiple areas.
• High rates of co-occurrence are seen, for example, ADHD commonly co-occurs.
• Diagnoses consider excesses, such as overactive behaviors, and deficits.

Autism and ASD

• The APA and DSM (2013) refers to ASD as an umbrella term including autism, Pervasive Developmental Disorder – Not Otherwise Specified (PDD-NOS), and Asperger syndrome.
• It was first described by Kanner in 1943.
• It is relatively common, affecting 1 in 100 (Baird, 2007) or even 1 in 54 (CDC).

Autism Knowledge

• Autism is present across the lifespan.
• Autism is present across all IQ levels.
• More males receive a diagnosis than females.
• Profiles significantly vary, diagnosis results from both deficits in communication and repetitive behaviors.

Spiky Profiles

• The name "Spiky" refers to the difference or magnification between specific strengths and weaknesses.
• High peaks and low troughs manifest the differences between strengths and weaknesses.
• The expression of strengths and weaknesses varies over time, and by skill.
• This is used to identify individual needs, like support methods in a general environment.

Communication Difficulties

• There are persistent difficulties in social communication and interaction.
• Social-emotional reciprocity is one factor, ranging from abnormal social approach and failure of normal back-and-forth conversation.
• Also reduced is sharing of interests, emotions, or affect, and failure to start or respond to social interactions.
• Also of concern are using nonverbal communicative behaviors for social interaction, such as poorly integrated verbal and nonverbal communication or abnormalities in eye contact and body language.

Restricted or Repetitive Behavior

• Stereotyped or repetitive movements, use of objects, or speech like motor stereotypes.
• There is insistence on sameness or rigid patterns like extreme distress at small changes or transition difficulties.
• Restricted, fixated interests emerge that are abnormal in intensity like strong attachment to unusual objects.
• There are marked hyper- or hyporeactivity to sensory input or unusual focus on sensory aspects of the environment, such as indifference to pain, adverse response to specific sounds or textures, excessive smelling or touching of objects, visual fascination with lights or movement.

Heterogeneity

• ASD is a heterogeneous disorder.
• The causes of autism are not known.
• Both effects and severity can range greatly between individuals.

Autism and the MMR Vaccine

• Wakefield falsely made a link between autism and the MMR vaccine.
• The link has been been debunked numerous times.
• Offit and Coffin (2003) explain why the link should be disregarded.
• That the initial false link persisted constitutes a great failure of scientific communication.

Related Theories

• Deficits in Theory of Mind (ToM) can cause autism.
• Poor executive function can cause autism.
• Weak central coherence can cause autism.
• An extreme male brain can cause autism.

The Sally Anne Task

• In the Sally Anne Task, 85% of typically developing children passed the task.
• 86% of individuals with Down syndrome passed the task.
• Only 20% of children with ASD passed.
• Some with Autism passed, so the Theory of Mind cannot account for everything.
• ASD participants passed in a verbally mediated way and in a very conscious fashion (Happé 1995).

Double Empathy

• Sheppard and others have proven that people without Autism have issues reading emotions in people with Autism.
• They also are more likely to find autistic people unlikeable.
• This is known as double empathy.

Executive Function

• This refers to high-order control processes.
• Planning, inhibition, cognitive flexibility, multitasking, working memory, and attention are all lower in people with Autism.

Weak Central Coherence Deficit

• This refers to a local and detail-focused processing style.
• Features are perceived at the expense of global configuration and meaning, giving ASD strengths and weaknesses.
• Poor performance is seen in tasks requiring recognition of global meaning or integration of stimuli.
• Good performance is seen when attention is focused on the details.

Extreme Male Brain

• Baron-Cohen noticed that Autism Spectrum Disorder is more common in males.
• Studies show that testosterone in the womb is higher in males with ASD.
• It has been attempted to identify the difference betwene male and female brains.
• Empathising is the drive to identify and respond to another's emotions.
• "Female brain" better shows empathising better than systemising.
• Systemising is the drive analyse a system/derive the underlying rules that govern a system.
• Systemising also refers to the drive to construct systems.
• "Male brain" better Systemises than empathises.
• Socialising in Autism patients is systemised.

Critiques of the "male brain" theory

• Females of course can have Autism Spectrum Disorder, but it goes undiagnosed a lot.
• Some believe that females are better at masking.
• Poor evidence exists for male/female differences in general population.
• The evidence for a correlation between testosterone and the male brain theory is unconvincing.
• 50-70% have deficit on TOM, and EF.
• This supports the "spiky profiles" theory.

Williams Syndrome

• Prevalence is approximately 1:20,000
• Some reports claim the prevalence as 1:7,500 (Stromme et al., 2002).
• A Sporadic genetic disorder is implicated that rarely runs in families.
• It is caused by the Deletion of approximately 25-28 genes on chromosome 7.
• The main gene affected or implied is the elastin gene.
• Feeding difficulties and failure to thrive as newborns is implicated.
• This can cause extreme heart and blood vessel abnormalities (SVAS).
• Hyperacusis (sensitive hearing) is another outcome.
• Physical symptoms include facial dysmorphology, and short stature.

Down Syndrome

• Prevalence is approximately 1:1,000 worldwide.
• Cases involve Genetic trisomy of Chromosome 21.
• Other genetic mutation types also occur, but these are rare.
• In about 90-95% of cases trisomy occurs.
• Sucking and feeding problems can result.
• Congenital heart defects are implicated.
• Hearing and vision deficits can occur.
• Facial dysmorphology and slow growth are physical symptons.

IQ in DS and WS

• Full scale IQ scores for WS are 40-90 (mean 55) (Bellugi et al., 2000).
• This indicates a Mild-moderate learning difficulty (Searcy et al., 2004).
• By adulthood IQ in affected persons is severely delayed (IQ=2).

IQ over Development

• IQ in WS remains fairly constant, but lots of individual differences emerge (Mervis et al 2012).
• Differences between domains of skill are relatively small in patients with DS.
• The skill gaps are magnified as children age and develop.
• Therefore the DS cognitive phenotype undergoes developmental changes.

Language

• WS patients have better language skills when compared to children with DS matched for IQ (Jarrold et al., 1998).
• Language falls above full scale IQ in Williams Syndrom and the opposite in apparent in Down Syndrome (Gunn & Crombie, 1996; Jarrold et al., 1998).
• In patients with Williams Syndrome, language is a relative strength (Bellugi et al., 1990; Karmiloff-Smith et al., 1995).

Visuospatial Tasks

• Williams Syndrome and Down Syndrome both can lead to struggles with visuospatial tasks, but in different ways (Bellugi et al (1990)).
• It can also affect the ability to apply block design tasks.
• It has implications for drawing and navigation.

Williams syndrome vs Williams syndrome

• People with Williams Syndrome are good at both drawing and complex creative writing tasks.

Social Behavior

• Individuals who face WS (Frigerio, 2006; Klein-Tasman and Mervis, 2011) and DS (Kasari, 1995) seem to have a pro-social compulsion.
• People with those conditions like to explore social interactions and think a lot about other people.
• This may put these individuals at higher risk with things like 'stranger danger'.

Theory of Mind and Faces

• Patients in both WS and DS struggle with Theory of Mind.
• Where individuals with Autism Spectrum Disorder struggle with faces, people with Down Syndrome and Williams Syndrome enjoy looking at faces.

Summary

• Intelligence is low in both WS and DS; there is more change in DS than WS.
• Language is relatively spared in WS compared with DS.
• Visuospatial skills are relatively spared in DS compared with WS.
• Genetic factors such as with WS and DS, can lead to uniform trends.
• Variation within disorders has a strong link to environment and support.