Lecture 9: Autism

Question 1

Name the symptoms and diagnostic criteria for ASD according to DSM-5.

Answer 1

• Persistent deficits in social communication and social interaction across multiple contexts
• Restricted, repetitive patterns of behavior, interests, or activities
• Symptoms must be present in the early developmental period
• Symptoms cause clinically significant impairment in social, occupational, or other important areas of current functioning

Question 2

Name examples of symptoms of ASD.

Answer 2

• Deficits in social-emotional reciprocity
• Deficits in non-verbal communicative behaviors
• Problems with developing and maintaining relationships
• Stereotyped or repetitive speech or behavior
• Adherence to routine (difficulties with adaptive functioning)
• Restricted interests
• Hyper- or hyporeactivity to sensory input

Question 3

What is the general prevalence and course of ASD?

Answer 3

The worldwide prevalence is about 1-1.5%, with boys being 4 times more often affected. In general, ASD persists into adulthood.

Question 4

How many patients with ASD also show sensory processing issues?

Answer 4

95% show sensory processing issues.

Question 5

Which comorbidities are common in ASD?

Answer 5

ADHD, intellectual disability and epilepsy (very high comorbidity; brain areas important in ASD and epilepsy show overlap).

Question 6

Name some issues with treating ASD.

Answer 6

There are hardly / no treatments for the core symptoms of ASD. Accordingly, only comorbid symptoms are treated. However, the treatments are not biologically informed.

Question 7

Name some cognitive dysfunctions seen in ASD.

Answer 7

Emotional, (selective) attention, adaptive functioning, inhibition and memory.

Question 8

How did ASD patients score on affective-face processing, go-no-go and set-shifting tasks?

Answer 8

ASD patients are significantly slower and make more errors in these tasks.

Question 9

Regarding genetics, how high is the heritability of ASD?

Answer 9

The heritability is about 80%.

Question 10

Name examples of neural pathology in ASD.

Answer 10

In ASD there is a significant cortical overgrowth between 2 and 4 years of age, a reduced area of the corpus callosum, under-connection in a widely distributed set of networks and changes in the neural activity during tasks involving social and affective judgments and differences in the processing of facial and non-facial stimuli.

Question 11

Name and describe a potential biological mechanism underlying ASD.

Answer 11

Imbalance between excitation and inhibition in the brain, in particular in circuits governing sensory processes, memory, and social and emotional behaviors.

Question 12

What are special aspects of ASD with comorbid epilepsy?

Answer 12

• strong aversive (hypersensitive) reactions to sensory stimuli
• altered EEGs/ brain rhythms
• dysfunction of GABAergic transmission
• i.e. hyperexcitability

Question 13

Which neurotransmitters are assumed to be involved in the development of ASD? What could be an underlying mechanism?

Answer 13

GABA and glutamate. In ASD there is either too few inhibitory GABA or too much excitatory glutamate leading to the excitation-inhibition disbalance seen in ASD.

Question 14

How could so-called minicolumns be related to the excitation-inhibition disbalance?

Answer 14

If minicolumns are densely packed there is a problem with migration leading to less or dysfunctional interneurons (inhibitory). Accordingly, GABA levels go down, inhibition goes down and excitation goes up (e.g. causing seizures).

Question 15

Which EEG waves are found to be abnormal in ASD?

Answer 15

Gamma (during face processing) and alpha waves (increased and earlier peak).

Question 16

Name some possible E/I treatment options.

Answer 16

GABA, glutamate, oxytocin, mTOR, bumetanide and TMS.

Question 17

Name the important brain areas for TMS treatment.

Answer 17

DLPFC, IFG, SMA, DMPFC and ACC.