Chapter 26: Autism spectrum disorders Flashcards
1
Q
What is Autism spectrum disorder (ASD)?
A
- Autism spectrum disorder (ASD) = a developmental disorder involving behavioral deficits in 2 distinct domains:
1. Persistent deficits in social communication and social interaction, and
- Restricted, repetitive patterns of behavior, interests and activities.
2
Q
Which levels of severity does the DSM-5 distinguish and what are these levels based on?
A
- DSM-5 distinguishes the levels of severity of ASD based on the degree of support at each level.
- The levels are:
- Level 1: requires support.
- Level 2: requires substantial support.
- Level 3: requires very substantial support.
3
Q
Why is making an ASD diagnosis more complex in adulthood than in childhood?
A
- ASD is adulthood almost always concerns a milder form within the autism spectrum, in which people have learned social behavior over the years as compensation and camouflage for the autistic symptoms.
- When a patient presents to the mental healthcare at adult age, there are often comorbid disorders or psychosocial problems, which can obscure the autistic symptomatology.
- A developmental history is no longer possible at an adult age.
- It can be difficult to distinguish between ASD, anxiety disorders and schizophrenia because there is a great overlap.
- There is also a phenomenological overlap with various personality disorders.
4
Q
What are common features that mark problems in social interaction, communication and behavior in ASD, despite the heterogeneity in the clinical picture?
A
- Avoiding eye contact (some people have to consciously learn to make eye contact, which can become ‘staring’).
- Monotone and little/no voice attuned to the situation.
- Little use of supportive gestures, rigid motor skills.
- Formal and pendant language.
- Difficulty with structure.
- Difficulty with communicating or little initiative in this.
- Highly value fixed routines/predictability.
- Sensory under- or over-sensitivity.
- Abnormal information processing (easily overstimulated).
5
Q
What are factors that play a role in that the prevalence of ASD has risen?
A
- ASD is recognized early than it used to.
- ASD is better diagnosed.
- The world is getting more demanding (e.g., of social skills).
6
Q
What do twin studies tell us about ASD?
A
- Twin studies have shown that ASD is approximately 90% genetically determined, making it one of the most heritable disorders within psychiatry.
7
Q
What have research into ASD subgroups shown about chromosomes associated with ASD?
A
- Chromosomes 2 and 7 are associated with language developmental problems.
- Chromosomes 1, 15 and 17 are thought to be associated with language rigidity and obsessive-compulsive behavior.
- A link between the X chromosome and ASD is also thought to exist, since ASD occurs 4x more often in men and women (women have another X chromosome to compensate the defect on the one X chromosome and men don’t).
8
Q
What has research shown about cerebrum/brain volume abnormalities in people with ASD?
A
- +/- 20% of children with ASD have macrocephaly.
- Macrocephaly = a head circumference 2 standard deviations larger than the population average.
- This is related to the size of the brain mass (particularly frontal and temporal lobes).
- Growth mainly occurs during first 2 years of life, but the growth process of the brain volume is slower in the 5th year of life.
- As a result of white matter disorders in adolescents and adults with ASD, there appears to be reduced integration and connectivity, particularly in frontostriatal and parieto-occipital networks.
- The increase in brain volume is in turn counterbalanced by a decrease in the volume of the corpus callosum.
9
Q
What has research shown about the limbic system and cerebellum in people with ASD?
A
- Research about the limbic system in people with ASD has found:
- A higher cell density with smaller cells was found in the hippocampus, the amygdala and the entorinal cortex in all age groups.
- The amygdala is less activated in people with ASD for recognizing faces and for tasks that call on the theory of mind (because of reduces emotional arousal to stimuli).
- On the other hand, the amygdala seems over-activated when people with ASD look someone in the eye (> has to do with social anxiety).
- No abnormalities were found in the activation of the fusiform face area (FFA).
- Research about the cerebellum in people with ASD has found:
- Fewer purkinje cells are found in the posterior inferior parts of the hemispheres, as well as deviations in growth development.
- The cerebellar abnormalities in ASD are usually related to motor clumsiness and attention problems.
- There are indications that the mirror neuron system does not function properly in people with ASD (particularly in social or emotional tasks).
10
Q
What has research about neurochemistry and endocrinology found in people with ASD?
A
- Neurochemical studies of ASD have not yet provided an unambiguous picture and there are no known effective pharamceutical interventions for the core symptoms of ASD.
- Medication for ASD is therefore focused on the psychiatric comorbidity.
- Increased serotonin levels in early development can lead to loss of serotonin receptors, resulting in disrupted neuronal development.
- Peripheral serotonin levels are elevated in +/- 1/3 of people with ASD.
- Testosterone also has received a great deal of attention.
- Oxytocin also has a possible therapeutic effect on the core social symptoms of ASD.
11
Q
What is the extreme male brain theory of autism?
A
- The extreme male brain theory of autism = posits the idea that ASD is an extreme form of male thinking.
12
Q
What is the theory of mind (ToM)?
A
- The theory of mind = the ability to put one’s thoughts, feelings and intentions into someone else’s place.
- This makes ToM an important condition for being able to move (understand and predict) in a social environment.
13
Q
What has research of the theory of mind shown about people with ASD?
A
- That people with ASD do not have a fundamental defect in ToM, but rather a delay in the development of ToM skills.
- Individuals with ASD continue to have problems with social interactions, although they’re often able to perform correctly on ToM tasks.
- It is also possible that people with ASD barely use ToM.
- The most common hypothesis is that ASD involves a deficit in spontaneous mentalizing.
14
Q
What does spontaneous mentalizing mean?
A
- Sponteneous mentalizing = spontaneously encoding socially relevant information and automatically processing the mental states of another.
15
Q
What does the central coherence hypothesis about ASD mean and involve?
A
- The central coherence hypothesis = people with ASD cannot automatically process information globally and in context in order to arrive at a meaningful, coherent interpretation of the environment, but they can process information fragmentally and at a local level.
- According to Frith, people with ASD have a weak central coherence.
- A clouding factor in this theory is that central coherence is always operationalized in a different way.
- Weak central coherence is composed of 2 factors:
1. Good analytical perception.
2. Weak meaning perception. - Other research found that central coherence is not so much a problem in recognizing global features or seeing meaning, but rather about preference (bias) for processing information at the local level.
- Central coherence is a feature that varies in the normal population and is therefore seen as a stylistic feature rather than a defect.
