Download Is autism increasing?

Autism
Reasons for study
• Many people affected and serious disability
• Genetics and gender
• Parsing of human personality and mind – a window into mental machinery
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Brain injury
Brains scans
Drugs
Disorders
Developmental
Evolutionary theories
What is autism
• Appears early – by age 3
• A syndrome
– Collection of symptoms – not all or always in same person
• Complicates diagnosis
• And etiology
– Can vary in severity – a spectrum disorder
The main symptoms
• Social impairment
• Verbal and nonverbal communication impairment
• Restricted and stereotypic behavior patterns
Social impairment
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Nonverbal behaviors
Cannot establish friendships
No spontaneous sharing
Lack of social reciprocity
Lack of empathy
Social impairment – nonverbal behavior
• Blunt or flat affect
• Too much affect – silly laughing
• Lack of relevant pointing or visual gaze
Social impairment – friendships
• Hard to establish
• Don’t understand purpose or meaning
• May want friends but no idea how to establish friendship
• Alternatively may believe everyone is a friend
Temple Grandin, Thinking in Pictures
• “Social interactions that come naturally to most people can be
daunting for people with autism. As a child, I was like an animal that
had no instincts to guide me; I just had to learn by trial and error. I was
always observing, trying to work out the best way to behave, but I
never fit in. When other students swooned over the Beetles, I called
their reaction an ISP – interesting sociological phenomenon. I was a
scientist trying to figure out the ways of the natives. I wanted to
participate but I didn’t know how”
Temple Grandin
• “Although business relationships can be easily learned by rote, dating
is difficult. The social skills ones needs to rent an apartment and keep
a job were easier for me to learn than the skills for dating because I
have very few emotional cues to guide me through complex social
interactions.”
• “I can act social, but it is like being in a play”
• Goes on to say that having relationships on the phone are easier
because there are fewer social cues to code and deal with.
Social impairment – no spontaneous sharing
• Ability to show objects of interest to others is a
developmental milestone
• But not achieved by the autistic
• Child on a walk sees a favorite dog but not point this out to
mother
Social impairment – no social reciprocity
• May monopolize conversation
• Or walk away from enjoyable conversation
• No understanding of give and take
Social impairment – lack of empathy
• Cannot take the point of view of others
• Fails to understand emotions of others
Communication I
• Delay of language developmental
– Sometimes regression
– Many do not really speak
• Cannot maintain a conversation
– Cannot find topic of mutual interest
– Insist that conversation be about own interest
– May begin by asking some detail – other’s birth date
Communication II
• Stereotyped use of language
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Requiring others to say same things
Echolalia – repeating words
Switching pronouns – say “you” for “I”
Metaphorical language
• “Give me a hand, Jack”
• For “I need help”
Stereotyped behaviors
• Deep concentration
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Perceptual
Thought
Conversation
Persistent occupation with details of objects
• Ritualistic behavior
• Stereotyped body movements – rocking
Auxiliary symptoms
• Uneven cognitive patterns
– Usually much better on spatial or math tasks
– Some savants
• Often profound retardation
• Hyperactivity and tantrums
• Unusual responses to pain
– Under or over responsive
– Often don’t want to be held or cuddled
Quotes from Grandin
• “I think in pictures. Words are like a second language to me. I
translate both spoken and written words into full-color
movies, complete with sound, which run like a VCR tape in
my head.”
More quotes
• “The Lord’s Prayer was incomprehensible until I broke it down into
specific visual images. The power and the glory were represented by
a semicircular rainbow and an electrical tower. The words, ‘Thy will be
done’ had no meaning when I was a child, and today the meaning is
still vague. Will is a hard concept to visualize. When I think about it I
imagine God throwing a lightening bolt”
Prevalence
• Estimated rates vary but between 10 and 20 per 10,000 -may .1-.2%
• About 10 times more common in boys but more severe in
females
• Early studies found that it was more common is higher SES
families but this is almost certainly entirely due to better
recognition among better educated.
