Week 12/1 Autism Pdd Ii Flashcards
Current vaccination schedule in Quebec
14 separate shots by 6 years of age
Includes pneumonia, flu, rotavirus, chickenpox
Causes of autism?
Environmental Factors
Toxin hypotheses
– Gluten-based diet (cereal)
– Casein-based diet (milk)
– Toxic substances during pregnancy
Vaccinations
Increase in number of vaccinations children receive 1900 – 1 – Small pox
Thimerosal in vaccines issue?
Preservative in vaccines
Removed from nearly all vaccines in 2001 (e.g., some flu vaccines, not given to children)
Mercury
Symptoms of autism are noticed right around the time
children get their vaccinations
Reasonable biological explanation
Wakefield et al. 1998
12 children
Normal development followed by onset of behavioral difficulties and gastrointestinal problems
For 8 children, onset was linked to MMR vaccine by parents or physician
Note that the authors were careful to point out that this study did not prove a link between behavioral problems and vaccination
Also noted that only a subset of autistic cases linked to vaccine!
After publication, MMR vaccine rates dropped
In UK
1996 – 92%
2006 – 85% (compared to 94% for other vaccines)
2006 incidence rates for measles and mumps were 13 and 37x times higher than in 1997, so paper had consequences!
No scientific evidence linking vaccines to autism!
No scientific evidence linking vaccines to autism!
Subsequent research evidence
12 epidemiological studies have found no link between the MMR (measles/mumps/rubella) vaccine and autism
Largest: All children born in Denmark between January 1991 and December 1998 (N = 537, 303)
6 studies have found no evidence of a link between thimerosal and autism
3 studies have found no evidence that thimerosal is associated with more minor neurological difficulties
Most recently
De Stefano et al. 2013, Journal of Pediatrics
Examined association between level of immunological stimulation in first two years of life and development of autism
Found no association
Greater number of vaccines not associated with autism
Scientific inference
Null hypothesis: Assume no relationship
Using probability theory, determine how likely the observed relationship is if there is really no relationship
Could we expect to observe this association by chance?
We cannot quantify the likelihood of no relationship
We cannot “prove” the null hypothesis
U satisfying to parents/ppl
Issue is herd mentality of vaccine not working.
More cases, some ppl cannot take vaccines
Update on Landet paper
Lancet retracted the paper
In January 2011, reported in the British Medical Journal that the data reported were in fact fraudulent
Genetic causes of autism
Heritability
– Identical twin concordance of 60-90%
– Have one child with ASD, 1/15 of second births will have ASD
– Overall, evidence that autism is over 80% heritable
– Likely involves gene x gene interactions (5-100!)
Brain Development in asd
Evidence of abnormalities, but not clear if causal
Differences in structure
– Many areas (frontal lobe, cerebellum, medial temporal, limbic)
Differences in function
– Very high rates of epilepsy and seizures
– Decreased activation of emotion processing regions
– Structural and functional differences in the amygdala
– Decreased activation of “mirror neurons”
– Altered activation of facial recognition areas
– Children as young as 6 months show different brain activity when they see their mother versus a stranger
– Children with autism don’t show this
“Biomedical” Treatments
For ASD
Vitamins and diet
Vitament supplements
E.g., C, B6,magnesium
Diet
Gluten-free Secretin (for ulcers)
Otherwise – Few studies, methodologically problematic
No strong evidence
Secretin for ASD
Used to treat peptic ulcers
Three children with autism received it for unrelated conditions and improvement in symptoms of autism noted
Several well-designed studies showing no effect
Meta-analysis of 7 large studies concludes secretin is not effective
3 behavioural models to treat asd
Language and ommunciation foci
Social skills foci, eg. imitate others, demonstrate affection, reciprocate/initiale tantrum,
Tantrums, stim focIt
ABA
FLOORTIME
TEACH
Psychosocial Treatments for ASD
Common models Behavioral (ABA)
DIR / floor time
TEACCH
Common features
Early intervention
Many hours
Many staff
Structured
Intense family involvement!
ABA
Discrete Trial Training, kid q’s
Structured behavioral approach
Therapist begins with a prompt that should elicit the desired skill/behavior (show me the 2! Show me the pretzel!)
Prompt the behavior
Reinforce the desired behavior
Shaping, baby steps
Incidental training
Reinforcing naturally occurring behaviors
UCLA Early Autism Project
Participants
Preschoolers with autism (mean age 32 months) Varying levels of MR and impairment
Design
Non-random assignment to conditions Ethical concerns
Parent protest
Children assigned to treatment condition unless there was an insufficient number of staff members (in which case assigned to control)
Children assigned to two groups
19 children assigned to ABA therapy (40 hrs / week)
19 children assigned to Special education + less intense ABA (10 hrs /week)
Therapy lasted for at least two years
Third group was added for analysis – children who had attended special education but not received any individual therapy
Guard against referral bias,
No difference between treatment and control groups
on 19 out of 20 variables (e.g., age at diagnosis,
abnormal speech, self-stimulatory behavior)
Control group 1 was slightly older but this was shown not to be related to outcomes
In general, appears that the groups were comparable at intake
Outcomes (age 7)
47% of youths in intense ABA “recovered”
Completed first grade without support Promoted to second grade
IQ scores increased
2% of youths in control conditions (only one child)
Outcomes (Age 13)
Follow up of the 9 children with the best outcomes
showed that they maintained their gains
42% of children in intervention group were identified as having mild ID and placed in special ed classes
11% classified as having profound ID
Gains were maintained
