Autistic Spectrum Disorder

Question 1

What are the 5 different disorders under the umbrella term ASD?

Answer 1

– Asperger’s Syndrome 
– Rett’s Syndrome
– Childhood Autism
– Pervasive Developmental Disorder
– Pervasive Developmental Disorder NOS

Commonality - difficulties in social interaction and social communication

Question 2

Triad of impairments in ASD

Answer 2

– impaired social interaction

• impaired communication
• restricted interests
• social imagination
• repetitive behaviours (later added)

Question 3

Social communication in ASD

Answer 3

• Generally good language skills but find it hard to grasp the underlying meaning of conversation
• Difficulties understanding jokes, idioms, metaphors and sarcasm
• Voices often sound monotonous (american accent)
• Language can be pedantic and idiosyncratic (grammar nazi)
• Narrow interests which dominate their conversations (lack of reciprocity)
• Difficulty sharing thoughts and feelings

Question 4

Social interaction in ASD

Answer 4

• Difficulties picking up non- verbal cues
• Appear self-focused and lacking in empathy, when in fact, they are simply trying to figure out social situations
• Continually struggle to make and sustain personal and social relationships

Question 5

Social imagination in ASD

Answer 5

• Difficulties thinking flexibly and in abstract ways
• Inability to understand other people’s points of view, taking things literally
• Difficulties applying knowledge and skills across settings with different people
• Difficulties projecting themselves into the future or planning goals sensibly

Question 6

Repetitive behaviours in ASD

Answer 6

• Stereotyped or repetitive motor movements, use of objects or speech
• Insistence on sameness, inflexible adherence to routines, or ritualised patterns of verbal or nonverbal behaviour
• Highly restricted, fixated interests that are abnormal in intensity of focus
• Hyper- or hypo- reactivity to sensory input or unusual interest in sensory aspects of the environment

Question 7

Epidemiology of ASD

Answer 7

Prevalence - 1% to 2%
5M:1W
Spectrum is widening (some clinicians have a higher threshold for diagnosis than others)

Question 8

Explain the gender differences in ASD (why M>W)

Answer 8

– Sex hormones play an important role in the organisation of brain circuits during early development
– Receptors for sex hormones are widely distributed in the brain and influence neural signalling
– Poor specificity in diagnostic tests for females
• Some evidence ( Cambridge Centre for Neuropsychiatric Research, 2014)
– Sex Hormone Binding Globulin (SHBG) levels are reduced in females with Asperger’s syndrome, pointing to higher levels of free testosterone
– Male-specific increases in the levels of several inflammatory markers

Question 9

Autism and gender identiry

Answer 9

GID is 3-4X more common amongst people meeting diagnostic criteria for ASD than general population

Young people with GID commonly have autistic traits

Studies in girls with congenital adrenal hyperplasia, (prenatally exposed to high levels of testosterone) showed more traits of ASD than controls and higher levels of Gender dysphoria

Question 10

List the causes of ASD

Answer 10

Environmental
Biological
Genetic

Miscellaneous:
– Rubella (German measles) in the pregnant mother
– Tuberous sclerosis
– Fragile X syndrome (the most common inherited form of intellectual disability)
– Encephalitis (brain inflammation) – Untreated phenylketonuria (PKU)

Question 11

Genetics as a cause of ASD

Answer 11

Strongly heritable

Chromosomal abnormalities involved - deletion, duplication, inversion

Question 12

Environmental factors as a cause of ASD

Answer 12

Teratogens - first 8 weeks from conception

heavy metal toxicity and exposure to particular diets (unreliable studies)

Question 13

Biological factors as a cause of ASD (mostly perinatal)

Answer 13

• Umbilical-cord complications
• Fetal distress
• Birth injury or trauma
• Multiple birth and maternal haemorrhage
• Low birth weight/small for gestational age
• Congenital malformation,
• Meconium aspiration
• Neonatal anaemia, ABO or Rh incompatibility, and hyperbilirubinaemia

Question 14

Neuroanatomy of Autism

Answer 14

Pathological areas - frontal lobe (social impairment), amygdala, cerebellum (balance and coordination)

Amygdala - associated with anxiety and social communication skills - 13-16% larger in autistic boys

Question 15

Neurochemistry of autism

Answer 15

• Glutamate receptors, GABA, Serotonin seem implicated
• GABA - regulation of early developmental stages of cell migration, neuronal differentiation and stages of maturation
• Glutamate - excitatory neurotransmitter which dysregulation can lead to neuronal damage
• Serotonin - regulation of crucial steps of neuronal development
• Role of catecholamines and acetylcholine is poorly understood