Is autism increasing?
• Better detection
• Perhaps because some children are now born and viable that were
not a generation or two ago – fetal salvage
• To the extent it is genetic may be a disorder that tends to get worse
over generations
– Children of mildly eccentric people may show the disorder more strongly
– Technology haven for people with mild forms
Clearly a genetic disorder
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Concordance rates among MZ twins is about 60%
About 5% for DZ
Over 100 times more likely in sibs
No single gene
– HOX genes on chromosome 7 – control early fetal development
– X chromosome
• Girls with single X (Turner’s syndrome) are almost as likely as boys to be autistic
– Recent evidence suggests separate genes for social and obsessive features
Other biological factors
• Brain areas
– Amygdala – smaller and more densely packed neurons
• In animals removal of amygdala produces autistic like symptoms
– Hippocampus
• Memory
• Removal produces stereotypic behaviors
– Attention areas
Other factors
• No evidence of parental or home environment
• Environmental pollutants
• Mothers who smoke
• Yeast infections in stomach
• Mercury in vaccine.
Causes
• All correlational research
• Clearly genes causes
– But not completely
– Must be other factors
– Still need a causal history
• Mediate causes in terms of psychological disorders
• Distal causes in terms of biological factors
• Need a theory
What do we expect from a theory?
• A causal network
• Isolating key symptoms from more corollary ones
– How autistic people differ from non-autistic
– What symptoms tell us about normal functioning
• Cures or remediation
Theories
• Unfeeling and cold mothers – Bettleheim
• Symptoms
Memory problems
• Often show enhanced recency effects but decreased primacy
effects in serial recall
– Suggesting a reliance on acoustical memory
– Relative failures in encoding
• Have trouble with categorization and do not show category effects
• Often have quite good rote memory, but the information is repeated without any change
in meaning or evidence that it has been interpreted in any way
Concrete thinking – Temple Grandin
• “Unlike those of most people, my thoughts from video-like, specific
images to generalizations and concepts. For example, my concept of
dogs in inextricably linked to every dog I’ve ever known. It’s as if I
have a card catalogue of dogs I have seen, complete with pictures,
which continually grows as I add more examples to my video library”
• “Pulling up facts quickly is sometimes difficult, because I have to play
bits of different videos until I find the right tape.”
Attention
• An early theory suggested that autistic people have trouble filtering
out extraneous information
– Hence they are flooded with stimuli
– And focus on a limited range of stimuli to help shut out the extraneous
• That theory is probably not correct but clear such people do have
trouble switching attention from one modality to another and from
one stimulus to another.
Attention quotes
• Grandin, “When two people are talking at once, it is difficult for me to
screen out one voice and listen to the other”
• A young man “described difficulty hearing and seeing at the same
time as his sensory channels got mixed up. Sound came through as
color while touching his face produced a sound like sensation”
• Donna Williams describes herself as a mono channel; when she is
listening to someone speak, visual input loses its meaning. She is
unable to perceive a cat jumping on her lap while she is listening to a
friend speak”
Emotional problems
• Most autistic people have little or no emotional feeling. They often
describe themselves like Spock on Startrek
• Emotions are not disruptive of our thought as many people tend to
assume but central to it. They guide our thought, help us negotiate
relationships, and perhaps even help us organize our thoughts.
Theory of mind theory
Baron-Cohen’s gender based theory
• Women’s brains are built for empathy and communication
• Men’s brains are built for problem solving
– Focus on structure
– Especially on details
– Things rather than people
• Keeping in mind great overlap between sexes on both features
Autistic people have hyper-male brains
• Attention captured by detail
• Lack of empathy and understanding of others
• Accounts for two basic facts
– Autism is far more common (10 x) among males than females
– It’s a spectrum disorder
Treatment options
• Working on behavior
• Facilitated communication